Game Maker Helpavailable to control all aspects of your game. The following topics exist in this section: Language overview Computing things Game play User interaction Game graphics

DesigningGameswith

GameMakerVersion8.0

WrittenbyMarkOvermars

ThedocumentationforGameMakerisdividedintofourparts:

UsingGameMaker

ThissectiondescribesthebasicuseofGameMaker.Itexplainstheglobalideabehindtheprogramanddescribeshowtoaddsprites,backgroundandsoundsandhowtodefineobjectswitheventsandactionsandhowtoaddthemtorooms.

Thefollowingtopicsexistinthissection:

IntroductionInstallationUpgradingtotheProEditionGettingStartedTheGlobalUserInterfaceDefiningSpritesSoundsandMusicBackgroundsDefiningObjectsEventsActions

CreatingRoomsDistributingyourGame

Advanceduse

ThissectiondescribesthemoreadvancedaspectsofGameMaker.Itdealswithpaths,fonts,timelines,scripts,andtechniquesforcreatingtiledroomsandusingviewsinrooms.


AdvancedUserInterfaceMoreaboutSpritesMoreaboutSoundsandMusicMoreaboutBackgroundsMoreaboutObjectsMoreActionsConstantsTriggerEventsIncludingFilesMoreaboutRoomsFontsPathsTimeLinesScriptsExtensionPackagesExportingandImportingResources

Polishingyourgame

Thissectiondealswithhowtoturnyourprojectintoafinishedgame.Itdescribeshowtoaddhelpinformationtoyourgame,howtosetthevariousoptionsforyourgameandhowtocreatestand-alonegamesthatyoucandistributetoothersandcanberunwithouttheneedforGameMaker.


GameInformationGlobalGameSettingsSpeedConsiderations

TheGameMakerLanguage

GameMakercontainsabuilt-inprogramminglanguage.Thisprogramminglanguagegivesyoumuchmoreflexibilityandcontrolthanthestandardactions.ThislanguagewewillrefertoasGML(theGameMakerLanguage).InthissectionwedescribethelanguageGMLandwegiveanoverviewofallthe(closeto1000)functionsandvariablesavailabletocontrolallaspectsofyourgame.


LanguageoverviewComputingthingsGameplayUserinteractionGamegraphicsSoundandmusicSplashscreens,highscoresandotherpop-upsResourcesChangingresourcesFiles,registry,andexecutingprogramsDatastructuresCreatingparticlesMultiplayergamesUsingDLL's3DGraphics

WhatisNew

Version8.0ofGameMakerhasalargenumberofimprovementsoverversion7.0.Belowthemostimportantchangesaredescribed.

Incompatibilities

Textsplashscreenscannolongershowimages.However,websplashscreenshavebeenaddedthatcanshowfullhtmldocumentswithimages,etc.

Anumberofchangeshavebeenmadetothefunctionsrelatedtospriteandbackgroundresources.ThisisduetothefactthatGameMakerusesacompletelynewmechanismfortheseresources.Ifyourgameusesalotofcallstofunctionsthatloadorsaveimageresourcesontheflyyouarestronglyrecommendedtokeepusingtheoldversion7.0forthatgame.

Ifyouuseextensionpackagesyouwillhavetoreinstallthem.

Somechangeshavebeenmadetothetimelinemechanismthatcanleadtoincompatibilities.Inparticular,assigningatimelineandstartingitarenowtwoseparatethings.

Animportantbughasbeensolvedinwhichcollisioneventswhereexecutedtwiceiftwoobjectshavecollisioneventswitheachother.Somegameshowevermighthavereliedonthisbugand,hence,mightnolongerfunctioncorrectly.

News

GameMakernowdefaultshowsaNewspagewhenitisstarted.Herenewversionswillbeannounced,newresourceswillbeindicated,thereisinformationaboutcompetition,andgamedesigntipsandtricks.Newsis

shownonlyonceaday.IntheProEditionthiscanbeswitchedoff.YoucanalwaysaccessthenewsthroughtheHelpmenuandyouareencouragedtoregularlycheckthenewsforimportantinformationaboutGameMaker.

Tutorial

GameMakernowhasastandardbuilt-intutorialforbeginners.Itisshowninapanelattherightofthescreen.Experienceduserscanindicatethattheydonotwanttoseethetutorialanymore.Toaccommodateforthetutorialpanel,GameMakerisnowdefaultstartedinfullscreenmode.Itdoeshoweverrememberitssettingssochangingitoncetowindowedmodewillfromthatmomentonstartitinthatmode.

Alpha-blendedbackgroundsandsprites

ThenewversionGameMakerusesbackgroundsandspriteswithalpha(transparency)channels.Thismakesitpossibletocreateandusemuchnicersprites.PNGfileswithsuchinformationarenowcorrectlyloaded.Thespriteandimageeditorhavebeencompletelyrewritten,includingmanynewdrawingoptionsandeffects.Anewspritefileselectorwasaddedthatshowstheanimationsinthesprites.Alsowebundlealargenumberofhigh-qualityspriteswithGameMakerthatyoucanuseforfreeinyourgames.

Enhancedcollisionchecking

Younowhavemorecollisioncheckingoptions.Forexample,youcanindicatethatcollisionsshouldbewithanencloseddiskandyouhavebettercontrolovertheboundingbox.Thesub-imageofthespritecanhaveacombinedmaskandyoucansetthedependenceonthealphatransparencyvalue.

Splashscreens

Anewfunctionsplash_show_web(url,delay)hasbeenaddedthatcanbeusedtoshowwebpagesassplashscreens.Youcanalsouselocalhtmlpagesforthis.Thisallowsforapowerfulmechanismtoe.g.createhelppages.Aclosebuttonisaddedtothesplashscreens.Alsoanumberofnewactionshavebeenaddedtoshowthedifferenttypesofsplashpagesandtochangesplashsettings.(TheoldShowVideoandWebpageactionshavebeenremovesasthenewactionsincludethem.Theywillthoughstillworkinoldgames.)

Triggerevents

Anewtypeofeventhasbeenintroduced:Triggerevents.Triggereventsyoucanspecifyyourself.Yougivethemanameandacondition,writteninGML.Afterthistheycanbeusedinallobjects,justlikeotherevents.WiththisyoucaneasilyextendthefunctionalityofGameMaker.

Timelines

Thetimelineshavebeenextended.Thepropertyformhasadditionalbuttonstoe.g.spreadoutthemomentsandtodeleteorduplicaterangesofmoments.Timelinescannowbepausedandrestartedandtheycanevenbeplayedbackwards.Alsotheycannowloopautomatically.

Importingandexportingresources

Thepossibilitytomergegameshasbeenreplacedbyamuchmoreextensivesystemtoimportandexportresources.Theusercanindicatewhichresourcestoexporttoafile(.gmres).Nexttheycanbeimportedinadifferentgame.Inprincipleonlyoneresourcecanexistforeachname.Whenthereisanameconflictwhenimportingtheusecanspecifytokeeptheoriginal,replaceanyway,taketheonethatismostrecently

changed,orkeepboth(notrecommended).Tobeabletodothethirdoption,allresourcesnowkeeptrackofwhentheywerelastchanged.

Rewrittenscriptandcodeeditor

Thebuilt-inscript/codeeditorhasbeencompletelyrewritten,makingitaloteasiertowritecode.Forexamplethereispop-upfunctionnamecompletion,argumenthelp,matchingbrackets,improvedcolorcoding,linenumbers,on-the-flyerrorchecking,codesnippets,andasophisticatedfindandreplacefunctionality.

Speedimprovements

Thespeedofgamesthatusecodehasbeenconsiderablyimproved.Aspeed-upofupto100%issometimespossible.Alsotheloadingtimeforgamesisoftenconsiderablyimproved.Alsowhenrunningastand-alonegame.

Otherchanges

Thereareanumberofotherchangesandadditions.Herearesomeoftheimportantones.

Youcannowusehighqualityiconsforyourgames.Constantscannowbedefinedintheirownform(ratherthanthroughtheGlobalGameSettings).Asaresulttheycanremainvisiblewhileyouaree.g.writingscripts.Youcanalsoloadandsavetheconstantstotextfiles.AlsoincludedfilesarenolongershownintheGlobalGameSettingsbutintheirownform.ManysmallvisualimprovementsAddedfunctionrandom_range(x1,x2),irandom(x),andirandom_range(x1,x2).Thelatterdogiveintegerresultsandcanincludexorx2.

Addedfunctionsmouse_wheel_upandmouse_wheel_down.Addedafunctionset_application_title(title)tosetthetitleoftheapplication(whichisshowninthetaskbar).Addedfunctionfile_text_eoln().Addedread-onlyvariabedebug_mode.Thereisnowagamesettingtodisallowscreensaversorpowersavingoptions(sleep,hybernate)whilethegameisrunning(defaultdisallowed).Addedfunctionsdisk_size(drive)anddisk_free(drive)andavariablegamemaker_version.RuntimeerrormessagesbetterindicatethepositionoftheerrorYoucannowchangetolocationofthetemporaryfiles,seethepageonPreferences....

Correctedbugs

Thefollowingbugswerecorrected.Anumberofothersmallerbugswerecorrectedaswell.

AnerrormessagewhenstartingtheMakeronVistawithActiveUserControlisnowremoved.CorrectedabugthatwhenusingAltmanyfieldsinformsbecameinvisibleunderVista.Correctedabugwithactionhintsnotshowingintheobjectandtimelineforms.Whenopeningagameorstartinganewone,nolongerforallopenchangedresourcewindowsaseparatesaveconfirmationquestionisasked.Correcteda(sortof)errorwiththeprecisionofcomparisonoperatorsincode.SolvedbugwithabadbackgroundfortheAppliesTofieldincodeeditor.Creatingastandalonenowcorrectlycheckswhetherthereareanyrooms.ReplacedallCtrl+AltcombinatationsbyShift+Ctrlbecausesomeof

combinationsareimportantforGermankeyboards.Alsocorrectedtheshortcutforcreatingsprites.Insimplemodes,short-cutsforhiddenresourcesandmenuitemsnowaredisabledaswell.AlsotheScriptsmenuishidden.Correctedabuginthefunctionwindow_get_color().Increasedthelimitonthenumberofverticesindrawing3Dprimitivesformodelsfrom1000to32000.Correctedabuginignoringz-valueformodelvertices.CorrectedtheOutsideViewandBoundaryViewevents.Gamewillnowrun(withwarning)whenthereisnoenabledsoundcard.Whenthegamewindowloosesfocus,ioeventslikekeypressesarenowcleared.Correctedandimprovederrorreportingforthecreationcodeofroomsandinstancesinrooms.room_tile_addandroom_tile_add_extnowcorrectlysettheblendingcolortowhiteandreturnthecorrecttileindex.Nowcorrectlysettingtheapplicationtitletothefilename.Correctedabugindraw_line_width_colorwhenthelengthis0.Tileswithnegativescalefactorsarenowcorrectlydrawn.Changedthereadingandwritingofrealsintextfiles.Asdecimalseparatornowalwaysadotisused.However,whenreading,bothadotorcommaareaccepted.Agroupofresourcesthatisemptywillnowhavethecorrectclosedfoldericon.Solvedtheproblemwiththeflashingoftheresourcetree.Functionsstringandstring_formatnolongercrashwhenthenumberistoolargeandtheywillreturnthestringERROR.Longpathsarenowcorrectlydrawnwithdraw_path.Collapsingtheresourcetreenowworkscorrectly.Inanifcondition,avalueof0.5isnowtreatedastrue.Solvedabugthatsometimesoccuredwhenpressingthe~key.sign()functionnowcorrectlyreturns0whentheargumentis0.Inthepatheditor,whenchoosingaroom,clickingoutsidethemenunolongerclearstheroom.Slightlyenlargedthedebugformtoshowalltoolbaricons.Alsomadethewatchgridcolumnsscalewhentheformresizes.

Correctedabugthatcancauseacrashwhenresizingthegamewindowto0height.Solvedabuginds_grid_add/multiply/set_grid_region.Callstoscriptsandextensionfunctionsnowreturnavalueof0whentheydonotassignareturnvaluethemselves.Solvedaseriousbuginwhichcollisioneventswhereexecutedtwiceiftwoobjectshavecollisioneventswitheachother.Solvedabugindraw_text_extwithemptylines(multiple#)andaproblemwithdrawingstringsthatcontainsCR-LFpairs(whenusingmultilinestringsincode).Read-onlyfilescannowbeusedasincludedfileswithouterrors....

UsingGameMaker

GameMakerisaneasytouseprogramforcreatingyourowncomputergames.Thissectionofthehelpfilegivesyoualltheinformationyouneedforcreatingyourfirstgames.Latersectionswilldiscussmoreadvancedtopics,howtopolishanddistributeyourgame,andthebuilt-inprogramminglanguageGMLthatconsiderablyextendsthepossibilities.

InformationonthebasicuseofGameMakercanbefoundinthefollowingpages:

IntroductionInstallationUpgradingtotheProEditionGettingStartedTheGlobalUserInterfaceDefiningSpritesSoundsandMusicBackgroundsDefiningObjectsEventsActionsCreatingRoomsDistributingyourGame

Soyouwanttocreateyourowncomputergames

Playingcomputergamesisfun.Butitisactuallymorefuntodesignyourowncomputergamesandletotherpeopleplaythem.Inthepast,creatingcomputergameswasnoteasy.Commercialcomputergamesyoubuynowadaystypicallytakeoneortwoyearsofdevelopmentwithteamsofanywherebetween10and50people.Budgetseasilyreachmillionsofdollars.Andallthesepeoplearehighlyexperienced:programmers,artdesigners,soundtechnicians,etc.

ButGameMakerhaschangedthis.WithGameMakeryoucancreateyourowncomputergamesquicklywithouttheneedtolearnaprogramminglanguage.OfcourseyoushouldnotexpecttocreateyourownHalo4orVirtuaTenniswithinafewweeks.Butthatisalsonotnecessary.Thejoyofplayingagameisnotrelatedtoitscomplexity.Simplergames,likeTetris,Bejeweled,SpaceInvaders,etc.arealotoffuntoplayandaloteasiertocreate.

GameMakeroffersanintuitiveandeasytousedrag-and-dropinterfacethatallowsyoutocreateyourowngamesveryquickly.Youcanimportandcreateimages,sprites(animatedimages)andsoundsandusethem.GameMakerisbundledwithaconsiderablecollectionofsuchresourcestogetyoustarted.Youcaneasilydefinetheobjectsinyourgameandindicatetheirbehavior,andyoucandefineappealingrooms(levels)inwhichthegametakesplace.Andifyouwantfullcontrolthereisactuallyaneasy-to-useprogramminglanguagebuiltintoGameMakerthatgivesyoufullcontroloverwhatishappeninginyourgame.

GameMakerfocusesontwo-dimensionalgames.Soitisnotmeanttocreate3DworldslikeQuake,eventhoughthereissomelimitedfunctionalityfor3Dgraphics.Butdon’tletthisputyoudown.Manygreatgamesusetwo-dimensionalspritetechnology,eventhoughtheylookvery3-dimensional.Anddesigningtwo-dimensionalgamesisaloteasier

andfaster.

GameMakercomesintwoeditions,theLiteEditionandtheProEdition.TheLiteEditioncanbeusedfreeofchargebutitislimitedinitsfunctionalityandwilldisplaypopupmessages.Youcanthoughfreelydistributethegamesyoucreatewithit;youcanevensellthemifyoulike.Seetheenclosedlicenseagreementformoredetails.YouarestronglyencouragedtoupgradeyourcopyofGameMakertotheProEdition.ItwillconsiderablyextendthefunctionalityofGameMakeranditwillremovethelogowhenrunninggames.ThiswillalsosupportthefurtherdevelopmentofGameMaker.FormoreinformationonupgradingseetheProEditionpage.

ThishelpfilewilltellyouthemostimportantthingsyouneedtoknowaboutGameMakerandhowyoucancreateyourowngameswithit.Pleaserealizethat,evenwithaprogramlikeGameMaker,designingcomputergamesisnotcompletelyeffortless.Therearetoomanyaspectsthatareimportant:gameplay,graphics,sounds,userinteraction,etc.Startwitheasyexamplesandyouwillrealizethatcreatinggamesisgreatfun.Alsocheckthewebsite

http://www.yoyogames.com/

forlotsofexamples,tutorials,ideas,andlinkstoothersitesandforums.Andsoonyouwillbecomeamastergamemakeryourself.Enjoy.


Installation

Youprobablyalreadydidthisbutifnot,hereishowtoinstallGameMaker.Simplyruntheprogramgmaker80.exe.Followtheon-screeninstructions.Youcaninstalltheprogramanywhereyoulikebutitisbesttofollowthedefaultsuggestionsgiven.Onceinstallationiscompleted,intheStartmenuyouwillfindanewprogramgroupwhereyoucanstartGameMakerandreadthehelpfile.

GameMakeralsoinstallsaconsiderablenumberofimages,sprites(animatedimages)andsoundeffectsonyourcomputer,whichcanbeusedfreeofchargeinyourgames.Alsosomeexamplegamesareinstalled.AllthesecanbefoundinfolderswithinthelocationwhereyouinstalledGameMaker.

ThefirsttimeyourunGameMakeryouareaskedwhetheryouwanttoruntheprograminSimpleorAdvancedmode.Ifyouhavenotusedagamecreationprogrambeforeandyouarenotanexperiencedprogrammer,youhadbetterusesimplemode(soselectNo).Insimplemodefeweroptionsareshown.YoucaneasilyswitchtoadvancedmodelaterusingtheappropriateitemintheFilemenu.

Youwillalsobeshownatutorialattherightofthewindow.Thetutorialwillteachyouhowtoquicklycreateyourfirstgame.ItwillguideyouthroughthebasicstepsinusingGameMaker.IfyouhavenotusedGameMakerbeforeyouarestronglyadvisedtoworkyourwaythroughthetutorial.YoucanalwaystrythetutoriallaterthroughtheHelpmenu.

Requirements

AnycomputerthatislessthanfiveyearsoldshouldbeabletorunGameMakerwithoutanyproblems.

Tobemoreprecise,GameMakerrequiresaresonablymodernPCrunningWindows2000,XP,Vista,7,orlater.ADirectX8(orlater)

compatiblegraphicscardwithatleast32MBofmemoryisrequiredformostcreatedgames.Itrequiresascreenresolutionofatleast800x600and65000(16-bit)colors(preferablyfullcolor).AlsoaDirectX8compatiblesoundcardisrequired.Makesureyouhavethemostrecentdriversinstalled.GameMakerrequiresDirectXversion8.0orlatertobeinstalledonyourcomputer.(YoucandownloadthenewestversionofDirectXfromtheMicrosoftwebsiteat:http://www.microsoft.com/windows/directx/.)Whendesigningandtestinggames,thememoryrequirementsareprettyhigh(atleast128MBandpreferablymore,alsodependingontheoperatingsystem).Whenjustrunninggames,thememoryrequirementsarelesssevereanddependalotonthetypeofgame.

http://www.microsoft.com/windows/directx/

UpgradingtotheProEdition

GameMakercomesintwoeditions,theLiteEditionandtheProEdition.

TheLiteEditionismeantforthosethattaketheirfirststepsonthepathofdevelopinggames.Itcanbeusedforfreebutislimitedinitsfunctionality.Alsoitshowsapopuplogowhenrunninggamesandwillregularlyremindyouofupgradingtheprogram.WhenyouareusingGameMakerregularlyyouarestronglyrecommendedtoupgradeittotheProEdition.

TheProEditioncontainsconsiderablymorefunctionalityanddoesnotdisplayanylogosorpopupmessages.Moreprecisely,theProEditionhasthefollowingadditionalfunctionality:

NoGameMakerlogoisshownwhenrunningagame.Noregularpopupsremindyouofupgrading.Youcanuserotated,colorblendedandtranslucentsprites.Thereareadditionaloptionsinthespriteandimageeditors.Thereareadditionalactionsfore.g.CDmusic,rotatedtext,andcolorizedshapes.Youcanusespecialsoundeffectsandpositionalsound.Youcancreatesplashscreenswithmovies,images,webpages,texts,etc.Thereisaparticlesystemtocreateexplosions,fireworks,flames,rain,andothereffects.Anumberofadvanceddrawingfunctionsareavailable,forexamplecolorizedtextandtexturedpolygons.Itispossibletocreate3Dgamesusingfunctionsfor3Dgraphics.Itispossibletocreatemultiplayergamesthatcanbeplayedoveranetwork.Youcandefineyourownroomtransitions.Youcanusefunctionstocreate,load,andmodifyresources(sprites,backgrounds,etc.)whilethegameisrunning.Thereisacollectionoffunctionstocreateandusedatastructures.

Therearefunctionsformotionplanning.Yougetthepossibilitytoincludeadditionalfilesinthegameexecutablesthatcanbeusedwhenthegameisrun.TheProEditioncaneasilybeextendedusingextensionpackage.Thesecanbemadebyeverybodyandwillingeneralbeprovidedfreeofcharge.Threesuchextensionpackagesareincludedaddingmanyroomtransitions,windowsdialogs,andprintingfacilities.Youcandefineyourowntriggerevents.Youcanexportandimportresources,whichmakesiteasiertocollaborateongames.

UpgradingtheLiteEditiontotheProEditioncostsonly20EuroorUS$25(subjecttochange).Thisisaone-timefeethatwillatleastbevalidforallversions8.xofGameMaker.

WhenyouarerunningtheLiteEdition,wheneveryoustartGameMakerthefollowingformwillbeshown:

YoucanusethisformtoupgradetotheProEdition.Thereareanumberofwaystodothis.

Theeasiestwayistopurchasetheupgradeonline.TothisendpressthebuttonPurchaseProEditionOnline.YouwillbebroughttoawebpagewhereyoucanmakeyoupaymenteitherbycreditcardorthroughPayPal.ThepaymentwillbehandledbythecompanySoftWrapthatisourauthorizedpaymentprocessor.OnceyoumadethepaymentthesoftwarewillimmediatelybeupgradedtotheProEditionwithoutanyfurtheractionfromyourside.Carefullysave(andprint)theconfirmationyoureceiveasitcontainsyourpurchasereferencethatyoumightneedlaterifyouwanttoreinstallthesoftware.(Whenyouarerunningtheprogram,youcanalsoupgradeonlinebychoosingUpgradetoProEditionintheHelpmenu.)

IfyoupurchasedGameMakerbefore(andhence,haveanactivationcodeorapreviouspurchasereference)pressthebuttonEnterActivationCode.Youwillbebroughttoawebpagewhereyoucaneitherenteryouractivationcodeoryourpurchasereferencefromyourpreviouspayment.Hereyoucanalsoretrieveyourlicenseifyoulostit.AfteryoufilledinthecorrectinformationGameMakerwillbeupgradedtotheProEdition.NotethatyoumusthaveanInternetconnectionforactivation.(Whenyouarerunningtheprogram,youcanalsoupgradeonlinebychoosingEnterActivationCodeintheHelpmenu.)

Ifyoudon'twanttoupgradetotheProEditionatthisstage,pressthebuttonContinueUsingtheLiteEdition.

Gettingstarted

Creatingyourfirstgameisalwaysachallenge.Butifyouarewillingtoputalittlebitofeffortinit,itwillactuallyberathereasy.Youcanhaveitrunningwithinanhour.

EventhoughitisreallyeasytomakegameswithGameMakeryouwillneedtounderstandsomeofthebasicconcepts.TothisendyouarestronglyrecommendedtofollowthetutorialthatisshownwhenGameMakerisstarted.Ifyoudidremovethetutorialfromview,youcanalwaysmakeitvisibleagainbychoosingTutorialintheHelpmenu.

TheGlobalidea

BeforedelvingintothepossibilitiesofGameMakeritisgoodtogetafeelingfortheglobalideabehindtheprogram.GamescreatedwithGameMakertakeplaceinoneormorerooms.(Roomsareflat,not3D,buttheycancontain3D-lookinggraphics.)Intheseroomsyouplaceobjects,whichyoucandefineintheprogram.Typicalobjectsarethewalls,movingballs,themaincharacter,monsters,etc.Someobjects,likewalls,justsitthereanddon’tdoanything.Otherobjects,likethemaincharacter,willmovearoundandreacttoinputfromtheplayer(keyboard,mouse,andjoystick)andtoeachother.Forexample,whenthemaincharactermeetsamonsterhemightdie.ObjectsarethemostimportantingredientsofgamesmadewithGameMaker,soletustalkabitmoreaboutthem.

Firstofall,mostobjectsneedsomeimagetomakethemvisibleonthescreen.Suchimagesarecalledsprites.Aspriteisoftennotasingleimagebutasetofimagesthatareshownoneaftertheothertocreateananimation.Inthiswayitlookslikethecharacterwalks,aballrotates,aspaceshipexplodes,etc.Duringthegame,thespriteforaparticularobjectcanchange.(Sothecharactercanlookdifferentwhenitwalkstotheleftortotheright.)YoucancreateyouownspritesinGameMakeror

loadthemfromfiles(e.g.PNGfilesoranimatedGIF’s).ManyspritescomebundledwithGameMakerthatyoucanusefreeofchargeinyourgames.

Certainthingswillhappentoobjects.Suchhappeningsarecalledevents.Objectscantakecertainactionswheneventshappen.Therearealargenumberofdifferenteventsthatcantakeplaceandalargenumberofdifferentactionsthatyoucanletyourobjectstake.Forexample,thereisacreationeventwhentheobjectgetscreated.(Tobemoreprecise,whenaninstanceofanobjectgetscreated;therecanbemultipleinstancesofthesameobject.)Forexample,whenaballobjectgetscreatedyoucangiveitsomemotionactionsothatitstartsmoving.Whentwoobjectsmeet,yougetacollisionevent.Insuchacaseyoucanmaketheballstoporreversedirection.Youcanalsoplayasoundeffect.TothisendGameMakerletsyoudefinesounds.Whentheplayerpressesakeyonthekeyboardthereisakeyboardevent,andtheobjectcantakeanappropriateaction,likemovinginthedirectionindicated.Wehopeyougettheidea.Foreachobjectyoudesign,youcanindicateactionsforvariousevents;inthiswaydefiningthebehavioroftheobject.

Onceyouhavedefinedyourobjectsitistimetodefinetheroomsinwhichtheywilllive.Roomscanbeusedforlevelsinyourgameortocheckoutdifferentplaces.Thereareactionstomovefromoneroomtoanother.Rooms,firstofall,haveabackground.Thiscanbeasimplecolororanimage.SuchbackgroundimagescanbecreatedinGameMakeroryoucanloadthemfromfiles.(Thebackgroundcandoalotofthingsbutforthetimebeing,justconsideritassomethingthatmakestheroomslooknice.)Next,youcanplacetheobjectsintheroom.Youcanplacemultipleinstancesofthesameobjectinaroom.So,forexample,youneedtodefinejustonewallobjectandcanuseitatmanyplaces.Alsoyoucanhavemultipleinstancesofthesamemonsterobjects,aslongastheyhavethesamebehavior.

Nowyouarereadytorunthegame.Thefirstroomwillbeshownandobjectswillcometolifebecauseoftheactionsintheircreationevents.Theywillstartreactingtoeachotherduetoactionsincollisioneventsandtheycanreacttotheplayerusingtheactionsinkeyboardormouseevents.

Soinsummary,thefollowingthings(oftencalledresources)playacrucialrole:

objects:whicharethetrueentitiesinthegamerooms:theplaces(levels)inwhichtheobjectslivesprites:(animated)imagesthatareusedtorepresenttheobjectssounds:thesecanbeusedingames,eitherasbackgroundmusicoraseffectsbackgrounds:theimagesusedasbackgroundfortherooms

Thereareactuallyanumberofothertypesofresources:paths,scripts,fonts,andtimelines.Theseareonlyimportantformorecomplicatedgames.YouwillonlyseethemwhenyourunGameMakerinadvancedmode.Theywillbetreatedintheadvancedchapterslaterinthisdocument.

Theglobaluserinterface

WhenyoustartGameMakerthefollowingformisshown.NotethattheformmightinrealityalsoshowsomeGameMakernewsandthetutorialmightbevisibleattherightside.

(Actually,thisiswhatyouseewhenyourunGameMakerinsimplemode.Inadvancedmodeanumberofadditionalitemsareshown.)Attheleft,youseethedifferentresourcesmentionedabove:Sprites,Sounds,Backgrounds,Objects,Roomsandtwomore:GameInformationandGlobalGameSettings.Atthetopthereisthefamiliarmenuandtoolbar.Inthischapterwewilldescribebrieflythevariousmenuitems,buttons,etc.Inthelaterchapterswediscussanumberofthemindetail.Notethatmanythingscanbeachievedindifferentways:bychoosingacommandfromthemenu,byclickingabutton,orbyrightclickingonaresource.

Filemenu

Inthefilemenuyoucanfindsomeoftheusualcommandstoloadandsavefiles,plusafewspecialones:

New.Choosethiscommandtostartcreatinganewgame.Ifthecurrentgamewaschangedyouareaskedwhetheryouwanttosaveit.Thereisalsoatoolbarbuttonforthis.Open.Opensagamefile.GameMakerfileshavetheextension.gmk.Youcanalsoopenold.gm6files.(Ifyouwanttoopen.gmdfilescreatedwithversion5ofGameMakeryoumustselecttheappropriatefiletypeatthebottomofthedialog.Thesemightthoughnotworkcorrectlyinthenewversion.)Thereisatoolbarbuttonforthiscommand.YoucanalsoopenagamebydraggingthefileintotheGameMakerwindow.RecentFiles.Usethissubmenutoreopengamefilesyourecentlyopened.Save.Savesthegamedesignfileunderitscurrentname.Ifnonamewasspecifiedbefore,youareaskedforanewname.Youcanonlyusethiscommandwhenthefilewaschanged.Again,thereisatoolbarbuttonforthis.SaveAs.Savesthegamedesignfileunderadifferentname.Youareaskedforanewname.CreateExecutable.Onceyourgameisreadyyouwillprobablywanttogiveittootherstoplay.Usingthiscommandyoucancreateastand-aloneversionofyourgame.Thisissimplyanexecutablethatyoucangivetootherpeopletorun.AdvancedMode.WhenclickingonthiscommandGameMakerwillswitchbetweensimpleandadvancedmode.Inadvancedmodeadditionalcommandsandresourcesareavailable.Exit.Probablyobvious.PressthistoexitGameMaker.Ifyouchangedthecurrentgameyouwillbeaskedwhetheryouwanttosaveit.

Editmenu

Theeditmenucontainsanumberofcommandsthatrelatetothecurrentlyselectedresource(object,sprite,sound,etc.).Dependingonthetypeofresourcesomeofthecommandsmaynotbevisible.

Insertresource.Insertsanewinstanceofthecurrentlyselected

typeofresourcebeforethecurrentone.Aformwillopeninwhichyoucanchangethepropertiesoftheresource.Thiswillbetreatedindetailinthefollowingchapters.Duplicate.Makesacopyofthecurrentresourceandaddsit.Aformisopenedinwhichyoucanchangetheresource.Delete.Deletesthecurrentlyselectedresource(orgroupofresources).Becareful.Thiscannotbeundone.Youwill,though,bewarned.Rename.Givestheresourceanewname.Thiscanalsobedoneinthepropertyformfortheresource.Also,youcanselecttheresourceandthenclickonthename.Properties.Usethiscommandtobringuptheformtoedittheproperties.Notethatallthepropertyformsappearwithinthemainform.Youcaneditmanyofthematthesametime.Youcanalsoeditthepropertiesbydoubleclickingontheresource.

Notethatallthesecommandscanalsobegiveninadifferentway.Right-clickonaresourceorresourcegroup,andtheappropriatepop-upmenuwillappear.

Resourcesmenu

Inthismenu,youcancreatenewresourcesofeachofthedifferenttypes.Notethatforeachofthemthereisalsoabuttononthetoolbarandakeyboardshortcut.Alsoyoucanchangethegameinformationandtheglobalgamesettings.

Runmenu

Thismenuisusedtorunthegame.Therearetwowaystorunagame.

Runnormally.Runsthegameasitwouldnormallyrun.Thegameisruninthemostefficientwayandwilllookandactasinanexecutablegame.RuninDebugmode.Runsthegameindebugmode.Inthismode

youcancheckcertainaspectsofthegameandyoucanpauseandstepthroughit.Thisisusefulwhensomethinggoeswrongbutisabitadvanced.

Onceyourgameisfinished,youcancreateastand-aloneexecutableofthegameusingthecommandinthefilemenu.

Windowmenu

Inthismenuyoufindsomeoftheusualcommandstomanagethedifferentpropertywindowsinthemainform:

Cascade.Cascadeallthewindowssuchthateachofthemispartiallyvisible.ArrangeIcons.Arrangealltheiconifiedpropertywindows.(Usefulinparticularwhenresizingthemainform.)CloseAll.Closeallthepropertywindows,askingtheuserwhetherornottosavethechangesmade.

Helpmenu

Hereyoufindsomecommandstohelpyou:

Contents.Usethiscommandtoshowthishelpfile.Tutorials.UsethissubmenutoshowthedifferenttutorialsthatareprovidedwithGameMakertoteachyouhowtomakeyourfirstgames.UpgradetoProEdition.YoucanusethiscommandtoupgradetheLiteEditionofGameMakertotheProEditionOnline.TheProEditionhasmanyaditionalfeatures.EnterActivationCode.IfyoupurchasedGameMakerbefore(andhence,haveanactivationcodeorapreviouspurchasereference)youcanusethiscommandtoenteryourcode.Youwillbebroughttoawebpagewhereyoucaneitherenteryouractivationcodeoryourpurchasereferencefromyourpreviouspayment.News.HereyoucanseethemostrecentnewsaboutGameMaker.

Book.ThiscommandwillbringyoutoalocationonthewebsitewhereyoucanfindinformationabouttheGameMakerbook.MoreTutorials.Thiscommandwillbringyoutoalocationonthewebsitewhereyoucandownloadsomemoretutorials.Website.ConnectsyoutotheGameMakerwebsitewhereyoucanfindinformationaboutthemostrecentversionofGameMakerandcollectionsofgamesandresourcesforGameMaker.Forum.ThiscommandwillbringyoutotheforumwhereusershelpeachotherwithmanyaspectsofGameMaker.Wiki.ThiscommandwillbringyoutotheGameMakerwikiwhereyoucanfindplentyofinformationabouttheuseofGameMaker.AboutGameMaker.GivessomeshortinformationaboutthisversionofGameMaker.

Theresourceexplorer

Attheleftofthemainformyoufindtheresourceexplorer.Hereyouwillseeatree-likeviewofallresourcesinyourgame.ItworksinthesamewayastheWindowsExplorer,andyouaremostlikelyfamiliarwithit.Ifanitemhasa+signinfrontofityoucanclickonthesigntoseetheresourcesinsideit.Byclickingonthe-signthesedisappearagain.Youcanchangethenameofaresource(exceptthetoplevelones)byselectingit(withasingleclick)andthenclickingonthename.Doubleclickonaresourcetoedititsproperties.UsetherightmousebuttontoaccessthesamecommandsasintheEditmenu.

Youcanchangetheorderoftheresourcesbyclickingonthemwiththemouseandholdingthemousebuttonpressed.Nowyoucandragtheresourcetotheappropriateplace.(Ofcoursetheplacemustbecorrect.Youcannotdragasoundintothelistofsprites.)

Definingsprites

Spritesarethevisualrepresentationsofalltheobjectsinthegame.Aspriteiseitherasingleimage,drawnwithanydrawingprogramyoulike,orasetofimagesthat,whenplayedoneafteranother,lookslikeananimatedmotion.Forexample,thefollowingfourimagesformaspriteforacharactermovingtotheright.

Whenyoumakeagameyounormallystartbycollectingasetofnicespritesfortheobjectsinyourgame.AconsiderablenumberofusefulspritesisbundledwithGameMaker.OthercollectionsofinterestingspritescanbefoundontheGameMakerwebsite.Manymorespritescanbefoundontheweb,normallyintheformofpngoranimatedgiffiles.

Tocreateasprite,choosetheitemCreateSpritefromtheResourcesmenu,orusethecorrespondingbuttononthetoolbar.Thefollowingformwillpopup.

Atthetop-leftyoucanindicatethenameofthesprite.Allsprites(andallotherresources)haveaname.It'sbesttogiveeachspriteadescriptivename.Makesureallresourcesgetdifferentnames.Eventhoughthisis

notstrictlyrequired,youarestronglyadvisedtouseonlylettersanddigitsandtheunderscoresymbol(_)inanameofasprite(andanyotherresource)andtoletitstartwithaletter.Inparticulardon'tusethespacecharacter.Thiswillbecomeimportantonceyoustartusingcode.

Toloadasprite,clickonthebuttonLoadSprite.Aspecialfiledialogopensinwhichyoucanchoosethesprite:

Theleftpartlookslikethestandardfileselectorinwhichyoucanselectthespritethatyouwant.Attherightyougetapreviewoftheanimatedspriteandsomeinformationaboutit.Hereyoucanalsoindicatethatyouwanttomakethespriteopaque(thatis,removeanytransparentparts),whethertoremovethebackground,makingittransparent(default),andwhethertosmooththeedgesofthesprite,whichcanimproveitsappearance.WhenyouarehappywiththeresultpressOpentoloadthesprite.

GameMakercanloadmanydifferentgraphicsfiles.Whenyouloadananimatedgif,thedifferentsubimagesformthespriteimages.Whenthefilenameendswith_stripXX,withXXanumber,itisconsideredtocontainastripofXXsubimagesnexttoeachother(notforgiffiles).Forexample,aimagefilewithnameball_strip4.pngisassumedtocontain4subimages.

Oncethespriteisloadedthefirstsubimageisshownontheright.When

therearemultiplesub-images,youcancyclethroughthemusingthearrowbuttons.

WiththebuttonEditSpriteyoucaneditthesprite,orevencreateacompletelynewsprite.GameMakerhasanextensivebuilt-inspriteandimageeditor.FormoreinformationseethesectionsonEditingyourspritesandonEditingindividualsubimages.

Soundsandmusic

Mostgameshavecertainsoundeffectsandsomebackgroundmusic.ManyusefulsoundeffectscanbefoundontheGameMakerwebsite.Manymorecanbefoundonotherplacesontheweb.

Tocreateasoundresourceinyourgame,usetheitemCreateSoundintheResourcesmenuorusethecorrespondingbuttononthetoolbar.Thefollowingformwillpopup.

Toloadasound,pressthebuttonlabeledLoadSound.Afileselectordialogpopsupinwhichyoucanselectthesoundfile.Therearetwotypesofsoundfiles,wavefilesandmidifiles.Wavefilesareusedforshortsoundeffects.Theyusealotofmemorybutplayinstantaneously.Usetheseforallthesoundeffectsinyourgame.Midifilesdescribemusicinadifferentway.Asaresulttheyusealotlessmemory,buttheyarelimitedtoinstrumentalbackgroundmusic.Also,defaultonlyonemidisoundcanplayatanytime.

Onceyouloadamusicfileyoucanlistentothesoundusingtheplaybutton.ThereisalsoabuttonSaveSoundtosavethecurrentsoundtoafile.Thisbuttonisnotreallyrequiredbutyoumightneeditifyoulosttheoriginalsound.

Backgrounds

Thethirdtypeofbasicresourceisbackgrounds.Backgroundsareusuallylargeimagesthatareusedasbackgrounds(orforegrounds)fortheroomsinwhichthegametakesplace.Oftenbackgroundimagesaremadeinsuchawaythattheycantileanareawithoutvisualcracks.Inthiswayyoucanfillthebackgroundwithsomepattern.AnumberofsuchusefulbackgroundsarebundledwithGameMaker.OtherscanbefoundontheGameMakerwebsite.Manymorecanbefoundatotherplacesontheweb.

Tocreateabackgroundresourceinyourgame,usetheitemCreateBackgroundintheResourcesmenuorusethecorrespondingbuttononthetoolbar.Thefollowingformwillpopup.

Atthetop-leftyoucanindicatethenameofthebackground.Youarestronglyrecommendedtogiveeverybackground(andotherresource)adescriptivename.

PressthebuttonLoadBackgroundtoloadabackgroundimage.Afileselectorisshowninwhichyoucanselectthebackgroundyouwant.Attherightofthedialogyoucanindicatewhetheryouwanttomakethebackgroundopaque(thatis,removeanytransparentparts),whethertoremovethebackground,makingittransparent(defaultnot),andwhethertosmooththeedgesofthebackground,whichcanimproveitsappearancewhenitispartiallytransparent.Whenyouarehappywiththe

resultpressOpentoloadthebackground.GameMakersupportsmanyimageformats.Backgroundimagescannotbeanimated!

YoucanchangethebackgroundorcreateanewoneusingthebuttonEditBackground.Thiswillopenanextensiveimageeditor.ForinformationonhowtousetheimageeditorseethesectiononEditingimages.

Becarefulwithlargebackgrounds.Someoldgraphicscardscannothandleimagesthatarelargerthanthescreen.Sopreferablykeepyourbackgroundimagessmallerthan1024x1024.

Definingobjects

Withtheresourcesyouhaveseensofaryoucanaddsomeniceimagesandsoundstothegame,buttheydon'tdoanything.WenowcometothemostimportantresourceofGameMaker,theobjects.Objectsareentitiesinthegamethatdothings.Mostofthetimetheyhaveaspriteasagraphicalrepresentationsothatyouseethem.Theyhavebehaviorbecausetheycanreacttocertainevents.Allthingsyouseeinthegame(exceptforthebackground)areobjects.(Ortobemoreprecise,theyareinstancesofobjects.)Thecharacters,themonsters,theballs,thewalls,etc.areallobjects.Theremightalsobecertainobjectsthatyoudon'tseebutwhichcontrolcertainaspectsofthegameplay.

Pleaserealizethedifferencebetweenspritesandobjects.Spritesarejust(animated)imagesthatdon'thaveanybehavior.Objectsnormallyhaveaspritetorepresentthembutobjectshavebehavior.Withoutobjectsthereisnogame!

Alsorealizethedifferencebetweenobjectsandinstances.Anobjectdescribesacertainentity,e.g.amonster.Therecanbemultipleinstancesofthisobjectinthegame.Whenwetalkaboutaninstancewemeanoneparticularinstanceoftheobject.Whenwetalkaboutanobjectwemeanalltheinstancesofthisobject.

Tocreateanobjectinyourgame,chooseCreateObjectfromtheResourcesmenu.Thefollowingformwillappear:

Thisisrathercomplex.Attheleftthereissomegeneralinformationabouttheobject.Inthemiddlethereisthelistofeventsthatcanhappentotheobject.Attherighttherearethedifferentactionstheobjectcanperform.Eventsandactionswillbediscussedinthecomingchapters.

Asalways,youcan(andshould)giveyourobjectaname.Nextyoucanchoosethespritefortheobject.Tothisend,clickwiththeleftmousebuttononthespriteboxorthemenubuttonnexttoit.Amenuwillpop-upwithalltheavailablesprites.Selecttheoneyouwanttousefortheobject.Ifyoudonothaveaspriteyet,youcanclickthebuttonNewtocreateanewspriteresourceandchangeit.Also,whenyouselectaresourcetherewillbeabuttonEditherethatyoucanusetochangethesprite.Thisisfasterthanfirstfindingtheresourceinthelistofresourcesandthenindicatingyouwanttoeditit.

Belowthistherearetwocheckboxes.Visibleindicateswhetherinstancesofthisobjectarevisible.Clearly,mostobjectsarevisible,butsometimesitisusefultohaveinvisibleobjects.Forexample,youcanusethemforwaypointsforamovingmonster.Invisibleobjectswillreacttoeventsandotherinstancesdocollidewiththem.TheboxlabeledSolidindicateswhetherthisisasolidobject(likeawall).Collisionswithsolidobjectsaretreateddifferentlyfromcollisionswithnon-solidobjects.YouarestronglyadvisedtouseSolidonlyforobjectthatarenotmoving.

Events

GameMakeruseswhatiscalledaneventdrivenapproach.Thisworksasfollows.Wheneversomethinghappensinthegametheinstancesoftheobjectsgetevents(kindofmessagestellingthatsomethinghashappened).Theinstancescanthenreacttothesemessagesbyexecutingcertainactions.Foreachobjectyoumustindicatetowhicheventsitrespondsandwhatactionsitmustperformwhentheeventoccurs.Thismaysoundcomplicatedbutisactuallyveryeasy.Firstofall,formosteventstheobjectdoesnothavetodoanything.Fortheeventswheresomethingmustbedoneyoucanuseaverysimpledrag-and-dropapproachtoindicatetheactions.

Inthemiddleoftheobjectpropertyformthereisalistofeventstowhichtheobjectmustreact.Initiallyitisempty.YoucanaddeventstoitbypressingthebuttonlabeledAddEvent.Aformwillappearwithalldifferenttypesofevents.Hereyouselecttheeventyouwanttoadd.Sometimesamenupopsupwithextrachoices.Forexample,forthekeyboardeventyoumustselectthekey.Belowyoufindacompletelistofthedifferenteventsplusdescriptions.Oneeventinthelistwillbeselected.Thisistheeventwearecurrentlychanging.Youcanchangetheselectedeventbyclickingonit.Attherighttherearealltheactionsrepresentedbylittleicons.Theyaregroupedinanumberoftabbedpages.Inthenextchapteryouwillfinddescriptionsofalltheactionsandwhattheydo.Betweentheeventsandtheactionsthereistheactionlist.Thislistcontainstheactionsthatmustbeperformedforthecurrentevent.Toaddactionstothelist,dragthemwithyourmousefromtherighttothelist.Theywillbeplacedbeloweachother,withashortdescription.Foreachactionyouwillbeaskedtoprovideafewparameters.Thesewillalsobedescribedinthenextchapter.Soafteraddingafewactionsthesituationmightlookasfollows:

Nowyoucanstartaddingactionstoanotherevent.Clickonthecorrecteventwiththeleftmousebuttontoselectitanddragactionsinthelist.

Youcanchangetheorderoftheactionsinthelistagainusingdrag-and-drop.Ifyouholdthe<Alt>keywhiledragging,youmakeacopyoftheaction.Youcanevenusedrag-and-dropbetweenactionlistsfordifferentobjects.Whenyouclickwiththerightmousebuttononanaction,amenuappearsinwhichyoucandeletetheselectedaction(canalsobedonebyusingthe<Del>key)orcopyandpasteactions.(Youcanselectmultipleactionsforcutting,copying,ordeletingbyholdingthe<Shift>keyof<Ctrl>key.Press<Ctrl><A>toselectallactions.)Whenyouholdyourmouseatrestaboveanaction,alongerdescriptionisgivenoftheaction.Seethenextchapterformoreinformationonactions.

TodeletethecurrentlyselectedeventtogetherwithallitsactionspressthebuttonlabeledDelete.(Eventswithoutanyactionswillautomaticallybedeletedwhenyouclosetheformsothereisnoneedtodeletethemmanually.)Ifyouwanttoassigntheactionstoadifferentevent(forexample,becauseyoudecidedtouseadifferentkeyforthem)pressthebuttonlabeledChangeandpicktheneweventyouwant.(Theeventshouldnotbedefinedalready!)Usingthemenuthatpopsupwhenright-clickingontheeventlist,youcanalsoduplicateanevent,thatis,addaneweventwiththesameactions.

Asindicatedabove,toaddanevent,pressthebuttonAddEvent.Thefollowingformpopsup:

Hereyouselecttheeventyouwanttoadd.Sometimesamenupopsupwithextrachoices.Hereisadescriptionofthevariousevents.(Againrememberthatyounormallyuseonlyafewofthem.)

CreateeventThiseventhappenswhenaninstanceoftheobjectiscreated.Itisnormallyusedtosettheinstanceinmotionand/ortosetcertainvariablesfortheinstance.

DestroyeventThiseventhappenswhentheinstanceisdestroyed.Tobeprecise,ithappensjustbeforeitisdestroyed,sotheinstancedoesstillexistwhentheeventisexecuted!Mostofthetimethiseventisnotusedbutyoucanforexampleuseittochangethescoreortocreatesomeotherobject.

AlarmeventsEachinstancehas12alarmclocks.Youcansetthesealarmclocksusingcertainactions(seenextchapter).Thealarmclockthenticksdownuntilitreaches0atwhichmomentthealarmeventisgenerated.Toindicatetheactionsforagivenalarmclock,youfirstneedtoselectitinthemenu.Alarmclocksareveryuseful.Youcanusethemtoletcertainthingshappenfromtimetotime.Forexampleamonstercanchangeitsdirectionofmotionevery20steps.(Insuchcasesoneoftheactionsintheeventmustsetthealarmclockagain.)

StepeventsThestepeventhappenseverystepofthegame.Hereyoucanputactionsthatneedtobeexecutedcontinuously.Forexample,ifoneobjectshouldfollowanother,hereyoucanadaptthedirectionofmotiontowardstheobjectwearefollowing.Becarefulwiththiseventthough.Don'tput

manycomplicatedactionsinthestepeventofobjectsofwhichtherearemanyinstances.Thismightslowthegamedown.Tobemoreprecise,therearethreedifferentstepevents.Normallyyouonlyneedthedefaultone.Butusingthemenuyoucanalsoselectthebeginstepeventandtheendstepevent.Thebeginstepeventisexecutedatthebeginningofeachstep,beforeanyothereventstakeplace.Thenormalstepeventisexecutedjustbeforetheinstancesareputintheirnewpositions.Theendstepeventisexecutedattheendofthestep,justbeforethedrawing.Thisistypicallyusedtochangethespritedependingonthecurrentdirection.

CollisioneventsWhenevertwoinstancescollide(thatis,theirspritesoverlap)acollisioneventappears.Well,tobeprecisetwocollisioneventoccur;oneforeachinstance.Theinstancecanreacttothiscollisionevent.Tothisend,fromthemenuselecttheobjectwithwhichyouwanttodefinethecollisionevent.Nextyouplacetheactionshere.

Thereisadifferenceinwhathappenswhentheinstancecollideswithasolidobjectoranon-solidobject.Firstofall,whentherearenoactionsinthecollisionevent,nothinghappens.Thecurrentinstancesimplykeepsonmoving;evenwhentheotherobjectissolid.Whenthecollisioneventcontainsactionsthefollowinghappens:

Whentheotherobjectissolid,theinstanceisplacedbackatitspreviousplace(beforethecollisionoccurs).Thentheeventisexecuted.Finally,theinstanceismovedtoitsnewposition.Soiftheevente.g.reversesthedirectionofmotion,theinstancebouncesagainstthewallwithoutstopping.Ifthereisstillacollision,theinstanceiskeptatitspreviousplace.Soiteffectivelystopsmoving.

Whentheotherobjectisnotsolid,theinstanceisnotputback.Theeventissimplyexecutedwiththeinstanceatitscurrentposition.Also,thereisnosecondcheckforacollision.Ifyouthinkaboutit,thisisthelogicalthingthatshouldhappen.Becausetheobjectisnotsolid,wecansimplymoveoverit.Theeventnotifiesusthatthisishappening.

Therearemanyusesforthecollisionevent.Instancescanuseitto

bounceagainstwalls.Youcanuseittodestroyobjectswhen,forexample,theyarehitbyabullet.

KeyboardeventsWhentheplayerpressesakey,akeyboardeventhappensforallinstancesofallobjects.Thereisadifferenteventforeachkey.Inthemenuyoucanpickthekeyforwhichyouwanttodefinethekeyboardeventandnextdragactionsthere.Clearly,onlyafewobjectsneedeventsforonlyafewkeys.Yougetaneventineverystepaslongastheplayerkeepsthekeydepressed.Therearetwospecialkeyboardevents.Oneiscalled<Nokey>.Thiseventhappensineachstepwhennokeyispressed.Thesecondoneiscalled<Anykey>andhappenswhateverkeyispressed.Whentheplayerpressesmultiplekeys,theeventsforallthekeyspressedhappen.Notethatthekeysonthenumerickeypadonlyproducethecorrespondingeventswhen<NumLock>ispressed.

MouseeventsAmouseeventhappensforaninstancewheneverthemousecursorliesinsidethespriterepresentingtheinstance.Dependingonwhichmousebuttonsarepressedyougetthenobutton,leftbutton,rightbutton,ormiddlebuttonevent.Themousebuttoneventsaregeneratedineachstepaslongastheplayerkeepsthemousebuttonpressed.Thepresseventsareonlygeneratedoncewhenthebuttonispressed.Thereleaseeventsareonlygeneratedwhenthebuttonisreleased.Notethattheseeventsonlyoccurwhenthemouseisabovetheinstance.Ifyouwanttoreacttomousepressorreleaseeventsatanarbitraryplace,usetheglobalmouseeventsthatcanbefoundinasubmenu.Therearetwospecialmouseevents.Themouseentereventhappenswhenthemouseenterstheinstance.Themouseleaveeventhappenswhenthemouseleavestheinstance.Theseeventsaretypicallyusedtochangetheimageorplaysomesound.Mousewheelupandmousewheeldowneventshappenwhentheusermovesthemousewheel.Finallythereareanumberofeventsrelatedtothejoystick.Youcanindicateactionsforthefourmaindirectionsofthejoystick(inadiagonaldirectionbotheventshappen).Alsoyoucandefineactionsforupto8joystickbuttons.Youcandothisbothfortheprimaryjoystickandthesecondaryjoystick.

Otherevents

Thereareanumberofothereventsthatcanbeusefulincertaingames.Theyarefoundinthismenu.Thefollowingeventscanbefoundhere:

Outsideroom:Thiseventhappenswhentheinstanceliescompletelyoutsidetheroom.Thisistypicallyagoodmomenttodestroyit.Intersectboundary:Thiseventhappenswhentheinstanceintersectstheboundaryoftheroom,thatis,itlies(atleast)partiallyoutsidetheroom.Views:Hereyoufindanumberofeventsthatareusefulwhenyouuseviewsinyourrooms.Theseeventstestwhethertheinstanceliescompletelyoutsideaparticularvieworinteresectstheviewboundary.Gamestart:Thiseventhappensforallinstancesinthefirstroomwhenthegamestarts.Ithappensbeforetheroomstartevent(seebelow)butafterthecreationeventsfortheinstancesintheroom.Thiseventistypicallydefinedinonlyone"controller"objectandisusedtostartsomebackgroundmusicandtoinitializesomevariables,orloadsomedata.Gameend:Theeventhappenstoallinstanceswhenthegameends.Againtypicallyjustoneobjectdefinesthisevent.Itisforexampleusedtostorecertaindatainafile.Roomstart:Thiseventhappensforallinstancesinitiallyinaroomwhentheroomstarts.Ithappensafterthecreationevents.Roomend:Thiseventhappenstoallexistinginstanceswhentheroomends.Nomorelives:GameMakerhasabuilt-inlivessystem.Thereisanactiontosetandchangethenumberoflives.Wheneverthenumberoflivesbecomeslessthanorequalto0,thiseventhappens.Itistypicallyusedtoendorrestartthegame.Nomorehealth:GameMakerhasabuilt-inhealthsystem.Thereisanactiontosetandchangethehealth.Wheneverthehealthbecomeslessthanorequalto0,thiseventhappens.Itistypicallyusedtoreducethenumberoflivesortorestartthegame.Animationend:Asindicatedabove,ananimationconsistsofanumberofimagesthatareshownoneaftertheother.Afterthelastoneisshownwestartagainwiththefirstone.Theeventhappensat

preciselythatmoment.Asanexample,thiscanbeusedtochangetheanimation,ordestroytheinstance.Endofpath:Thiseventhappenswhentheinstancefollowsapathandtheendofthepathisreached.Closebutton:Thiseventhappenswhentheuserclicksontheclosebuttonofthewindow.ThisonlyhappenswhendisablinginthegamesettingstheoptiontohavetheclosebuttonbehaveastheEscapekey.Userdefined:Thereare16oftheseevents.Theynormallyneverhappenunlessyouyourselfcallthemfromapieceofcode.

DraweventInstances,whenvisible,drawtheirspriteineachsteponthescreen.Whenyouspecifyactionsinthedrawingevent,thespriteisnotdrawn,buttheseactionsareexecutedinstead.Thiscanbeusedtodrawsomethingotherthanthesprite,orfirstmakesomechangestospriteparameters.Thereareanumberofdrawingactionsthatareespeciallymeantforuseinthedrawingevent.Notethatthedrawingeventisonlyexecutedwhentheobjectisvisible.Alsonotethat,independentofwhatyoudraw,collisioneventsarebasedonthespritethatisassociatedwiththeinstance.

KeyPresseventsThiseventissimilartothekeyboardeventbutithappensonlyoncewhenthekeyispressed,ratherthancontinuously.Thisisusefulwhenyouwantanactiontohappenonlyonce.

KeyReleaseeventsThiseventissimilartothekeyboardeventbutithappensonlyoncewhenthekeyisreleased,ratherthancontinuously.

InsomesituationitisimportanttounderstandtheorderinwhichGameMakerprocessestheevents.Thisisasfollows:

BeginstepeventsAlarmeventsKeyboard,Keypress,andKeyreleaseeventsMouseevents

Normalstepevents(nowallinstancesaresettotheirnewpositions)CollisioneventsEndstepeventsDrawevents

Thecreate,destroy,andothereventsareperformedwhenthecorrespondingthingshappen.

Actions

ActionsindicatethethingsthathappeninagamecreatedwithGameMaker.Actionsareplacedineventsofobjects.Whenevertheeventtakesplacetheseactionsareperformed,resultingincertainbehaviorfortheinstancesoftheobject.Therearealargenumberofdifferentactionsavailableanditisimportantthatyouunderstandwhattheydo.Inthischapterwedescribetheactionsavailableinsimplemode.NotethatanumberoftheseactionsareonlyavailableintheProEditionofGameMaker.Thiswillbeindicated.

Alltheactionsarefoundinthetabbedpagesattherightoftheobjectpropertyform.Therearesixsetsofactions.Youselectthesetyouwantbyclickingonthecorrecttab.Whenyouholdyoumouseaboveoneoftheactions,ashortdescriptionisshowntoremindyouofitsfunction.

Letusbrieflyrepeat:Toputanactioninanevent,justdragitfromthetabbedpagestotheactionlist.Youcanchangetheorderinthelist,againusingdragging.Holdingthe<Alt>keywhiledraggingmakesacopyoftheaction.(Youcandragandcopyactionsbetweenthelistsindifferentobjectpropertyforms.)Usetherightmousebuttonandselectthecorrectmenuitemtoremoveactions(orusethe<Del>key)andtocopyandpasteselectedactions.

Whenyoudropanactionintheactionlist,awindowwillpop-upmostofthetime,inwhichyoucanfillincertainparametersfortheaction.Theparameterswillbedescribedbelowwhendescribingtheactions.Twotypesofparametersappearinmanyactionssowewilldescribethesehere.Atthetopyoucanindicatetowhichinstancetheactionapplies.Thedefaultisself,whichistheinstanceforwhichtheactionisperformed.Mostofthetime,thisiswhatyouwant.Inthecaseofacollisionevent,youcanalsospecifytoapplytheactiontotheotherinstanceinvolvedinthecollision.Forinstance,inthiswayyoucandestroytheotherinstance.Finally,youcanchoosetoapplytheactiontoallinstancesofaparticularobject.Inthiswayyoucouldchangeallred

ballsintoblueballs.ThesecondtypeofparameteristheboxlabeledRelative.Bycheckingthisbox,thevaluesyoutypeinarerelativetothecurrentvalues.Forexample,inthiswayyoucanaddsomethingtothecurrentscore,ratherthanchangingthecurrentscoretothenewvalue.Theotherparameterswillbedescribedbelow.Youcanlaterchangetheparametersbydoubleclickingontheaction.

Informationonthedifferentactionscanbefoundinthefollowingpages:

MoveActionsMainActions,Set1MainActions,Set2ControlActionsScoreActionsDrawActionsUsingVariablesandExpressions

Moveactions

Thefirstsetofactionsconsistsofthoserelatedtomovementofobjects.Thefollowingactionsexist:

MoveFixedUsethisactiontostarttheinstancemovinginaparticulardirection.Youcanindicatethedirectionusingthebuttonswiththearrowsonit.Usethemiddlebuttontostopthemotion.Alsoyouneedtospecifythespeedofthemotion.Thisspeedisgiveninpixelsperstep.Preferablydon'tusenegativespeeds.Youcanspecifymultipledirections.Inthiscasearandomchoiceismade.Inthiswayyoucanletamonsterstartmovingeitherleftorright.

MoveFreeThisisthesecondwaytospecifyamotion.Hereyoucanindicateaprecisedirection.Thisisananglebetween0and360degrees.0meanstotheright.Thedirectioniscounter-clockwise.Soforexample90indicatesanupwarddirection.Ifyouwantanarbitrarydirection,youcantyperandom(360).Asyouwillseebelowthefunctionrandomgivesarandomnumbersmallerthantheindicatedvalue.AsyoumighthavenoticedthereisacheckboxlabeledRelative.Ifyoucheckthis,thenewmotionisaddedtothepreviousone.Forexample,iftheinstanceismovingupwardsandyouaddsomemotiontotheleft,thenewmotionwillbeupwardstotheleft.

MoveTowardsThisactiongivesathirdwaytospecifyamotion.Youindicateapositionandaspeedandtheinstancestartsmovingwiththespeedtowardstheposition.(Itwon'tstopattheposition!)Forexample,ifyouwantabullettoflytowardsthepositionofthespaceshipyoucanuseaspositionspaceship.x,spaceship.y.(Youwilllearnmoreabouttheuseofvariableslikethesebelow.)IfyouchecktheRelativebox,youspecifythepositionrelativetothecurrentpositionoftheinstance.(Thespeedisnottakenrelatively!)

SpeedHorizontalThespeedofaninstanceconsistsofahorizontalpartandaverticalpart.Withthisactionyoucanchangethehorizontalspeed.Apositivehorizontalspeedmeansamotiontotheright.Anegativeonemeansamotiontotheleft.Theverticalspeedwillremainthesame.Userelativetoincreasethehorizontalspeed(ordecreaseitbyprovidinganegativenumber).

SpeedVerticalInasimilarway,withthisactionyoucanchangetheverticalspeedoftheinstance.

SetGravityWiththisactionyoucancreategravityforthisparticularobject.Youspecifyadirection(anglebetween0and360degrees)andaspeed,andineachstepthisamountofspeedinthegivendirectionisaddedtothecurrentmotionoftheobjectinstance.Normallyyouneedaverysmallspeedincrement(like0.01).Typicallyyouwantadownwarddirection(270degrees).IfyouchecktheRelativeboxyouincreasethegravityspeedanddirection.Notethat,contrarytoreallife,differentobjectcanhavedifferentgravitydirections.

ReverseHorizontalWiththisactionyoureversethehorizontalmotionoftheinstance.Thiscanforexamplebeusedwhentheobjectcollideswithaverticalwall.

ReverseVerticalWiththisactionyoureversetheverticalmotionoftheinstance.Thiscanforexamplebeusedwhentheobjectcollideswithahorizontalwall.

SetFrictionFrictionslowsdowntheinstanceswhentheymove.Youspecifytheamountoffriction.Ineachstepthisamountissubtractedfromthespeeduntilthespeedbecomes0.Normallyyouwantaverysmallnumberhere(like0.01).

JumptoPosition

Usingthisactionyoucanplacetheinstanceinaparticularposition.Yousimplyspecifythex-andy-coordinate,andtheinstanceisplacedwithitsreferencepointonthatposition.IfyouchecktheRelativebox,thepositionisrelativetothecurrentpositionoftheinstance.Thisactionisoftenusedtocontinuouslymoveaninstance.Ineachstepweincrementthepositionabit.

JumptoStartThisactionplacestheinstancebackatthepositionwhereitwascreated.

JumptoRandomThisactionmovestheinstancetoarandompositionintheroom.Onlypositionsarechosenwheretheinstancedoesnotintersectanysolidinstance.Youcanspecifythesnappingused.Ifyouspecifypositivevalues,thecoordinateschosenwithbeintegermultiplesoftheindicatedvalues.Thiscouldforexamplebeusedtokeeptheinstancealignedwiththecellsinyourgame(ifany).Youcanspecifyaseparatehorizontalsnappingandverticalsnapping.

AligntoGridWiththisactionyoucanroundthepositionoftheinstancetoagrid.Youcanindicateboththehorizontalandverticalsnappingvalue(thatis,thesizeofthecellsofthegrid).Thiscanbeveryusefultomakesurethatinstancesstayonagrid.

WrapScreenWiththisactionyoucanletaninstancewraparound,thatis,whenitleavesononesideoftheroomitreappearsattheotherside.ThisactionisnormallyusedintheOutsideevent.Notethattheinstancemusthaveaspeedforwrappingtowork,causethedirectionofwrappingisbasedonthedirectionofthemotion.Youcanindicatewhethertowraponlyhorizontal,onlyvertical,orinbothdirections.

MovetoContactWiththisactionyoucanmovetheinstanceinagivendirectionuntilacontactpositionwithanobjectisreached.Iftherealreadyisacollisionatthecurrentpositiontheinstanceisnotmoved.Otherwise,theinstanceis

placedjustbeforeacollisionoccurs.Youcanspecifythedirectionbutalsoamaximaldistancetomove.Forexample,whentheinstanceisfallingyoucanmoveamaximaldistancedownuntilanobjectisencountered.Youcanalsoindicatewhethertoconsidersolidobjectonlyorallobjects.Youtypicallyputthisactioninthecollisioneventtomakesurethattheinstancestopsincontactwiththeotherinstanceinvolvedinthecollision.

BounceWhenyouputthisactioninthecollisioneventwithsomeobject,theinstancebouncesbackfromthisobjectinanaturalway.Ifyousettheparameterprecisetofalse,onlyhorizontalandverticalwallsaretreatedcorrectly.Whenyousetprecisetotruealsoslanted(andevencurved)wallsaretreatedcorrectly.Thisisthoughslower.Alsoyoucanindicatewhethertobounceonlyagainstsolidobjectsoragainstallobjects.Pleaserealizethatthebounceisnotcompletelyaccuratebecausethisdependsonmanyproperties.Butinmanysituationstheeffectisgoodenough.

Mainactions,set1

Thefollowingsetofactionsdealswithcreating,changing,anddestroyinginstancesofobjects,withsounds,andwithrooms.

CreateInstanceWiththisactionyoucancreateaninstanceofanobject.Youspecifywhichobjecttocreateandthepositionforthenewinstance.IfyouchecktheRelativebox,thepositionisrelativetothepositionofthecurrentinstance.Creatinginstancesduringthegameisextremelyuseful.Aspaceshipcancreatebullets;abombcancreateanexplosion,etc.Inmanygamesyouwillhavesomecontrollerobjectthatfromtimetotimecreatesmonstersorotherobjects.Forthenewlycreatedinstancethecreationeventisexecuted.

CreateMovingThisactionworksthesameastheactionabovebutwithtwoadditionalfields.Youcannowalsospecifythespeedanddirectionofthenewlycreatedinstance.NotethatifyouchecktheRelativebox,onlythepositionisrelative,notthespeedanddirection.Forexample,tomakeabulletmoveinthedirectionofthepersonshootingyouhavetousealittletrick.Aspositionuse0,0andcheckRelative.Asdirectionweneedthecurrentdirectionoftheinstance.Thiscanbeobtainedbytypingintheworddirection.(Thisactuallyisavariablethatalwaysindicatesthecurrentdirectioninwhichtheinstanceismoving.)

CreateRandomThisactionletsyoucreateaninstanceofoneoutoffourobjects.Youspecifythefourobjectsandtheposition.Aninstanceofoneofthesefourobjectsiscreatedatthegivenposition.IfyouchecktheRelativebox,thepositionisrelativetothepositionofthecurrentinstance.IfyouneedachoiceoutoflessthanfourobjectsyoucanuseNoObjectforsomeofthem.Thisisforexampleusefultogeneratearandomenemyatalocation.

ChangeInstance

Withthisactionyoucanchangethecurrentinstanceintoaninstanceofanotherobject.Soforexample,youcanchangeaninstanceofabombintoanexplosion.Allsettings,suchasthemotionandthevalueofvariables,willstaythesame.Youcanindicatewhetherornottoperformthedestroyeventforthecurrentobjectandthecreationeventforthenewobject.

DestroyInstanceWiththisactionyoudestroythecurrentinstance.Thedestroyeventfortheinstanceisexecuted.

DestroyatPositionWiththisactionyoudestroyallinstanceswhoseboundingboxcontainsagivenposition.Thisisuseful,forexample,whenyouuseanexplodingbomb.WhenyouchecktheRelativeboxthepositionistakenrelativetothepositionofthecurrentinstance.

ChangeSpriteUsethisactiontochangethespritefortheinstance.Youindicatewhichnewsprite.Youcanalsoindicatewithsubimagemustbeshown.Normallyyouwoulduse0forthis(thefirstsubimage)unlessyouwanttoseeaparticularsubimage.Use-1ifyoudonotwanttochangethecurrentsubimageshown.Finallyyouchangethespeedoftheanimationofthesubimages.Ifyouonlywanttoseeaparticularsubimage,setthespeedto0.Ifthespeedislargerthanonesubimageswillbeskipped.Ifitissmallerthan1subimageswillbeshownmultipletimes.Don'tuseanegativespeed.Changingspritesisanimportantfeature.Forexample,oftenyouwanttochangethespriteofacharacterdependingonthedirectioninwhichitwalks.Thiscanbeachievedbymakingdifferentspritesforeachofthe(four)directions.Withinthekeyboardeventsforthearrowkeysyousetthedirectionofmotionandthesprite.

TransformSpriteUsethisactiontochangethesizeandorientationofthespritefortheinstance.Usethescalefactorstomakeitlargerorsmaller.Theanglegivesthecounter-clockwiseorientationofthesprite.Forexample,tomakethespriteorientedinthedirectionofmotionuseasavalue

direction.Forexample,thisisusefulforacar.Youcanalsoindicatewhetherthespriteshouldbemirroredhorizontallyand/orflippedvertically.ThisactionisonlyavailableintheProEdition.

ColorSpriteNormallythespriteisdrawnasitisdefined.Usingthisactionyoucanchangethecolorofthesprite.Thiscolorisblendedwiththesprite,thatis,itiscombinedwiththecolorsofthesprite.Ifyouwanttodrawaspriteindifferentcolorsyoubetterdefinethespriteinblackandwhiteandusetheblendcolortosettheactualcolor.Youcanalsoindicateanalphatransparency.Withavalueof1thespriteisopaque.Withavalueof0itiscompletelytransparent.Withavalueinbetweenyouwillpartiallyseethebackgroundshinethroughit.Thisisgreatformakingexplosions.ThisactionisonlyavailableintheProEdition.

PlaySoundWiththisactionyouplayoneofthesoundresourcesyouaddedtoyourgame.Youcanselectthesoundyouwanttoplayandchoosewhetheritshouldplayonlyonce(thedefault)orloopcontinuously.Multiplewavesoundscanplayatoncebutonlyonemidisoundcanplayatatime.Soifyoustartamidisound,thecurrentmidisoundisstopped.

StopSoundThisactionstopstheindicatedsound.Ifmultipleinstancesofthissoundareplayingallarestopped.

CheckSoundIftheindicatedsoundisplayingthenextactionisperformed.Otherwiseitisskipped.YoucanselectNottoindicatethatthenextactionshouldbeperformediftheindicatedsoundisnotplaying.Forexample,youcancheckwhethersomebackgroundmusicisplayingand,ifnot,startsomenewbackgroundmusic.Notethatthisactionreturnstruewhenthesoundactuallyplaysthroughthespeakers.Afteryoucalltheactiontoplayasounditdoesnotimmediatelyreachthespeakerssotheactionmightstillreturnfalseforawhile.Similar,whenthesoundisstoppedyoustillhearitforawhile(e.g.becauseofecho)andtheactionwillstillreturntrue.

PreviousRoomMovetothepreviousroom.Youcanindicatethetypeoftransitioneffectbetweentherooms.Youshouldexperimenttoseewhatworksbestforyou.Whentheroomsdonothavethesamesizeyoubetterdonotusetransitions.Ifyouareinthefirstroomyougetanerror.

NextRoomMovetothenextroom.Youcanindicatethetransition.

RestartRoomThecurrentroomisrestarted.Youindicatethetransitioneffect.

DifferentRoomWiththisactionyoucangotoaparticularroom.Youindicatetheroomandthetransitioneffect.

CheckPreviousThisactiontestswhetherthepreviousroomexists.Ifso,thenextactionisexecuted.Younormallyneedthistestbeforemovingtothepreviousroom.

CheckNextThisactiontestswhetherthenextroomexists.Ifso,thenextactionisexecuted.Younormallyneedthistestbeforemovingtothenextroom.

Mainactions,set2

Herearesomemoremainactions,dealingwithtiming,givingmessagestotheuser,anddealingwiththegameasawhole.

SetAlarmWiththisactionyoucansetoneofthetwelvealarmclocksfortheinstance.Youselectthenumberofstepsandthealarmclock.Aftertheindicatednumberofsteps,theinstancewillreceivethecorrespondingalarmevent.YoucanalsoincreaseordecreasethevaluebycheckingtheRelativebox.Ifyousetthealarmclocktoavaluelessthanorequalto0youswitchitoff,sotheeventisnotgenerated.

SleepWiththisactionyoucanfreezethesceneforaparticulartime.Thisistypicallyusedatthebeginningorendofalevelorwhenyougivetheplayersomemessage.Youspecifythenumberofmillisecondstosleep.Alsoyoucanindicatewhetherthescreenshouldfirstberedrawntoreflectthemostrecentsituation.

DisplayMessageWiththisactionyoucandisplayamessageinadialogbox.Yousimplytypeinthemessage.Ifyouusea#symbolinthemessagetextitwillbeinterpretedasanewlinecharacter.(Use\#togetthe#symbolitself.)Ifthemessagetextstartswithaquoteordoublequotesymbol,itisinterpretedasanexpression.Seebelowformoreinformationaboutexpressions.

ShowInfoWiththisactionyoupopupthegameinformationwindow.

RestartGameWiththisactionyourestartthegamefromthebeginning.

EndGameWiththisactionyouendthegame.

SaveGameWiththisactionyoucansavethecurrentgamestatus.Youspecifythefilenameforsaving(thefileiscreatedintheworkingdirectoryforthegame).Laterthegamecanbeloadedwiththenextaction.(Pleaserealizethatonlythebasicgamestatusissave.Thingsthatareforexamplenotsavedarethecurrentsoundthatisplaying,andadvancedaspectslikethecontentsofdatastructures,particles,etc.)

LoadGameLoadthegamestatusfromafile.Youspecifythefilename.MakesurethesavedgameisforthesamegameandcreatedwiththesameversionofGameMaker.Otherwiseanerrorwilloccur.(Tobeprecise,thegameisloadedattheendofthecurrentstep.Sosomeactionsafterthisonearestillexecutedinthecurrentgame,nottheloadedone!)

Controlactions

Thereareanumberofactionswithwhichyoucancontrolwhichotheractionsareperformed.Mostoftheseactionsaskaquestion,forexamplewhetherapositionisempty.Whentheanswerisyes(true)thenextactionisexecuted,otherwiseitisskipped.Ifyouwantmultipleactionstobeexecutedorskippedbasedontheoutcomeyoucanputtheminablockbyputtingstartblockandendblockactionsaroundthem.Therecanalsobeanelsepartwhichisexecutedwhentheanswerisno.Soaquestiontypicallylooksasfollows:

Herethequestionisaskedwhetherapositionforthecurrentinstanceiscollisionfree.Ifso,theinstancestartsmovinginagivendirection.Ifnot,theinstancejumpstoagivenposition.Notethattheblocksareindented.Thisgivesabetteroverviewoftheactions.(Inparticularwhenyouuseblocksinsideblocks.)Alsoitiseasiertodetectwhenyouforgotastartblockorendblockaction.

ForallquestionsthereisafieldlabeledNOT.Ifyoucheckthisfield,theresultofthequestionisreversed.Thatis,iftheresultwastrueitbecomesfalseandifitwasfalse,itbecomestrue.Thisallowsyoutoperformcertainactionswhenaquestionisnottrue.

Formanyquestionsyoucanindicatethattheyshouldapplytoallinstancesofaparticularobject.Inthiscasetheresultistrueonlyifitis

trueforallinstancesoftheobject.Forexample,youcancheckwhetherforallballsthepositionslightlytotherightiscollisionfree.

Thefollowingquestionsandrelatedactionsareavailable.(Notethattheyallhaveadifferentlyshapediconandadifferentbackgroundcolorsothattheycanmoreeasilybedistinguishedfromotheractions.)

CheckEmptyThisquestionreturnstrueifthecurrentinstance,placedattheindicatedpositiondoesnotgenerateacollisionwithanobject.Youcanspecifythepositionaseitherabsoluteorrelative.Youcanalsoindicatewhetheronlysolid,orallobjects,shouldbetakenintoaccount.Thisactionistypicallyusedtocheckwhethertheinstancecanmovetoaparticularposition.

CheckCollisionThisisthereverseofthepreviousaction.Itreturnstrueifthereisacollisionwhenthecurrentinstanceisplacedatthegivenposition(again,eitheronlywithsolidobjectsorwithallobjects).

CheckObjectThisquestionreturnstrueiftheinstanceplacedattheindicatepositionmeetsaninstanceoftheindicatedobject.

TestInstanceCountYouspecifyanobjectandanumber.Ifthecurrentnumberofinstancesoftheobjectisequaltothenumberthequestionreturnstrue.Otherwiseitreturnsfalse.Youcanalsoindicatethatthecheckshouldbewhetherthenumberofinstancesissmallerthanthegivenvalueorlargerthanthegivenvalue.Thisistypicallyusedtocheckwhetherallinstancesofaparticulartypearegone.Thisisoftenthemomenttoendaleveloragame.

TestChanceYouspecifythenumberofsidesofadicewhichisthenthrown.Thenifthedicelandsonone,theresultistrueandthenextactionisperformed.Thiscanbeusedtoputanelementofrandomnessinyourgame.Forexample,ineachstepyoucangeneratewithaparticularchanceabomb

orachangeofdirection.Thelargerthenumberofsidesofthedice,thesmallerthechance.Youcanactuallyuserealnumbers.Forexampleifyousetthenumberofsidesto1.5thenextactionisperformedtwooutofthreetimes.Usinganumbersmallerthan1makesnosense.

CheckQuestionYouspecifyaquestion.Adialogisshowntotheplayerwithayesandanobutton.Theresultistrueistheplayeranswersyes.

TestExpressionThisisthemostgeneralquestionaction.Youcanenteranarbitraryexpression.Iftheexpressionevaluatestotrue(thatis,anumberlargerorequalto0.5)thenextactionisperformed.Seebelowformoreinformationonexpressions.

CheckMouseReturnstrueiftheindicatedmousebuttonispressed.Astandarduseisinthestepevent.Youcancheckwhetheramousebuttonispressedand,ifso,forexamplemovetothatposition(usethejumptoapointactionwithvaluesmouse_xandmouse_y).

CheckGridReturnstrueifthepositionoftheinstanceliesonagrid.Youspecifythehorizontalandverticalspacingofthegrid.Thisisveryusefulwhencertainactions,likemakingaturn,areonlyallowedwhentheinstanceisonagridposition.

StartBlockIndicatesthestartofablockofactions.

EndBlockIndicatestheendofablockofactions.

ElseBehindthisactiontheelsepartfollows,thatisexecutedwhentheresultofthequestionisfalse.

RepeatThisactionisusedtorepeatthenextaction(orblockofactions)anumberoftimes.Yousimplyindicatethenumber.

ExitEventWhenthisactionisencounterednofurtheractionsinthiseventareexecuted.Thisistypicallyusedafteraquestion.Forexample,whenapositionisfreenothingneedstobedonesoweexittheevent.Inthisexample,thefollowingactionsareonlyexecutedwhenthereisacollision.

Ifyouwantmorecontroloverwhatishappeninginthegameyoucanusethebuilt-inprogramminglanguagethatisdescribedinPart4ofthedocumentation.Ifgivesyoumuchmoreflexibilitythanusingtheactions.Therearealsoactionstodefineandtestvariables.Theyaresimplertousethancodeandcanbeveryusefulforyourgames.Thefollowingactionsdealwiththis.

ExecuteCodeWhenyouaddthisaction,aformshowsinwhichyoucantypeapieceofcodewhichmustbeexecute.Thiscancontainsimplefunctioncallsormorecomplexcode.Usethecodeactionpreferablyonlyforsmallpiecesofcode.ForlongerpiecesyouarestronglyadvisedtousescriptswhicharedescribedinPart2ofthedocumentation.

CommentUsethisactiontoaddalineofcommenttotheactionlist.Thelineisshowninitalicfont.Addingcommentshelpsyourememberwhatyoureventsaredoing.Theactiondoesnotdoanything.Butrealizethatitstillisanaction.Sowhenyouplaceitafteraconditionalactionitistheactionthatisexecutediftheconditionistrue(eventhoughitdoesnotdoanything).

SetVariableTherearemanybuilt-invariablesinthegame.Withthisactionyoucanchangethese.Alsoyoucancreateyourownvariablesandassignvaluestothem.Youspecifythenameofthevariableandthenewvalue.When

youchecktheRelativebox,thevalueisaddedtothecurrentvalueofthevariable.Pleasenotethatthiscanonlybedoneifthevariablealreadyhasavalueassignedtoit!Seebelowformoreinformationaboutvariables.

TestVariableWiththisactionyoucancheckwhatthevalueofaparticularvariableis.Ifthevalueofthevariableisequaltothenumberprovided,thequestionreturnstrue.Otherwiseitreturnsfalse.Youcanalsoindicatethatthecheckshouldbewhetherthevalueissmallerthanthegivenvalueorlargerthanthegivenvalue.Seebelowformoreinformationaboutvariables.Actually,youcanusethisactionalsotocomparetwoexpressions.

DrawVariableWiththisactionyoucandrawthevalueofavariableataparticularpositiononthescreen.Notethatthiscanonlybeusedinthedraweventofanobject.

Scoreactions

Inmostgamestheplayerwillhaveacertainscore.Alsomanygamesgivetheplayeranumberoflives.Finally,oftentheplayerhasacertainhealth.Thefollowingactionsmakeiteasytodealwiththescore,lives,andhealthoftheplayer.

SetScoreGameMakerhasabuilt-inscoremechanism.Thescoreisnormallydisplayedinthewindowcaption.Youcanusethisactiontochangethescore.Yousimplyprovidethenewvalueforthescore.Oftenyouwanttoaddsomethingtothescore.Inthiscasedon'tforgetthechecktheRelativebox.

TestScoreWiththisquestionactionyoucancheckwhetherthescorehasreachedaparticularvalue.Youindicatethevalueandwhetherthescoreshouldbeequaltothatvalue,besmallerthanthevalueorbelargerthanthevalue.

DrawScoreWiththisactionyoucandrawthevalueofthescoreataparticularpositiononthescreen.Youprovidethepositionsandthecaptionthatmustbeplacedinfrontofthescore.Thescoreisdrawninthecurrentfont.Thisactioncanonlybeusedinthedrawingeventofanobject.

ShowHighscoreForeachgamethetoptenscoresaremaintained.Thisactiondisplaysthehighscorelist.Ifthecurrentscoreisamongthetopten,thenewscoreisinsertedandtheplayercantypehisorhername.Youcanindicatewhatbackgroundimagetouse,whetherthewindowshouldhaveaborder,whatthecolorforthenewentryandtheotherentriesmustbe,andwhichfonttouse.

ClearHighscoreThisactionclearsthehighscoretable.

SetLivesGameMakeralsohasabuilt-inlivessystem.Withthisactionyoucanchangethenumberoflivesleft.Normallyyousetittosomevaluelike3atthebeginningofthegameandthendecreaseorincreasethenumberdependingonwhathappens.Don'tforgettochecktheRelativeboxifyouwanttoaddorsubtractfromthenumberoflives.Atthemomentthenumberoflivesbecomes0(orsmallerthan0)a"nomorelives"eventisgenerated.

TestLivesWiththisquestionactionyoucancheckwhetherthenumberofliveshasreachedaparticularvalue.Youindicatethevalueandwhetherthenumberoflivesshouldbeequaltothatvalue,besmallerthanthevalueorbelargerthanthevalue.

DrawLivesWiththisactionyoucandrawthenumberoflivesataparticularpositiononthescreen.Youprovidethepositionsandthecaptionthatmustbeplacedinfrontofthenumberoflives.Thenumberoflivesisdrawninthecurrentfont.Thisactioncanonlybeusedinthedrawingeventofanobject.

DrawLifeImagesRatherthandrawingthenumberoflivesleftasanumber,itisoftennicertouseanumberofsmallimagesforthis.Thisactiondoespreciselythat.Youspecifythepositionandtheimageandattheindicatedpositionthenumberoflivesisdrawnasimages.Thisactioncanonlybeusedinthedrawingeventofanobject.

SetHealthGameMakerhasabuilt-inhealthmechanism.Youcanusethisactiontochangethehealth.Avalueof100isconsideredfullhealthand0isnohealthatall.Yousimplyprovidethenewvalueforthehealth.Oftenyouwanttosubtractsomethingfromthehealth.Inthiscasedon'tforgetthechecktheRelativebox.Whenthehealthbecomessmallerorequalto0anoutofhealtheventisgenerated.

TestHealthWiththisquestionactionyoucancheckwhetherthehealthhasreachedaparticularvalue.Youindicatethevalueandwhetherthehealthshouldbeequaltothatvalue,besmallerthanthevalueorbelargerthanthevalue.

DrawHealthWiththisactionyoucandrawthehealthintheformofahealthbar.Whenthehealthis100thefullbarisdrawn.Whenitis0thebarisempty.Youindicatethepositionandsizeofthehealthbarandthecolorofthebarandthebackground.

ScoreCaptionNormallyinthewindowcaptionthenameoftheroomandthescoreisdisplayed.Withthisactionyoucanchangethis.Youcanindicatewhetherornottoshowthescore,lives,and/orhealthandwhatthecaptionforeachofthesemustbe.

Drawactions

Normallyineachstepofthegame,foreachinstance,itsspriteisdrawnintheroom.Youcanchangethisbyputtingactionsinthedrawevent.(Notethattheseareonlyexecutedwhentheinstanceisvisible!)Thefollowingdrawingactionsareavailable.Theseactionsonlymakesenseinthedrawingevent.Atotherplacestheyarebasicallyignored.

DrawSpriteYouspecifythesprite,theposition(eitherabsoluteorrelativetothecurrentinstanceposition)andthesubimageofthesprite.(Thesubimagesarenumberedfrom0upwards.)Ifyouwanttodrawthecurrentsubimage,usenumber-1.

DrawBackgroundYouindicatethebackgroundimage,theposition(absoluteorrelative)andwhethertheimageshouldbetiledallovertheroomornot.

DrawTextYouspecifythetextandtheposition.A#symbolinthetextisinterpretedasgoingtoanewline.(Use\#togetthe#symbolitself.)Soyoucancreatemulti-linetexts.Ifthetextstartswithaquoteoradoublequote,itisinterpretedasanexpression.Forexample,youcanuse

'X:'+string(x)

todisplaythevalueofthex-coordinateoftheinstance.(Thevariablexstoresthecurrentx-coordinate.Thefunctionstring()turnsthisnumberintoastring.+concatenatesthetwostrings.)

DrawScaledTextThisactionissimilartothepreviousactionbutthistimeyoucanalsospecifyahorizontalandverticalscalingfactortochangethesizeofthetextandyoucanspecifyanangletorotateit.ThisactionisonlyavailableintheProEdition.

DrawRectangleYouspecifythecoordinatesofthetwooppositecornersoftherectangle;eitherabsoluteorrelativetothecurrentinstanceposition.

HorizontalGradientThisactionalsodrawsarectanglebutthistimeusingagradientcolorthatchangesfromlefttoright.Youspecifytherectangleandthetwocolorstouse.ThisactionisonlyavailableintheProEdition.

VerticalGradientThisactionalsodrawsarectanglebutthistimeusingagradientcolorthatchangesfromtoptobottom.Youspecifytherectangleandthetwocolorstouse.ThisactionisonlyavailableintheProEdition.

DrawEllipseThisactiondrawsanellipse.Youspecifythecoordinatesofthetwooppositecornersofthesurroundingrectangle;eitherabsoluteorrelativetothecurrentinstanceposition.

GradientEllipseAgainanellipseisdrawnbutthistimeyouspecifyacolorforthecenterandtheboundary.ThisactionisonlyavailableintheProEdition.

DrawLineYouspecifythecoordinatesofthetwoendpointsoftheline;eitherabsoluteorrelativetothecurrentinstanceposition.

DrawArrowDrawsanarrow.Youspecifythecoordinatesofthetwoendpointsofthelineandthesizeofthearrowtip.

SetColorLetsyousetthecolorusedfordrawingshapes,lines,andtext.(Itdoesnotinfluencethewayspritesandbackgroundsaredrawn.)

SetFullScreen

Withthisactionyoucanchangethescreenmodefromwindowedtofullscreenandback.Youcanindicatewhethertotogglethemodeorwhethertogotowindowedorfullscreenmode.

TakeSnapshotWiththisactionyoucantakeasnapshotimageofthegameandstoreitina.pngfile.Youspecifythefilenametostoretheimagein.ThisactionisonlyavailableintheProEdition.

CreateEffectWiththisactionyoucancreateallsortsofeffectsinaverysimpleway.Youspecifythetypeofeffect,e.g.anexplosionorsmoke,itsposition,itssizeanditscolorandwhetheritshouldbeshownbelowtheobjectsorontopofthem.Fortherestitworksautomatic.(Forrainandsnowthepositionisirrelevantasitalwaysfallsdownfromthetopofthescreen.Togetcontinuousrainyoushouldcreateitineachstep.)Pleasenotethatbelowactuallymeansatadepthof100000andabovemeansatadepthof-100000.ThisactionisonlyavailableintheProEdition.

Usingexpressionsandvariables

Inmanyactionsyouneedtoprovidevaluesforparameters.Ratherthanjusttypinganumber,youcanalsotypeaformula,e.g.32*12.Butyoucanactuallytypemuchmorecomplicatedexpressions.Forexample,ifyouwanttodoublethehorizontalspeed,youcouldsetitto2*hspeed.Herehspeedisavariableindicatingthecurrenthorizontalspeedoftheinstance.Therearealargenumberofothervariablesthatyoucanuse.Someofthemostimportantonesare:

xthex-coordinateoftheinstanceythey-coordinateoftheinstancehspeedthehorizontalspeed(inpixelsperstep)vspeedtheverticalspeed(inpixelsperstep)directionthecurrentdirectionofmotionindegrees(0-360)speedthecurrentspeedinthisdirectionvisiblewhethertheobjectisvisible(1)orinvisible(0)image_indexthisvariableindicatewhichsubimageinthecurrentspriteiscurrentlyshown.Ifyouchangeitandsetthespeedto0(seebelow)youcandisplayafixedsubimage.image_speedthisvariableindicatesthespeedwithwhichthesubimagesareshown.Thedefaultvalueis1.Ifyoumakethisvaluelargerthan1somesubimagesareskippedtomaketheanimationfaster.Ifyoumakeitsmallerthan1theanimationbecomesslowerbyrepeatingsubimages.scorethecurrentvalueofthescorelivesthecurrentnumberofliveshealththecurrenthealth(0-100)mouse_xx-positionofthemousemouse_yy-positionofthemouse

Youcanchangemostofthesevariablesusingthesetvariableaction.Youcanalsodefineyourownvariablesbysettingthemtoavalue.(Don'tuserelative,becausetheydon'texistyet.)Thenyoucanusethesevariablesinexpressions.Variablesyoucreatearelocaltothecurrent

instance.Thatis,eachobjecthasitsowncopyofthem.Tocreateaglobalvariable,putthewordglobalandadotinfrontofit.

Youcanalsorefertothevaluesofvariablesforotherobjectsbyputtingtheobjectnameandadotinfrontofthem.Soforexample,ifyouwantaballtomovetotheplacewherethecoinisyoucansetthepositionto(coin.x,coin.y).Inthecaseofacollisioneventyoucanrefertothex-coordinateoftheotherobjectasother.x.Inconditionalexpressionsyoucanusecomparisonslike<(smallerthan),>,etc.

Inyourexpressionsyoucanalsousefunctions.Forexample,thefunctionrandom(10)givesarandomintegernumberbelow10.Soyoucansetforexamplethespeedordirectionofmotiontoarandomvalue.Manymorefunctionsexist.TheyaredescribedinPart4ofthedocumentation.

Creatingrooms

Nowthatyouhavedefinedtheobjectswiththeirbehaviorintheformofeventsandactions,itistimetocreatetheroomsorlevelsinwhichthegametakesplace.Anygamewillneedatleastoneroom.Intheseroomsweplaceinstancesoftheobjects.Oncethegamestartsthefirstroomisshownandtheinstancesinitcometolifebecauseoftheactionsintheircreationevents.

Therearealargenumberofpossibilitieswhencreatingrooms.Besidessettinganumberofpropertiesandaddingtheinstancesoftheobjectsyoucanaddbackgrounds,defineviews,andaddtiles.Mostoftheseoptionsarediscussedlater.Inthischapterwewillonlydiscusssomebasicsettings,theadditionofinstancesofobjects,andthesettingofbackgroundimages.

Tocreatearoom,chooseCreateRoomfromtheResourcesmenu.Thefollowingformwillappear:

Atthetopoftheformthereisatoolbar.Onthisyoucanindicatethesize

ofthegridcellsusedforaligningobjects.Alsoyoucanindicatewhetherornottoshowthegridlinesandwhetherornottoshowthebackgrounds,etc.Itissometimesusefultotemporarilyhidecertainaspectsoftheroom.Realizethoughthatwhenyouareaddinginstancesofobjects,thesewillalwaysbeshown,independentoftheviewsetting.)Therearealsobuttonstoclearallinstancesfromtheroomandtoshiftallinstancesoveranumberofpixels.Usenegativenumberstoshiftthemleftorup.Thisisusefulwhenforinstanceyoudecidedtoenlargetheroom.(Youcanalsousethistoplaceinstancesoutsidetheroom,whichissometimesuseful.).FinallythereistheUndobuttontoundothelastchangetotheroomandtheOKbuttontosavethechanges.(Clickonthecrossatthetoprighttoclosetheformwithoutsavingthechanges.)

Attheleftyouwillseethreetabpages(fiveinadvancedmode).Theobjectstabiswhereyouaddinstancesofobjectstotheroom.Inthesettingstabyoucanindicateanumberofsettingsfortheroom.Inthebackgroundstabyoucansetbackgroundimagesfortheroom.

Addinginstances

Attherightintheroomdesignformyouseetheroom.Atthestartitisempty,withagraybackground.

Toaddinstancestotheroom,firstselecttheobjectstabifthisoneisnotalreadyvisible.Nextselecttheobjectyouwanttoaddbyclickingonthebuttonwiththemenuicon(orbyclickingintheimageareaattheleft).Theimageoftheobjectappearsattheleft.(Notethatwhenyouchangedtheoriginofthespritethereisacrossintheimage.Thisindicateshowtheinstanceswillbealignedwiththegrid.)Nowclickwithyourleftmousebuttonintheroomareaattheright.Aninstanceoftheobjectappears.Itwillsnaptotheindicatedgrid.Ifyouholdthe<Alt>keywhileplacingtheinstanceitisnotalignedtothegrid.Ifyouholddownthemousebuttonwhiledraggingitovertheroom,youmovetheinstancetothecorrectplace.Ifyouholdthe<Shift>keywhilepressingandmovingthemousemultipleinstancesareadded.Withtherightmousebuttonyoucanremoveinstances.Inthiswayyoudefinethecontentsoftheroom.

Asyouwillnotice,ifyouplaceaninstanceontopofanotherone,theoriginalinstancedisappears.Normallythisiswhatyouwant,butnotalways.ThiscanbeavoidedbyuncheckingtheboxlabeledDeleteunderlyingattheleft.

Ifyouwanttochangethepositionofaninstance,holdthe<Ctrl>keyandclickwiththeleftmousebuttonontheinstanceandholddownthebutton.Youcannowdragittoanewposition.(Use<Alt>forprecisepositioning.)

Ifyouholdthe<Ctrl>keywhileclickingwiththerightmousebuttononaninstance,amenuappears.Hereyoucandeletetheobject,typeinaprecisepositionfortheinstance,ormovethebottommostinstanceatthepositiontothetoporsendthetopmostinstancetothebottom.

Roomsetting

Eachroomhasanumberofsettingsthatyoucanchangebyclickingonthesettingstab.

Eachroomhasaname.Bestgiveitameaningfulname.Therealsoisacaption.Thiscaptionisdisplayedinthewindowcaptionwhenthegameisrunning.Youcansetthewidthandheightoftheroom(inpixels).Alsoyoucansetthespeedofthegame.Thisisthenumberofstepspersecond.Thehigherthespeed,thesmootherthemotionis.Butyouwillneedafastercomputertorunit.

Settingthebackground

Withthetabbackgroundsyoucansetthebackgroundimagefortheroom.Actually,youcanspecifymultiplebackgrounds.Thetabpagelooksasfollows:

Atthetopyouwillseethebackgroundcolor.Youcanclickonittochangeit.Thebackgroundcolorisonlyusefulifyoudon'tuseabackgroundimagethatcoversthewholeroom.Otherwise,bestunchecktheboxlabeledDrawbackgroundcolorbecausethiswillbeawasteoftime.

Atthetopyouseealistof8backgrounds.Youcandefineeachofthembutmostofthetimeyouwillneedjustoneortwo.Todefineabackground,firstselectitinthelist.NextchecktheboxlabeledVisiblewhenroomstartsotherwiseyouwon'tseeit.Thenameofthebackgroundwillbecomeboldwhenitisdefined.Nowindicateabackgroundimageinthemenu.Thereareanumberofsettingsyoucanchange.Firstofallyoucanindicatewhetherthebackgroundimageshouldtiletheroomhorizontallyand/orvertically.Youcanalsoindicatethepositionofthebackgroundintheroom(thiswillalsoinfluencethetiling).Adifferentoptionistostretchthebackground.Thebackgroundwillthenbescaledsothatitfillstheentireroom.Theaspectrationoftheimagewillnotbemaintained.Finallyyoucanmakethebackgroundscrollingbygivingitahorizontalorverticalspeed(pixelsperstep).Betternotusescrollingwithastretchedbackground.Theresultwillbeabitjaggy.

ThereisonemorecheckboxlabeledForegroundimage.Whenyoucheckthisbox,thebackgroundisactuallyaforeground,whichisdrawnontopofeverythingelseratherthanbehindit.Clearlysuchanimage

shouldbepartiallytransparenttobeofanyuse.

Distributingyourgame

Withtheinformationintheprecedingchaptersyoucancreateyourgames.Whenyourgameisfinishedyouobviouslywantotherpeopletoplayit.Youcanofcoursegivethemthe.gmkfilethatyoucreatedandletthemuseGameMakertoplayitbutthisisnormallynotwhatyouwant.Firstofall,youdon'twantotherstobeabletochangethegame,andsecondlyyoualsowantpeopletoplaythegameeveniftheydonothaveGameMaker.Soyouwouldliketocreateastand-aloneexecutableofyourgame.

Creatingstand-aloneexecutablesisveryeasyinGameMaker.IntheFilemenuyouselecttheitemCreateExecutable.Youwillbeaskedforthenameoftheexecutablethatshouldcontainthegame.Indicateaname,pressOKandyouhaveyourstand-alonegamethatyoucangivetoanyoneyoulike.Youcanchangetheiconforthestand-alonegameintheGlobalGameSettings.SeePart3fordetails.

Onceyouhavecreatedastand-aloneexecutableinthewaydescribedaboveyoucangivethisfiletootherpeopleorplaceitonyourwebsitetodownload.YouarefreetodistributethegamesyoucreatewithGameMakerinanywayyoulike.Youcanevensellthem.Thisofcourseassumesthatthesprites,images,andsoundsyouusecanbedistributedorsoldaswell.Seetheenclosedlicenseagreementformoreinformation.

Itisnormallyusefultozipyourexecutable,togetherwithsomereadmeinformation.InWindowsXPandlaterthiscanbedonedirectlythroughtherightmousebuttonmenu,andtherearemanyfreeziputilitiesavailableontheweb.Alternativelyyoucancreateaninstallerforyourgame.Again,alargenumberoffreeinstallationcreationprogramsareavailableontheweb.

IfyouwantyourgametobeplayedbymanymorepeoplewerecommendyoutouploadittotheYoYoGameswebsiteandpresson


theSharebuttonatthetop.

Advanceduse

ThissectionofthehelpfilegivesyouinformationaboutthemoreadvancedaspectsofGameMaker.

InformationontheadvanceduseofGameMakercanbefoundinthefollowingpages:

AdvancedUserInterfaceMoreaboutSpritesMoreaboutSoundsandMusicMoreaboutBackgroundsMoreaboutObjectsMoreActionsConstantsTriggerEventsIncludingFilesMoreaboutRoomsFontsPathsTimeLinesScriptsExtensionPackagesExportingandImportingResources

Advancedmode

UptonowwehaveonlyconsideredthesimplefeaturesofGameMaker.Buttherearealotmorepossibilities.TobeabletousetheseyoumustrunGameMakerinadvancedmode.Thisiseasytochange.IntheFilemenu,clickonthemenuitemAdvancedmode.(TofullyseetheeffectsyoushouldrestartGameMakeroratleastsaveyourgameandloaditanew.)

WhenyoustartGameMakerinadvancedmode,thefollowingformisshown:

Itcontainsallthatwasthereinsimplemode,butthereareanumberofadditionalresources,buttons,andmenuitems.Also,aswewillseeinthechaptersthatfollow,thedifferentresourceshaveadditionaloptions.Herewewilldiscusstheadditionalmenuitems.

Filemenu

Inthefilemenuyoucanfindthefollowingadditionalcommands:

PublishyourGame.Thiscommandwilltakeyoutoourwebsitewereyoucaneasilyuploadandpublishyourfinishedgamesuchthateverybodycanplayit.Carefullyfollowtheinstructionstomakeyourgameavailable.Pleaseonlyusethisforfinishedgames,notforpreliminaryversions.ThispossibilityisonlyavailableintheProEdition.ImportResources.Withthiscommandyoucanimportresourcesthatyouexportedwiththenextcommand.SeethesectiononExportingandImportingResourcesformoredetails.ExportResources.Withthiscommandyoucanexportresourcestoafile.SeethesectiononExportingandImportingResourcesformoredetails.Preferences.HereyoucansetanumberofpreferencesaboutGameMaker.TheywillberememberedbetweendifferentcallsofGameMaker.FormoreinformationseethepageonPreferences.

Editmenu

Intheeditmenuyoucanfindthefollowingadditionalcommands:

Addgroup.Resourcescanbegroupedtogether.Thisisveryusefulwhenyoumakelargegames.Forexample,youcanputallsoundsrelatedtoacertainobjectinagroup,oryoucangroupallobjectsthatareusedinaparticularlevel.Thiscommandcreatesanewgroupinthecurrentlyselectedresourcetype.Youwillbeaskedforaname.Groupscanagaincontaingroups,etc.Youcandragresourcesintothegroups.FindResource.Withthiscommandyoutypeinthenameofaresourceanditopenthecorrespondingpropertyform.ExpandResourceTree.Fullyexpandstheresourcetree,showingallresources.CollapseResourceTree.Fullycollapsestheresourcetree,hidingallresources.ShowObjectInformation.Usingthiscommandyoucangetanoverviewofallobjectsinthegame.

Resourcesmenu

Inthismenuyoucannowalsocreatetheadditionalresources.Notethatforeachofthemthereisalsoabuttononthetoolbarandakeyboardshortcut.Therearethreespecialmenuitemsatthebottom:

DefineConstants.Hereyoucandefineconstantsforuseinyourscriptsandactionarguments.FormoreinformationseethesectiononConstants.DefineTriggers.Hereyoucandefineyourowntriggerevents.FormoreinformationseethesectiononTriggerEvents.IncludedFiles.Hereyoucanindicatewhichadditionalfilesshouldbeincludedinthegameexecutable.FormoreinformationseethesectiononIncludingFiles.

Scriptsmenu

Inthescriptsmenuyoucanfindthefollowingadditionalcommands:

ImportScripts.Canbeusedtoimportusefulscriptsfromfiles.ExportScripts.Canbeusedtosaveyourscriptsinafile,tobeusedbyothers.Whenyouselectascriptresourceonlythisscriptissaved.Whenyouselectagroupallscriptsinthegrouparesaved.Whenyouselecttherootresource(oradifferenttypeofresource)allscriptsaresaved.Thismenuitemisalsoavailablewhenright-clickingonascriptorgroupofscripts.ShowBuilt-inVariables.Showsasortedlistofallbuilt-invariables,bothlocalandglobal.ShowBuilt-inFunctions.Showsasortedlistofallbuilt-infunctions.ShowExtensionFunctions.Showsasortedlistofallfunctionsavailableintheextensionpackagesyouincludedinyourgame.ShowConstants.Showsasortedlistofallbuilt-inconstantsandconstantsdefinedinthegameoptions.ShowResourceNames.Showsasortedlistofallresourcenames.Youcanclickonanametoopentheparticularresourceforediting.

SearchinScripts.Youcansearchforastringinallscripts.Youcanclickononeofthereportedplacestomovethereforediting.CheckResourceNames.Doesacheckofallresourcenames.Nameswillbereportediftheyarenotcorrect,ifthereareduplicateresourcenames,orwhenaresourcenameisthenameofavariable,function,orconstant.Youcanclickonanametoopentheparticularresourceforediting.CheckAllScripts.Checksallscriptsforerrors.Youcanclickononeofthereportedplacestomovethereforediting.

Helpmenu

Hereyoucannowalsofindhelpinformationabouttheextensionpackagesyouareusing.

Preferences

UnderthePreferencesmenuitemintheFilemenuyoucansetanumberofpreferencesthatwillbemaintainedbetweenrunsofGameMaker.Thefollowingpreferencescanbeset:

Generaltab

Showrecentlyeditedgamesinthefilemenu.Ifcheckedtheeightmostrecentlyeditedgamesareshownundertherecentfilesinthefilemenu.Loadlastopenedfileonstartup.IfcheckedwhenyoustartGameMakerthemostrecentlyopenedfileisopenedautomatically.Keepbackupcopiesoffiles.Ifcheckedtheprogramsavesabackupcopyofyourgamewiththeextensiongb0-gb9.YoucanopenthesegamesinGameMaker.Youarestronglyadvisedtouseatleastonebackupcopyforyourwork!Maximumnumberofbackups.Hereyoucanindicatehowmany(1-9)differentbackupcopiesshouldberememberedbytheprogram.Showprogresswhileloadingandsavingfiles.Ifchecked,whenloadorsaveafileaprogressindicatorisshown.

Atstartupcheckfor,andremoveoldtemporaryfiles.GameMakerandgamescreatedwithit,createtemporaryfiles.Normallytheseareautomaticallyremovedbutsometimes,forexamplewhengamescrash,theyareleftbehind.Ifthisoptionischecked,GameMakercheckswhethersuchfilesexistandremovesthematstartup.Don'tshowthewebsiteinthemainwindow.Whencheckedtheimageandlinktothewebsiteonthemainwindowarenotshown.Hidethedesignerandwaitwhilethegameisrunning.Whencheckedthegamemakingprogramishiddenwhileyouaretestingagame.Rungamesinsecuremode.Ifchecked,anygamecreatedwithGameMakerthatrunsonyourmachinewillnotbeallowedtoexecuteexternalprogramsorchangeordeletefilesataplacedifferentfromthegamelocation.(ThisisasafeguardagainstTrojanhorsesalthoughsuccessisnotguaranteed.)Checkingthismeansthatgamesthatutilizesexternalfilesetc.won'tberunningcorrectly.ThesettingonlyworkswhileGameMakerisrunning.SoifyourunthegameindependentlyofGameMaker,forexampleasanexecutablestand-alone,itisNOTruninsecuremode.Shownewsonstartup.WhethertoshowtheGameMakernewsonceadaywhentheprogramisstarted.(CannotbechangedintheLiteEdition.)Shownewsindefaultbrower.WhethertoshowtheGameMakernewsinyourdefaultInternetbrowser,ratherthanintheprogramitself.(CannotbechangedintheLiteEdition.)

Formstab

Showtheorigininthespriteimage.Ifchecked,inthespritepropertiesform,inthespriteimage,theoriginforthespriteisindicated.Inobjectproperties,showhintsforactions.Ifchecked,intheobjectpropertiesform,whenyouholdyourmouseoveroneoftheactions,adescriptionisshown.Whenclosing,removeinstancesoutsidetheroom.Ifchecked,theprogramwarnsyouwhenthereareinstancesortilesoutsidearoomandletsyouremovethem.Rememberroomsettingswhenclosingtheform.Ifchecked,anumberofroomsettings,likewhethertoshowthegrid,whethertodeleteunderlyingobjects,etc.arerememberedwhenyoueditthesameroomlater.

Scriptsandcodetab

Thesesettingsrelatetothebuilt-inscriptandcodeeditor.MostofthesesettingsareexplainedindetailinthepageonScripts.Herewejustgiveashortoverview:

GroupundooperationsWhengroupedmultipleactions(liketypingawholeline)becomesoneoperationforundo.NumberofundoYoucanchangethisnumberbutingeneralthisshouldbefine.AutomaticindentationWhensetEnterandBackspacekeyscleverlydealwithindents.IndentamountHowmuchtoindentwitheachtab.SmarttabsWhensettabsgotothepositionbelowthefirstnon-emptyspaceinthepreviousline.AllowcursorbeyondendoflineWhencheckedyoucanplacethecursoratanypositionintheeditorscreen,alsobeyondtheendofline.Ifuncheckedthisisnotpossible.Thisalsochangesthebehavioroftheleftandrightarrowkeys.Showauto-completionoptionsWhensethelpisgivenonwhichfunctionsandvariablesstartwiththelettersyouaretyping.Dealy(msec)Thedelayinmillisecondsbeforethehelpisshown.Sete.g.to0forimmediate.ShowfunctionargumenthelpWhenset,whentypingfunctionarguments,inthestatusbarhelpaboutthisisprovided.ShowfindstringWhenset,whenevertypinginafindstring,alllocationsareshowninthecode.

ShowlinenumbersWhethertheeditorshoulddisplaythelinenumbers.ShowmatchingbracketsWhethertheeditorshouldindicatematchingopenenclosebrackets.ShowcodesnippetswithF2Whenset,pressingF2willbringupanumberofusefulcodesnippets.CheckcodewhiletypingWhensetthecodeisconstantlycheckedanderrorsreported.UsecolorcodingWhethertousecolorcodingintheeditor.ColorsHereyoucansetthecolorsusedforcolorcoding.Youcanalsoresetthedefaultcolors.FontHereyoucanselectthefontfortheeditor.Notethatonlyfixedpitchfontsareshown.Alsonotethatonlythefontandthesizeareused.

Editors

Hereyoucanchoosewhethertousethebuilt-incodeeditor(highlyrecommended)oranexternaleditor.Inthecaseofanexternaleditor,thescripttextissavedasa.txtfileandtheeditoriscalledwiththisfileasanargument.AftereditingityoushouldsavethefileandclosetheeditorsuchthatGameMakercanreadthefilebackin.

Alsoyoucanchoosewhethertousethebuilt-inimageeditor(highly

recommended)oranexternaleditor.Inthecaseofanexternaleditor,theimageissavedasa.pngfileandtheeditoriscalledwiththisfileasanargument.AftereditingityoushouldsavethefileandclosetheeditorsuchthatGameMakercanreadthefilebackin.

Finallyyoucanindicatethedifferentexternaleditorsforthesoundfilesyouwanttouse.GameMakerdoesnotcontaininternalsoundeditors.Therearethreepossibleeditorshandling.wav,.midand.mp3files.Inthecaseofanexternaleditor,thesoundissavedasa.wav,.mid,or.mp3fileandthecorrespondingeditoriscalledwiththisfileasanargument.AftereditingityoushouldsavethefileandclosetheeditorsuchthatGameMakercanreadthefilebackin.

OtherSettings

ItisalsopossibletochangethelocationofthetempfilesthatGameMakercreatestoe.g.storethegamethatistested.ThislocationcannotbechangedfromthePreferencesbutischangesbycreatingafiletempdir.txtinthefolderwhereGameMakerislocated.Inthisfilethereshouldbeonelinecontainingthelocationofthefolderinwhichthetempfilesarecreates,forexampleC:\GMTEMP.Notethatthenamemustincludethecompletepathandshouldnotendwithabackslash.EachtimeGameMakerisrunauniquetemporaryfolderiscreatedwithinthislocation.Sothingswillworkoutfine,evenwhenmultipleinstancesofGameMakerusethesamelocation.(Notethatthegamesthemselvesalsocreateatempfolderfortheirfiles.Again,thiscanbechangedbycreatingafiletempdir.txtandplacingitinthefolderwherethegameexecutableislocated.)

Secondly,itispossibletochangetheimageGameMakerisusingforthebackgroundofitsmainform.Tothisendplaceanimagefileback.bmpinthefolderwhereGameMakerislocated.

Moreaboutsprites

WhenrunningGameMakerinadvancedmodetheAnumberofadvancedoptionsexist.Whenyouopenthespriteformitwilllookasfollows:

AnewbuttonSaveSpritehasappeared.Withthisbuttonyoucansavethespriteinaproprietaryformat.Thisformatwillnotonlystoretheimage(s)ofthespritebutalsoothersettings,suchascollisionsettingsandtheorigin.Thefilewillhavetheextension.gmspr.GameMakercanloadsuchfilesbutalsothegamescanloadthem.

Atthebottom-left,youcanindicatetheoriginofthesprite.Thisisthepointinthespritethatcorrespondswithitspositionintheroom.Whenyousetaninstanceataparticularposition,theoriginofthespriteisplacedthere.Defaultitisthetopleftcornerofthespritebutitissometimesmoreconvenienttousethecenter(byclickingtheCenterbutton)orsomeotherimportantpoint.Youcanevenchooseanoriginoutsidethesprite.Youcanalsosettheoriginbyclickinginthespriteimage.Theoriginwillbeshownwithacross.

Mostimportantaretheoptionsrelatedtocollisionchecking.Whenevertwoinstancesmeetacollisioneventisgenerated.Collisionsarecheckedinthefollowingway.Eachspritehasamask.Defaultthiscorrespondsto

allpixelsthatarenotfullytransparent.Whentwopixelsinthemasksofthetwospritesoverlap,acollisionisreported.

Sometimesyoudon'twantprecisecollisionchecking.Inthiscase,unchecktheboxPrecisecollisionchecking.Nowtheboundingboxisusedasthemask.

Whenthespriteshasmultiplesubimages,defaultthereisjustasinglemaskthatcombinesthemasksofallsubimages.Normallythisiswhatyouwantbutincertainsituationsyoumightwanteachsubimagetohaveitsownmask.InthiscasechecktheboxSeparatecollisionmasks.

CollisionMasks

Ifyouwantevenmorecontroloverthecollisionmasks,pressthebuttonModifyMask.Thefollowingwindowwillshow:

Atthelefttopthereisagaintheinformationaboutthespriteimage.Youcanshowthedifferentsubimages.Alsoyoucanindicateherewhethertoshowthecollisionmask(defaulton).Inthiscase,intheimagesattherightthemaskisshownindark.Youcanalsozoominandouttogetabetterview.

Totherightofthisyoucanchangetheboundingbox.Onlypixelsinsidethisboundingboxareusedforthemask.Defaulttheboundingboxis

automaticallycomputed,takingthealphatoleranceintoaccount,separateforeachsubimage,whenusingseparatecollisionmasks.Youcanalsosetittothefullimageoryoucansetittomanual.Inthelattercaseyoucanspecifytheboundingboxyourself.Whensettomanualyoucanalsodrawtheboundingboxwiththeleftmousebuttonintheimage,oryoucanmoveitwiththerightmousebutton.(Notethoughthatthemaskisshownwhiledrawing,nottheboundingbox!)

Belowthisyoucanindicatetheshapeofthemask.Defaultisprecise,pixel-wisecollisionchecking,butyoucanselectherealsotousetheboundingrectangle,adisk(orellipse)insideit,oradiamondshape.Rectanglesordisksareismanycasesbetterrepresentationsoftheshape.(Notethatthechoicehasnoeffectonspeed!)

Finally,attheleftbottomyoucan(again)indicatewhetherornotthereshouldbeseparatecollisionmasksforallsubimages.(Notethatifyousettheboundingboxmanual,asingleboundingboxwillbeusedforallsubimages,regardlessofthissetting.)Youcanalsoindicatethetolerancewithrespecttothetransparency.Withahighertolerancealsopixelsthatarepartiallytransparentareleftoutsidethemask.Thisinfluencesboththeboundingbox(whennotsettomanual)andthemaskforprecisecollisionchecking.

Itisimportanttocarefullydecideonthecollisionmaskyouuseforyoursprites.Althoughprecisecollisioncheckingmightseemthemostlogicaloption,inmanycasesgameplayisimprovedbyusingboundingboxesordisks,ormasksthatareabitsmallerthantheactualsprites.Ifyouwantevenfurthercontroloverthemask,notethatforobjectsyoucanspecifyadifferentspritetouseasmask.Inthiswayyoucanmakethecollisionmaskcompletelyindependentoftheimage.

Onceyouaredone,pressOK.Ifthemaskwasmodified,thewordModifiedwillshowinthespriteformsuchthatyouareremindedthatyouchangedsomesettingshere.

EditingSprites

GameMakerhasextensivepossibilitiestocreateandchangeyourownsprites.Informationaboutthiscanbefoundinthefollowingpages:

EditingyourspritesStripsEditingindividualsubimages

Editingyoursprites

Uptonowweloadedourspritesfromfiles.ItisthoughalsopossibletocreateandinparticularmodifythemwithinGameMaker.Todothis,openthespritepropertywindowbydoubleclickingononeofyoursprites(orbycreatinganewone).NowpressthebuttonlabeledEditSprite.Anewformwillappearshowingallthesubimagesthatmakeupthesprite.

Thespriteeditorformwilllookasfollows:

Attherightyouseethedifferentimagesthatmakeupthesprite.NotethatinGameMakerallsubimagesofaspritemusthavethesamesize.Attheleftananimationofthespriteplays.(Ifyoudon'tseetheanimation,checktheboxlabeledShowPreview.)Belowthepreviewyoucanchangethespeedoftheanimationandthebackgroundcolor.Alsoyoucanselectoneofthebackgroundsinyourgameandwhetheritmustbestreched.Inthiswayyoucangetanideaofwhattheanimationwilllooklikeinthegame.(Notethatthisspeedisonlyforpreview.Thespeedoftheanimationduringthegamedependsontheroomspeed.)

Thespriteeditorcontainsmanycommandstocreateandchangethesprite.Theseareallgiventhroughthemenus.(Forsometherearebuttonsonthetoolbar.)Somecommandsworkonindividualimages.Theyrequirethatyoufirstselectasubimagewiththemouse.

Filemenu

Thefilemenucontainsanumberofcommandsrelatedtoloadingandsavingsprites.

New.Createsanew,emptysprite.Youmustindicatethesizeofthesprite.(Remember,allimagesinaspritemusthavethesamesize.)CreatefromFile.Createsthespritefromafile.Manyfiletypescanbeused.Theyallcreateaspriteconsistingofasingleimage,exceptforanimatedGIFfilesthataresplitintothesubimagesandstripsthathaveannameendingwith_stripXX.Whenselectingafileyoucanindicatewhethertheimageshouldbeopaque,whethertoremovethebackground,andwhethertosmooththeedge.Youcanselectmultipleimageswhichwillthenallbeloaded.Theyshouldpreferablyhavethesamesize,otherwise,theircanvassizeswillbeadapted.AddfromFile.Addsanimage(ormultipleimages)fromafiletothecurrentsprite.Iftheimagesdonothavethesamesizeyoucanchoosewheretoplacethemortostretchthem.Youcanselectmultipleimageswhichwillthenallbeloaded.Theymustpreferablyhavethesamesize.SaveasPNGFile.SavesthespriteasastripinaPNGfile.Whenthespritehasmultiplesubimagesthetext_stripXXwithXXthenumberofsubimagesisautomaticallyappended.CreatefromStrip.Allowsyoutocreateaspritefromastrip.Seethenextsectionformoreinformation.AddfromStrip.Usethistoaddimagesfromastrip.Seethenextsection.CloseSavingChanges.Closestheform,savingthechangesmadetothesprite.Ifyoudon'twanttosavethechanges,clickontheclosebuttonoftheform.

Editmenu

Theeditmenucontainsthefollowingcommands:

Undo.Undothelastchange.Thelast16changescanbeundone.Redo.Redothelastundonechange.Cut.Cutthecurrentlyselectedsubimagetotheclipboard.Youcaneditorusethesubimageinadifferentprogramthisway.However,thetransparencyinformationmightbelost.Copy.Copythecurrentlyselectedsubimagetotheclipboard.Paste.Pastetheimageontheclipboardasanewsubimage.Whenithasnotthecorrectsizeyoushouldindicatehowtochangethis.Whentheimagecamefromadifferentprogram,transparencyinformationmightbelost.Erase.Erasethecurrent,orallimagestoaparticularcolor.Aformopeninwhichyoucanselectthecolorandtheopacity(alpha)value.Apreviewoftheresultitshown.Youcanindicatewhethertoeraseallimagesoronlythecurrentone.Delete.Deletethecurrentlyselectedsubimage.MoveLeft.Movethecurrentlyselectedsubimageonepositiontotheleftinthesequence.MoveRight.Movethecurrentlyselectedsubimageonepositiontotherightinthesequence.AddEmpty.Addanewemptysubimageattheendofthesequence.InsertEmpty.Insertanewemptysubimagebeforethecurrentlyselectedsubimage.Edit.Editthecurrentlyselectedsubimageusingthebuilt-inimageeditor.SetTranparencyBackground.Hereyoucanindicatehowthetransparentareaofthespritesshouldbeshowninthespriteeditor.Youcaneitherusethe(default)blockpattern,oracolorthatyoucanchangebyclickingonthecolorbox.

Transformmenu

Inthetransformmenuyoucanperformanumberoftransformationsontheimages.Formostofthemyoucanchoosewhethertoapplythemonlytothecurrentsubimageortoallimages.

Shift.Hereyoucanshifttheimage(s)anindicatedamounthorizontallyandvertically.Mirror/Flip.Mirrortheimage(s)horizontallyand/orflipthemvertically.Rotate.Youcanrotatetheimage(s)90,180or270degrees,oranarbitraryamount.Scale.Thiscommandscalestheimage(s)(butnottheimagesize!).Youcanindicatethescalefactorandwhethertoscalehorizontallyand/orvertically.Skew.Thiscommandskewstheimage(s)horizontallyand/orverticallywithagivenamount.ResizeCanvas.Hereyoucanchangethesizeofthecanvas.Youcanalsoindicatewheretheimagesareplacedonthenewcanvas.Stretch.Hereyoucanstretchtheimagesintoanewsize.Youcanindicatethescalefactorandthequality.Crop.Thismakestheimagesassmallaspossible.Thisisveryusefulbecausethelargertheimages,themorevideomemoryGameMakerwilluse.Youcanindicatethesizeofatransparentborderaroundtheimages.Ifyouprovideanegativevalue,theoutsideoftheimageswillbecutoff.

Imagesmenu

Intheimagesmenuyoucanperformanumberofoperationontheimages.SomeoftheseareonlyavailableintheProEdition.

CycleLeft.Cyclesallimagesoneplacetotheleft.Thiseffectivelystartstheanimationatadifferentpoint.CycleRight.Cyclesallimagesoneplacetotheright.BlackandWhite.Makestheimage(s)blackandwhite(thatis,grayscale).Colorize.Hereyoucanchangethecolor(hue)oftheimages.Use

theslidertopickthenewhue.Whenyouindicatetoshiftthehuethecolorsareshiftedovertheamountindicatedgivingratherinterestingeffects.ColorizePartial.Hereyoucanchangethecolor(hue)ofpartoftheimages.Youcanselecttheoldhueandatolerancearounditandthenindicatethenewhuewithwhichtoreplacethisrangeofcolors.Thiscanbeusedforinstancetochangeonlythecoloroftheshirtsofplayers.Youcanpicktheoldhuealsobyclickingintheleftimage.Intensity.Hereyoucanchangetheintensitybyprovidingvaluesforthecolorsaturationandthevalueofthenewimages.Invert.Invertsthecolorsintheimages.MakeOpaque.Removealltransparencyinformationfromtheimages,makingthemopaque.EraseaColor.Youcanselectacolor(eitherbyclickingonthecolorboxorbyclickingintheleftimage.Alsoyouspecifyatolerance.Allpixelswithacolorclosethetheselectedcolorwillbemadetransparent.SmoothEdges.Smooththeedgesaroundtheopaquepartoftheimage(s)somewhattomakethemlooknicer.(AstrongereffectcanbecreatedbyusingBlurbutonlyblurringthetransparency;seebelow.Opacity.Hereyoucanchangetheopacity(transparency)forthewholeimage.Youcaneithersetitrelativetothecurrentopacityorabsolute.(Fullytransparentpixelsalwaysstayfullytransparent.)SetAlphafromFile.Youselectanimage.Thelightnessofthepixelsofthatimagewillbeusedastransparencyvalue.Blackpixelswillleadtocompletelytransparentpixels,whilewhitepixelswillleadtoopaquepixels.Whentheimagedoesnothavethecorrectsizeitwillbestretched.OnlyavailableintheProEdition.Fade.Hereyouspecifyacolorandanamount.Thepixelsintheimage(s)arenowfadedtowardsthiscolorwiththegivenamount.Blur.Byblurringtheimagesthecolorsaremixedabit,makingitmorevague.Youcanselectasmall,medium,orlargeblur.Alsoyoucanselectwhethertoblurthecolorvaluesand/orthetransparencyvalues.Onlyblurringthetransparencyvaluesisanicewaytosmooththeboundaryoftheimages.Sharpen.Thisissortofthereverseofblurring.Theimagewillbe

mademoresharp,enhancingtheedges.Youcandoasubtlesharpeningorastrongsharpening.Thespecialsharpeningputsadditionalempasisontheedges,leadingtoafunnyeffect.Youcansharpenthecolorvaluesand/orthetransparencyvalues.Outline.Createanoutlinearoundtheimage.Youareaskedforthecolorandathicknessoftheoutline.Youcanalsoindicatetoplacetheoutlineinsidetheimage.Youcanindicatewhethertoremovetheimageitself,justkeepingtheoutline,andwhethertosmooththeoutline.OnlyavailableintheProEdition.Shadow.Createashadowbehindtheimage.(Thiswillonlyworkwhentheimageispartiallytransparent.)Youindicatethecoloroftheshadowandtheopacity.Alsoyouindicatetherelativepositionoftheshadow.Finallyyoucanindicatewhetheritshouldbeasoftorahardshadow.OnlyavailableintheProEdition.Glow.Createacoloredglowaroundtheimage.Youindicatethecoloroftheglow,theopacityandthethickness.Youcanalsoindicatetoplacetheglowinsidetheimage.OnlyavailableintheProEdition.Buttonize.Turntheimage(s)intoabutton.Youspecifythecolorofthebuttonandtheopacity.Alsoyoumustindicatethethicknessofthebuttonboundaryandwhetheritshouldbesmoothornot.OnlyavailableintheProEdition.GradientFill.Addsagradientfilltotheimage(s).Youspecifythetwocolorsofthefill,theopacity,andthekindoffill.Defaulttheimageisreplacebythegradientalthoughthetransparencyismaintained.ByuncheckingtheReplaceboxthegradientisblendedontotheimage.BycheckingtheChangeTransparencyboxthealphavalueoftheoriginalimageischangedaswell.Youcancreategreateffects.Forexample,makeanimageblack-and-whiteandthenblendagradientonit.OnlyavailableintheProEdition.

Youwillhavetoexperimentwiththesecommandstogetthespritesyouwant.

Animationmenu

Undertheanimationmenuyoucancreatenewanimatedspritesoutofthecurrentsprite.Therearemanyoptionsandyoushouldexperimentabitwiththemtocreatetheeffectsyouwant.Alsodon'tforgetthatyoucanalwayssaveananimatedspriteandlateraddittothecurrentone.Alsoyoucanalwaysaddsomeemptyimagesanddeleteunwantedones.Wewillbrieflygothroughthedifferentpossibilities.

SetLength.Hereyoucanchangethelengthofyouranimation.Theanimationisrepeatedenoughtimestocreatethenumberofframesyouindicate.(Normallyyouwantthistobeamultipleofthecurrentnumberofframes.)Stretch.Thiscommandalsochangesthelengthoftheanimation.Butthistime,framesareduplicatedorremovedtogettherightnumber.Soifyouincreasethenumberofframestheanimationgoesslowerandifyoudecreasethenumberitgoesfaster.Reverse.Well,asyoucouldguessthisreversestheanimation.Soitisplayedbackwards.AddReverse.Thistimethereversesequenceisadded,doublingthenumberofframes.Thisisveryusefulformakinganobjectgoleftandright,changecolorandreturn,etc.Yousometimesmightwanttoremovethedoublefirstandmiddleframethatoccur.TranslationSequence.Youcancreateananimationinwhichtheimageslightlytranslatesineachstep.Youmustprovidethenumberofframesandthetotalamounttomovehorizontallyandvertically.RotationSequence.Createsananimationinwhichtheimagerotates.Youcaneitherchooseclockwiseorcounterclockwiserotation.Specifythenumberofframesandthetotalangleindegrees(360isacompleteturn).(Youmightneedtoresizethecanvasfirsttomakesurethetotalimageremainsvisibleduringtherotation.)Colorize.Createsananimationthatturnstheimageintoaparticularcolor.Fadetocolor.Createsananimationthatfadestheimagetoaparticularcolor.Disappear.Makestheimagedisappearbymakingitmoretransparentineachstep.Shrink.Shrinkstheimagetonothing.Youcanindicatethedirection.Grow.Growstheimagefromnothing.

Flatten.Flattenstheimagetonothinginagivendirection.Raise.Raisestheimagefromagivendirection.Overlay.Overlaystheanimationwithanotherspriteorimageinafile.Youindicatethefileandtheimage(s)fromthatfilearethenplacedontopofthecurrentanimation.Whentheimagefromthefilehasadifferentsizeitisstretched.Morph.Morphstheanimationtoananimationorimagefromafile.Notethatmorphingworksbestifthetwoanimationscoverthesameareaoftheimage.Otherwise,halfwaycertainpixelsdisappearandotherssuddenlyappear.

Inparticularthelasttwocommandsareverypowerful.Forexample,toblowupanobject,addanumberofcopiesandthenanumberofemptyframes.Thenoverlayitwithanexplosionanimation.(Makesurethenumbersofimagesmatch.)Alternatively,morphittotheexplosion.Withsomepracticeyoucanmakegreatsprites.

Strips

Asindicatedabove,spritesarenormallyeitherstoredasanimatedgiffilesorasstripsinPNGfiles,inwhichallsubimagesareplacednexttoeachother.Inthesecondcasethefilenameshouldendwith_stripXXwhereXXindicatesthenumberofsubimages.

However,sometimesspritesarepartofalargerbitmapinwhichthesubimagescanbestorednexttoeachotherorbeloweachotherandmaybethereareseparatinglinesbetweenthem.SuchastripcannotbereadautomaticallyasGameMakerwillnotknowthesizeandpositionofthesubimage.Forexample,thefollowingpieceofastripfilecontainsfourdifferentanimations.

Ifyouwanttopickacertainanimationoutofsuchafileyoumustindicatewheretheimagesare.TothisendyoucanchooseCreatefromStriporAddfromStripfromtheFilemenuinthespriteeditor.Afterindicatingtheappropriatestripimagefile,thefollowingformwillshow:

Attherightyousee(partof)thestripimageyouselected.Attheleftyoucanspecifyanumberofparametersthatspecifywhichsubimagesyouareinterestedin.Notethatoneormorerectanglesintheimageindicatetheimagesyouareselecting.Thefollowingparameterscanbespecified:

Numberofimages.Thisisthenumberofsubimagesyouwanttotakefromthestrip.Imagesperrow.Howmanyimagesoftheonesyouwantarethereperrow.Forexample,bysettingthisto1youwillselectaverticalsequenceofimages.Imagewidth.Widthoftheindividualimages.Imageheight.Heightoftheindividualimages.Horizontalcelloffset.Ifyoudon'twanttoselectthetop-leftimages,youcansetherehowmanyimagesshouldbeskippedhorizontally.Verticalcelloffset.Hereyouindicatehowmanyimagestoskipvertically.Horizontalpixeloffset.Sometimesthereissomeadditionalspaceatthelefttop.Hereyouindicatethisamount(inpixels).YoucanalsousethemousetoindicatetheplacewherethefirstimageshouldstartVerticalpixeloffset.Verticalamountofextraspace.Horizontalseparation.Insomestripstherearelinesoremptyspacebetweentheimages.Hereyoucanindicatethehorizontalamounttoskipbetweentheimages(inpixels).Verticalseparation.Verticalamounttoskipbetweentheimages.

Onceyouselectedthecorrectsetofimages,pressOKtocreateyoursprite.Pleaserememberthatyouareonlyallowedtouseimagescreatedbyotherswhenyouhavetheirpermissionorwhentheyarefreeware.

Editingindividualimages

GameMakerhasabuilt-inimageeditorthatcanbeusedtoeditindividualsubimagesofspritesandbackgroundimages.Tocalltheeditorforasubimageofasprite,selectthesubimageinthespriteeditorandchooseEditImagefromtheImagemenu(ordoubleclickonit).Toeditabackground,openthebackgroundpropertiesforandpressthebuttonEditBackground.

Thebuilt-inimageeditorisprettypowerfulandespeciallysuitedforcreatingspritesandbackgroundsforGameMaker.However,itdoesnothaveallthefeaturesoffull-blownpaintanddrawingpackages.Thebuitl-ineditorisprimarilymeantformakingchangestoimages,notforcreatingspritesandbackgroundsfromscratch.Forthisyouprobablywanttouseaseparatepaintprogram,savetheimagesasPNGfiles,andloadthemintoGameMaker.Youcanalsosetanexternalimageeditorinthepreferences.

Whenyoustarttheimageeditoritwilltypicallylooksasfollows:

Theformshowstheimageinthemiddleandanumberofdrawingtoolsattheleft.Belowthereyoucansetcertainpropertiesofthedrawingtools.Thesewillchangedependingonthetoolyouselect(seebelow).Inthemiddleyouseethecurrentimage.Youcanzoominandoutusingthebuttonsonthetoolbar.Attherightthereisinformationaboutthecolorswithwhichthedraw.Youcansetaseparatecolorfortheleftandtherightmousebutton.Youcanchangethesebyclickingwiththeleftorrightmousebuttoninthecolorselectorimages.Alsoyoucanchangethembyclickingintheboxesatthetopthatrepesentthecolors.BelowthecolorsyouseetheOpacity.Thisindicateshowopaqueortransparentthecoloris.Whenyousetitto255thepixelsyourdrawarefullyopaque.Whenyousetitto0theyarefullytransparent.Normallywhenyoudrawpartiallytransparentpixelstheyareblendedwiththecurrentcolor.BysettingtheColorModetoReplace,thepixelswillbereplacedwiththenewcolor.Finallyatthebottomoftheformthereisastatusbarwithsomeinfomationaboutthecurrentdrawingtool,thepositionofthemouse,thesizeoftheimage,andtheamountofmemoryitrequires.

Drawingtools

Thefollowingdrawingtoolsareavailable(fromlefttoright,toptobottom).

Paint.Withthistoolyoucanpaintontheimage.Youcanusetheleftorrightmousebuttontopaintinthedifferentcolors.Youcanselectthesizeofthepen.Whenholding<Shift>whenstartingtopaintyouonlypainthorizontalorverticallines.Whenholdingthe<Ctrl>keyyoucanselectanewpaintcolor.Spray.Withthistoolyoucansprayontheimage.Sprayislikepaintexceptthatyouuseabrushthatispartiallytransparentatthesides.Youcanusetheleftorrightmousebuttontopaintinthedifferentcolors.Youcanselectthesizeofthebrush.Youcanalsoselectthehardnessofthebrush.Asoftbrushwillbemoretransparentnearthesides.Whenholding<Shift>whenstartingtosprayyouonlypainthorizontalorverticallines.Whenholdingthe<Ctrl>keyyoucanselectanewspraycolor.

Erase.Withthistoolyoucaneraseparttheimage.Itlooksalotlikespraybutyouerasewhatisbelowthemouse.HowmuchyouerasedependsonthetheOpacity.Foravalueof255youerasecompletely.Forasmallervalueyouonlymaketheimageabitmoretransparent.Youcansetthehardnessoftheeraser.Whenholding<Shift>whenstartingtosprayyouonlypainthorizontalorverticallines.ColorPicker.Withthistoolyoucansettheleftorrightmousecolortothecolorofapixelintheimage.Notethatalsotheopacityvalueisset.Line.Withthistoolyoucancandrawstraightlines.Whenholding<Shift>youcandrawhorizontal,vertical,ordiagonallines.Youcansetthewidthofthelineandwhetherisshouldhavearrows.ByselectingAnti-aliasthelineisdrawnwithpartiallytransparentpixelsonthesidetomakeitmoresmooth.Polygon.Withthistoolyoucancandrawaclosedpolygon.Youclickonthepositionofthefirstvertex.Nextyoucaneitherdragthenextvertexorclickonthepositionofthenextvertex.Inthiswayyoucontinue.Youendthepolygonwiththe<Esc>key.Whenholding<Shift>youcandrawhorizontal,vertical,ordiagonallines.Youcansetthewidthofthelineandwhetherthepolygonshouldbefilledornot.ByselectingAnti-aliasthepolygonisdrawnwithpartiallytransparentpixelsonthesidetomakeitmoresmooth.Rectangle.Withthistoolyoucancandrawarectangle.Whenholding<Shift>youcandrawasquare.Whenholding<Ctrl>youdrawtherectanglefromthecenter.Youcansetthewidthofthelineandwhethertherectangleshouldbefilledornot.ByselectingAnti-aliastherectangleisdrawnwithpartiallytransparentpixelsonthesidetomakeitmoresmooth.Ellipse.Withthistoolyoucancandrawanellipse.Whenholding<Shift>youcandrawacircle.Whenholding<Ctrl>youdrawtheellipsefromthecenter.Youcansetthewidthofthelineandwhethertheellipseshouldbefilledornot.ByselectingAnti-aliastheellipseisdrawnwithpartiallytransparentpixelsonthesidetomakeitmoresmooth.RoundedRectangle.Withthistoolyoucancandrawaroundedrectangle.Whenholding<Shift>youcandrawasquare.When

holding<Ctrl>youdrawtheroundedrectanglefromthecenter.Youcansetthewidthofthelineandwhethertheroundedrectangleshouldbefilledornot.ByselectingAnti-aliastheroundedrectangleisdrawnwithpartiallytransparentpixelsonthesidetomakeitmoresmooth.SelectRegion.Withthistoolyoucancanselectarectangularregion.Youcanextendthecurrentselectionbyholdingthe<Shift>key.Alsoyoucanremovepartsbyholdingthe<Ctrl>key.Onceyoumadeaselectionyoucanpickitupwiththemouseanddragittoanewposition.Whenyouusetherightmousebuttonyoumakeacopy.Theselectioncanalsobecutorcopiedtotheclipboard.Itcanbedeletedwiththe<Del>key.Youcanendtheselectionusingthe<Esc>key.SelectwithMagicWand.Inthiscaseyoumaketheselectionbyclickingonapixel.Allconnectedpixelswiththesamecolorwillbeselected.Youcanindicatethetoleranceincolorvaluwithwhichtoselectpixelsandwhetheronlythecolororalsothetransparencyvalueshouldmatch.Youcanextendthecurrentselectionbyholdingthe<Shift>key.Alsoyoucanremovepartsbyholdingthe<Ctrl>key.Youcanmanipulatetheselectionasabove.SelectbySpraying.Inthiscaseyoumaketheselectionbysprayingwiththemouseontheimage.Youcansetthesizeoftheselector.Fortheresttheselectioncanbetreatedasabove.Differentselectiontypescanbecombined.Text.Toaddatextclickontheimage.Apop-upwindowappearsinwhichyoucanenterthetext.Usethe#symboltoinsertanewline.OnceyoupressOKthetextisputintheimage,withaboxaroundit.Youcannowmovethetextbypressingwiththemouseintheboxanddraggingthetext.Youcanchangethetextbyclickingwiththerightmousebuttoninthebox.YoucansettheFontofthetextandhowthedifferentlinesshouldbealligned.Fill.Clickonapixelintheimageandallconnectedpixelswiththesamecolorwillbeturnedintothenewpixel.Youcansetthetolerancewithwhichthecolorshouldmatch.Alsoyoucansetwhethertoonlymatchonthecolorvalueoralsotakethetransparencyvalueintoaccount.NotthatwhentheColorModeissettoBlendthefillcolorisblendedwiththeexistingone.Toreplace

it,settheColorModetoReplace.ChangeColor.Clickonapixelintheimageandallpixelsintheimagewiththesamecolorwillbeturnedintothenewpixel.Youcansetthetolerancewithwhichthecolorshouldmatch.Alsoyoucansetwhethertoonlymatchonthecolorvalueoralsotakethetransparencyvalueintoaccount.NotthatwhentheColorModeissettoBlendthenewcolorisblendedwiththeexistingone.Toreplaceit,settheColorModetoReplace.

Menus

Anumberoffurthercommandsisavailablethroughthemenus.Forsomeofthesethereisacorrespondingbuttononthetoolbar.

Filemenu

New.Createsanew,emptyimage.Youmustindicatethesizeoftheimage.(Whentheimageispartofaspritewithmultipleimagesyoucannotsetthesize.)(Remember,allimagesinaspritemusthavethesamesize.)Open.Openanimagefromafile.Thismenuitemisnotavailablewhentheimageispartofaspritewithmultipleimages.PreviousImage.Onlyavailablewhentheimageispartofaspritewithmultipleimages.Savesthechangesandopenstheprevioussubimage.NextImage.Onlyavailablewhentheimageispartofaspritewithmultipleimages.Savesthechangesandopensthenextsubimage.SaveasPNGFile.SavestheimageasaPNGfile.Nootherfileformatsaresupported.CloseSavingChanges.Closestheform,savingthechangesmadetotheimage.Ifyoudon'twanttosavethechanges,clickontheclosebuttonoftheform.

Editmenu

HereyoufindtheusualcommandstoUndothelastchangeandRedo

thelastundo,todelete,cut,orcopythecurrentselectiontotheclipboard,topastetheimageontheclipboardasaselectionintheimage,andtoselectall.(Notethatwhenusingtheclipboard,transparencyinformationmightbelost.)Twoadditionalcommandsrequireabitmoreexplanation.

ErasetoLeftColor.Thiserasestheimageandreplacesitbytheleftcolor(andopacitysetting).PastefromFile.Youcanselectanimagefromafile.Thisimageisthenpastedintothecurrentimageasaselection.Youcanthenmovethatselectiontotheappropriateplace.

Viewmenu

ZoomOut.Youcanzoomouttoseemoreoftheimage.Youcanalsoholdthe<Ctrl>keyandmovethemousescrollwheeltozoominorout.NoZoom.Setstheimagebacktothenormalsize.ZoomIn.Youcanzoomintomorepreciselydrawinanareaoftheimage.ToggleGrid.Youcantogglethegridonoroff.Notethatthegridisonlyshownwhenyouzoominenough.GridOptions.Hereyoucansetthesizeofthegridandthecolor.Youcanindicatewhethertouseexclusiveorwhendrawingthegrid(mightmakeitmorevisible)andwhetherthedrawingshouldbesnappedtothegrid.ShowPreview.Showapreviewoftheimageintherightbottomcornerinthenormalsize.Thisisinparticularusefulwhenyouarezoominginalottomakesmallchanges.Iftheimageislargerthanthepreviewareyoucanusethemousetodragthepartoftheimageyouwanttosee.Youcanalsodoubleclickonthepreviewimagetoopenaseparatepreviewwindowinwhichyoucanseethecompleteimage.SetTranparencyBackground.Hereyoucanindicatehowthetransparentareaoftheimageshouldbeshowninthespriteeditor.Youcaneitherusethe(default)blockpattern,oracolorthatyoucanchangebyclickingonthecolorbox.

Transformmenu

Thismenucontainsthesametransformationcommandsasinthespriteeditor.Youcanreadabouttheirfunctionthere.NotethatResizeCanvas,Stretch,andCroparenotavailablewhentheimageispartofaspritewithmultipleimages,becauseinthatcasewecannotchangethesizeoftheimage.

Imagemenu

Thismenucontainsthesamecommandsasinthespriteeditor.Youcanreadabouttheirfunctionthere.NotethatsomecommandsareonlyavailableintheProEdition.

Moreaboutsoundsandmusic

Inadvancedmodeyouhavealotmorecontroloverthesoundsandpiecesofmusicyouaddtoyourgame.Whenyouaddasoundresourcethefollowingformwillshow:

Besidesthebuttonstoload,save,andplaysoundstherearealotofsettingsnowthatwillbediscussedhere.

Firstofallyoucanindicatethekindofsound.Fourkindsarepossible.Normalsoundsareingeneralusedforsoundeffectsinwavefiles(althoughtheycanbeusedformidifilesaswell).Multiplenormalsoundscanplayatthesametime.Youcanevenplaymultiplecopiesofthesamesoundsimultaneously.Backgroundmusicissimilartonormalsoundsbutonlyonecanplayatanymoment.Soonceyoustartanewbackgroundsound,thecurrentlyplayingonewillbestopped.Midifilesaredefaultbackgroundmusic.3Dsoundissoundforwhichyoucanapply3Dsettingsthroughspecialfunctions.Youwillonlyneedtheseforadvancedsoundeffects.

SoundfilesarenormallyplayedthroughDirectX.Thisgivesmany

possibilitiesbutislimitedtowaveandmidifiles.Ifyouwanttoplayotherfiles,likemp3files,youshouldselecttheoptiontousethemediaplayer.Thisismuchmorelimitedthough.Novolumechangesoreffectscanbeusedandonlyonepiececanplayatonce.Notethatmidifiles,whenplayedthroughthemediaplayermaysounddifferentfromplayingthemasbackgroundornormalsounds.Thereasonisthatthemediaplayerusesthehardwaresynthesizer(whichisdifferentoneachmachine)whileotherwiseasoftwareversionisused(whichsoundsthesameonallmachines).Preferablydon'tusemp3filesinyougames.Theyneedtobedecompressedwhichtakesprocessingtimeandmightslowdownthegame.Thefactthatthefilesizeissmallerdoesnotmeanthattheyuselessmemory.Also,notallmachinessupportthem.Soyourgamemightnotrunonallmachines.

Secondly,youcanindicatesomesoundeffects,likechorusorecho(onlyintheProEditionofGameMaker!)Youcanselectanycombination.Youcanimmediatelylistentotheresults.(WhenusingGMLcodeyoucanevenchangetheparametersoftheseeffects.)

Alsoyoucanindicatethedefaultvolumeofthesoundandwhethertopanittotheleftortherightspeaker.

Forallsoundsyoucanindicatewhethertheyshouldbepreloadedornot.Whenasoundisplayeditmustbeloadedintoaudiomemory.Ifyoupreloadthesoundthisisdoneatthestartofthegame,makingitimmediatelyavailableforplayback.Whennot,itisloadedthefirsttimeitisused.Thiswillsavememorybutmightgiveasmalldelaythefirsttimethesoundisused.

GameMakerdoesnothaveabuilt-insoundeditor.Butinthepreferencesyoucanindicateexternaleditorsthatyouwanttouseforeditingsounds.IfyouselectedtheseyoucanpressthebuttonlabeledEditSoundtoeditthecurrentsound.(TheGameMakerwindowwillbehiddenwhileyoueditthesoundandreturnswhenyouclosethesoundeditor.)

Moreaboutbackgrounds

Inadvancedmorethereareanumberofadditionaloptionsforbackground.Firstofall,anewbuttonSaveBackgroundhasappeared.Withthisbuttonyoucansavethebackgroundinaproprietaryformat.Thiswillnotonlystoretheimageitselfbutalsoforexampleinformationaboutthetiles(seebelow).Thesefileswillhavetheextension.gmbck.YoucanloadtheminGameMakerandwhilerunningagame.AlsoyoucanalsochangeabackgroundorcreateyourownbackgroundsbypressingthebuttonlabeledEditBackground.Abuilt-inimageeditoropensthathasmanyfeatures.Pleaserealizethatthisisnotafull-blownprogramandifyourequiremoreadvancededitingtoolsyoumightwanttouseaseparatedrawingprogram.FormoreinformationonhowtousetheimageeditorseethesectiononEditingimages.

Sometimesyouwanttouseabackgroundasasetoftiles,thatis,acollectionofsmallerimagesinonebigimage.Whencreatetheroomsyoucanthenaddthesesubimagesatdifferentplacesintheroom.Thisisveryusefulforcreatingnicelookinglevels.Touseabackgroundasatileset,checktheboxlabelledUseastileset.Theformnowchangestolookasfollows:

Youcanindicateanumberofsettingsforthetileset.Inparticularyoucanindicatethewidthandheightofeachtile.(Onlyonesizecanbegiven,sobettermakesurethatalltilesinthesethavethesamesize.Ifyouhavedifferentsizes,createtwoormoretilesets.)Youcanalsoindicatean

offsetwherethetopleftmosttilestarts.Finally,aseparationbetweenthetiles(thisisnormally0or1)canbeindicated.Formoreinformationonusingtiles,seethesectiononAddingTileswhencreatingrooms.

Awordofwarningisrequiredhere.Whenyouputseparatingbordersbetweenthespritesanduseinterpolationbetweenpixels(seetheglobalgamesettings)thiscanresultincracksbetweenthetiles.Bettermakesurethepixelsaroundthetilesactuallymatchwiththepixelsjustinsidethetilestoavoidthis.Youcaneasilyachievethisbyeditingthebackgroundandchangingthecolorofsuchpixels.

Moreaboutobjects

Whenyoucreateanobjectinadvancedmode,youcanchangesomemoreadvancedsettings.

Depth

Firstofall,youcansettheDepthoftheinstancesoftheobject.Whentheinstancesaredrawnonthescreentheyaredrawninorderofdepth.Instanceswiththelargestdeptharedrawnfirst.Instanceswiththesmallestdeptharedrawnlast.Wheninstanceshavethesamedepth,theyaredrawnintheorderinwhichtheywerecreated.Ifyouwanttoguaranteethatanobjectliesinfrontoftheothersgiveitanegativedepth.Ifyouwanttomakesureitliesbelowotherinstances,giveitalargepositivedepth.Youcanalsochangethedepthofaninstanceduringthegameusingthevariablecalleddepth.

Persistentobjects

Secondly,youcanmakeanobjectpersistent.Apersistentobjectwillcontinueexistingwhenyoumovefromoneroomtothenext.Itonlydisappearswhenyouexplicitlydestroyit.Soyouonlyneedtoputaninstanceoftheobjectinthefirstroomandthenitwillremainavailableinallrooms.Thisisgreatwhenyouhaveamaincharacterthatmovesfromroomtoroom.Usingpersistentobjectsisapowerfulmechanismbutalsoonethateasilyleadstoerrors.

Parents

Everyobjectcanhaveaparentobject.Whenanobjecthasaparent,itinheritsthebehavioroftheparent.Stateddifferently,theobjectisasortofspecialcaseoftheparentobject.Forexample,ifyouhave4different

balls,namedball1,ball2,ball3andball4,whichallbehavethesamebuthaveadifferentsprite,youcanmakeball1theparentoftheotherthree.Nowyouonlyneedtospecifyeventsforball1.Theotherswillinherittheeventsandbehaveexactlythesameway.Also,whenyouapplyactionstoinstancesoftheparentobjecttheywillalsobeappliedtothechildren.So,forexample,ifyoudestroyallball1instancestheball2,ball3,andball4instanceswillalsobedestroyed.Thissavesalotofwork.

Often,objectsshouldbehavealmostidenticallybuttherewillbesomesmalldifferences.Forexample,onemonstermightmoveupanddownandtheotherleftandright.Fortheresttheyhaveexactlythesamebehavior.Inthiscasealmostalleventsshouldhavethesameactionsbutoneortwomightbedifferent.Againwecanmakeoneobjecttheparentoftheother.Butinthiscasewealsodefinecertaineventsforthechildobject.Theseevents"override"theparentevents.Sowheneveraneventforthechildobjectcontainsactions,theseareexecutedinsteadoftheeventoftheparent.Ifyoualsowanttoexecutetheparenteventyoucancalltheso-called"inherited"eventusingtheappropriateaction.

Itisactuallygoodpracticeinsuchcasestocreateonebaseobject.Thisbaseobjectcontainsallthedefaultbehaviorbutisneverusedinthegame.Allactualobjectshavethisbaseobjectasparent.Parentobjectscanagainhaveparents,andsoon.(Obviouslyyouarenotallowedtocreatecycles.)Inthiswayyoucancreateanobjecthierarchy.Thisisextremelyusefultokeepyourgamestructuredandyouarestronglyadvisedtolearntousethismechanism.

Thereisalsoaseconduseoftheparentobject.Italsoinheritsthecollisionbehaviorforotherobjects.Letusexplainthiswithanexample.Assumeyouhavefourdifferentfloorobjects.Whenaballhitstheflooritmustchangedirection.Thishastobespecifiedinthecollisioneventoftheballwiththefloor.Becausetherearefourdifferentfloorsweneedtoputthecodeonfourdifferentcollisioneventsoftheball.Butwhenyoumakeonebasefloorobjectandmakethisonetheparentofthefouractualfloorobjects,youonlyneedtospecifythecollisioneventwiththisbasefloor.Theothercollisionswillperformthesameevent.Again,thissavesalotofcopying.

Asindicated,whereveryouuseanobject,thisalsoimpliesthedescendants.Thishappenswhen,inanaction,youindicatethattheactionmustbeappliedtoinstancesofacertainobject.Italsohappenswhenyouusethewith()statementincode(seebelow).Anditworkswhenyoucallfunctionslikeinstance_position,instance_number,etc.Finally,itworkswhenyourefertovariablesinotherobjects.Intheexampleabovewhenyousetball1.speedto10thisalsoappliestoball2,ball3andball4.

Masks

Whentwoinstancescollideacollisioneventoccurs.Todecidewhethertwoinstancesintersect,thespritesareused.Thisisfineinmostcases,butsometimesyouwanttobasecollisionsonadifferentshape.Forexample,ifyoumakeanisometricgame,objectstypicallyhaveaheight(togivethema3Dview).Butforcollisionsyouonlywanttousethegroundpartofthesprite.Thiscanbeachievedbycreatingaseparatespritethatisusedascollisionmaskfortheobject.

Information

ThebuttonShowInformationgivesanoverviewofallinformationfortheobjectthatcanalsobeprinted.Thisisparticularlyusefulwhenyoulooseoverviewofallyouractionsandevents.

Moreactions

Inadvancedmodethereareanumberofadditionalactionsavailablewhichwillbedescribedhere.

Informationonthedifferentadditionalactionscanbefoundinthefollowingpages:

MoreMoveActionsMoreMainActionsMoreControlActionsMoreDrawActionsParticleActionsExtraActions

Moremoveactions

Someadditionalmoveactionsareavailableinadvancedmode.Thefollowingactionsareadded:

SetPathWiththisactionyoucanspecifythattheinstanceshouldfollowaparticularpath.Youindicatethepaththatmustbefollowedandthespeedinpixelsperstep.Whenthespeedispositivetheinstancestartsatthebeginningofthepath.Ifitisnegativeitstartsattheend.Nextyouspecifytheendbehavior,thatis,whatshouldhappenwhentheendofthepathisreached.Youcanchoosetostopthemotion,restartfromthebeginning,restartfromthecurrentposition(whichisthesamewhenthepathisclosed),orreversethemotion.Finallyyoucanindicatethatthepathmustbeseenasabsolute,thatis,thepositionwillbeasindicatedinthepath(thisisusefulwhenyouhavedesignedthepathataparticularplaceintheroom)orrelative,inwhichcasethestartpointofthepathisplacedatthecurrentlocationoftheinstance(endpointwhenspeedisnegative).Seethechapteronpathsformoreinformation.

EndPathUsethisactiontostopthepathfortheinstance.

PathPositionWiththisactionyoucanchangethecurrentpositionoftheinstanceinthepath.Thismustbeavaluebetween0and1(0=beginning,1=end).

PathSpeedWiththisactionyoucanchangethespeedoftheinstanceonthepath.Anegativespeedmovestheinstancebackwardsalongthepath.Setitto0totemporarilystopthemotionalongthepath.

StepTowardsThisactionshouldbeplacedinthestepeventtolettheinstancetakeasteptowardsaparticularposition.Whentheinstanceisalreadyatthepositionitwillnotmoveanyfurther.Youspecifythepositiontomoveto,

thespeedwithwhichtomove,thatis,thesizeofthestep,andwhetherthemotionshouldstopwhenhittingasolidinstanceorwhenhittinganyinstance.

StepAvoidingThisisaverypowerfulmotionaction.Itshouldbeplacedinthestepevent.Likethepreviousactionitletstheinstancetakeasteptowardsaparticularposition.Butinthiscaseittriestoavoidobstacles.Whentheinstancewouldrunintoasolidinstance(oranyinstance)itwillchangethedirectionofmotiontotrytoavoidtheinstanceandmovearoundit.Theapproachisnotguaranteedtoworkbutinmosteasycasesitwilleffectivelymovetheinstancetowardsthegoal.Formorecomplicatedcases,therearemotionplanningfunctions.Youspecifythepositiontomoveto,thespeedwithwhichtomove,thatis,thesizeofthestep,andwhetherthemotionshouldavoidsolidinstancesoranyinstance.

Moremainactions

Someadditionalmainactionsareavailableinadvancedmode.Thefollowingactionsareadded:

SetTimeLineWiththisactionyousettheparticulartimelineforaninstanceofanobject.Youindicatethetimelineandthestartingpositionwithinthetimeline(0isthebeginning).Alsoyouindicatewhetherthetimelineshouldstartimmediatelyandwhetheritshouldloopattheend.

TimeLinePositionWiththisactionyoucanchangethepositioninthecurrenttimeline(eitherabsoluteorrelative).Thiscanbeusedtoskipcertainpartsofthetimelineortorepeatcertainparts.

TimeLineSpeedWiththisactionyoucanchangethespeedofthetimeline(eitherabsoluteorrelative).Aspeedof1isthenormalspeed.Whenyoue.g.setitto2theactionswillhappentwiceasfastandwhenyousetitto0.5twiceasslow.Youcanalsosetanegativespeed,inwhichcasethetimelineisplayedbackwards.

StartTimeLineThisactionstartsthetimelinefromitscurrentposition(ifitispausedorstopped).

PauseTimeLineThisactionpausesthetimeline.Usethestartactiontoletitcontinue.

StopTimeLineThisactionstopsthetimelineandsetsthepositionbackto0.

SplashTextWiththisactionyoucanshowatextfile.Thiscaneitherbea.txtfileora.rtf(RichTextFormat)file(noimagesorembeddedobjectsareshown

though).Youspecifythefilename.Makesurethefileexists.YoushouldeitherdistributeitwiththegameorincludeitinthegamethroughIncludeFilesintheResourcesmenu.(Notethatnoscrollbarwillbeshownnoristhereanotherwaytoscrollthetext.Sothetextmustfitthewindow.)ThisactionisonlyavailableintheProEdition.

SplashImageWiththisactionyoucanshowanimagefile.Mostcommonimagefiletypesaresupported.Youspecifythefilename.Makesurethefileexists.YoushouldeitherdistributeitwiththegameorincludeitinthegamethroughIncludeFilesintheResourcesmenu.Youcane.g.usethistocreateaseriesofimagesashelpforyourgame.Notincludingtheimagesinthegameitselfwillreducegamesizeandimprovegameloadingtime.ThisactionisonlyavailableintheProEdition.

SplashWebpageWiththisactionyoucanshowawebpage.Youprovidetheurlandwhetheritshouldbeshowninthegamewindoworinthedefaultwebbrowser.Theurlcanbetheaddressofawebsite,forexamplehttp://www.yoyogames.com)orcanbethefilenameforalocalhtmlfile.Notehoweverthatyoumustprovidethefullpathforthistowork(whichisnotthecasefortheothersplashactions).Soyoubestuseasurlsomethinglike""+working_directory+"\index.html".(Thefirsttwoquotesarerequiredtoindicatethisisanexpressionratherthanastring.)YoushouldeitherdistributethefilewiththegameorincludeitinthegamethroughIncludeFilesintheResourcesmenu.Youcane.g.usethistocreatefancyhelppagesforyourgame.ThisactionisonlyavailableintheProEdition.

SplashVideoWiththisactionyoucanshowavideo/moviefile.Youspecifythefilenameandwhetherismustbelooped.Makesurethevideofileexists.YoushouldeitherdistributeitwiththegameorincludeitinthegamethroughIncludeFilesintheResourcesmenu.ThisactionisonlyavailableintheProEdition.

SplashSettings

Withthisactionyoucanchangecertainsettingsforthesplashscreensthatyoudisplaywiththepreviousactions.Youcanprovidethecaptionforthehelpwindow(onlywhenitisshowninaseparatenormalwindow),youcanindicatewherethesplashscreensmustbeshown(insidethegamewindow,inanormalwindow,orfullscreen),youcanindicatewhetheraclosebuttonmustbeshowninthetoprightcornerofthesplashscreenandwhetherpressingtheescapekeyorclickingwithamouseinthesplashscreenwillclosethesplashscreen.(Forwebpagesclickingwiththemousewillnotworknorwilltheescapekeyworkunlesstheclosebuttonisshown.)ThisactionisonlyavailableintheProEdition.

ReplaceSpriteThisactioncanbeusedtoreplaceaspritefromthecontentsofafile.Youindicatethespriteyouwanttoreplace,thefilenameandthenumberofsubimagesinthesprite.Manydifferentimagesfileformatsaresupported,e.g..bmp,.jpg,.tif,and.gif.Foragiffilethenumberofsubimagesisautomaticallydecidedbasedonthenumberofsubimagesinthegiffile.Othersettingsforthesprite,e.g.whetheritistransparentornot,arenotchanged.Youcanusethisactiontoavoidstoringallspritesintheprogramitself.Forexample,atthebeginningofalevelyoucanreplacespritesbytheactualcharacterspritesyouwanttouse.DON'Tchangeaspritethatisatthatmomentbeingusedinaninstanceintheroom.Thismightgiveunwantedeffectswithcollisions.ThisactionisonlyavailableintheProEdition.

ReplaceSoundWiththisactionyoucanreplaceasoundbythecontentsofafile(.wav,.mid,or.mp3).Youspecifythesoundandthefilename.Thisavoidshavingtostoreallthesoundsinthegameitself.Forexample,youcanusedifferentpiecesofbackgroundmusicandpicktheoneyouwanttoplay.DON'Tchangeasoundwhileitisplaying.ThisactionisonlyavailableintheProEdition.

ReplaceBackgroundWiththisactionyoucanreplaceabackgroundbythecontentsofafile.Manydifferentimagesfileformatsaresupported,e.g..bmp,.jpg,.tif,and

.gif.Youspecifythebackgroundandthefilename.Thisavoidshavingtostoreallthebackgroundsinthegameitself.DON'Tchangeabackgroundthatisvisible.ThisactionisonlyavailableintheProEdition.

Morecontrolactions

Someadditionalcontrolactionsareavailableinadvancedmode.Thefollowingactionsareadded:

ExecuteScriptWiththisactionyoucanexecuteascriptthatyouaddedtothegame.Youspecifythescriptandthemaximal5argumentsforthescript.

CallParentEventThisactionisonlyusefulwhentheobjecthasaparentobject.Itcallsthecorrespondingeventintheparentobject.

Moredrawactions

Thefollowingadditionaldrawactionisavailableinadvancedmode:

SetFontYoucansetthefontthatisfromthismomentonusedfordrawingtext.Thismustbeoneofthefontresourcesyouhavedefine.IfyouchooseNoFontadefault12pointArialfontisused.

Particleactions

AsetofactiondealingwithparticlesisavailableontheExtratab.TheseactionsareonlyavailableintheProEditionofGameMaker.

Particlesystemsaremeanttocreatespecialeffects.Particlesaresmallelements(representedbyapixeloralittleshape).Suchparticlesmovearoundaccordingtopredefinedrulesandcanchangecolorwhiletheymove.Manysuchparticlestogethercancreatee.g.fireworks,flames,rain,snow,starfields,flyingdebris,etc.

GameMakercontainsanextensiveparticlesystemthatcanbeaccessedthroughfunctions.Amorelimitedparticlesystemcanbeaccessedthroughtheactionsdescribedbelow.

Aparticlesystemcandealwithparticlesofdifferenttypes.Aftercreatingtheparticlesystemthefirstthingtodoisspecifytheparticletypes.Usingtheactionsbelowyoucanspecifyupto16typesofparticles.Eachtypehasashape,asize,astartcolorandanendcolor.Thecolorslowlychangesfromthestartcolortotheendcolor.Particleshavealimitedlifetime.Inthetypeyouspecifytheminimalandmaximallifetimeoftheparticles.Particlesalsohaveaspeedandadirection.Finally,gravityandfrictioncanworkonparticles.

Afteryouspecifytheparticletypesyoumustcreatethematplacesintheroom.Youcaneitherburstanumberofparticlesofaparticulartypefromaplaceoryoucancreateaconstantstreamofparticlesappearing.Particlesappearatemitters.Theparticlesystemcanhaveupto8

emittersworkingatthesametime.Soafteryoucreatetheparticletypesyoumustcreatetheemittersandtellthemtoburstorstreamparticles.

Hereisthecompletesetofactions.Bestexperimentwiththemtogettherequiredeffect.

CreatePartSystemThisactioncreatestheparticlesystem.Itmustbecalledbeforeanyotheractionscanbeused.Youonlyneedtocallitonce.Youcanspecifythedepthatwhichtheparticlesaredrawn.Ifyouusealargepositivedepththeparticlesappearbehindtheinstances.Ifyouuseanegativedepththeyappearinfrontoftheinstances.

DestroyPartSystemThisactiondestroystheparticlesystem,freeingallitsmemory.Don'tforgettocallthis(e.g.whenyoumovetoadifferentroom)becauseparticlesystemsusealotofstorage.

ClearPartSystemThisactionremovesalltheparticlescurrentlyvisible.Itdoesnotstoptheemitterssonewparticlesmightbecreatedagainifyouhavestreamingemitters(seebelow).

CreateParticleWiththisactionyoucreateaparticletype.Youcanchooseoneofthe16typesavailable.Fortheparticletypeyoucanspecifyitsshapeorthespritetobeusedforit.Ifyouspecifyaspritethespritewillbeused.Ifyousetthespritetonosprite,theshapewillbeused.Thereareanumberofinterestingbuilt-inshapes.Youalsoindicateditsminimalandmaximalsize(whentheparticleappearsarandomvaluebetweentheseboundsisused).Finallyyouspecifytheincreaseinsizeineachstep.Foradecrease,useanegativevalue.Notethatonlyaparticletypeiscreated,notanactualparticle.Forthisyouneedemitters(seebelow).

ParticleColorAparticlecanhaveacolor(defaultthecoloriswhite).Withthisactionyoucansetthecolortobeusedforaparticulartype.Youmustindicatetheparticletypethecolorisdefinedfor.Nextyouspecifyhowacoloris

applied.Eitherarandomcolorischoosenbetweentwogivencolors,orthecolorstartswiththefirstcolorandthangraduallyoverthelifetimeoftheparticle,itchangestothesecondcolor.Bothcolorsmustbegiven.Finallyyoucanindicatethealphatransparency.Youspecifythetransparencyatthemomenttheparticleiscreatedandwhenitdies.Thetransparencyslowlychangesbetweenthesevalues.Itisnormallynicetodecreasethealphavalueoverthelifetimeofaparticle.

ParticleLifeAparticlelivesforalimitednumberofsteps.Afterthisisdisappears.Withthisactionyousetthelifetimeforaparticletype.Yougivetwolimitingvaluesandtheactuallifetimeischosenrandomlybetweenthem.

ParticleSpeedWiththisactionyoucansetthespeedanddirectionofmotionforaparticletype.Againyougivetwolimitsandtheactualvalueischosenrandomlybetweenthem.Forexample,tomaketheparticlemoveinarandomdirection,give0and360forthelimitsforthedirection.Youcanalsospecifyafriction.Thisamountissubtractedfromthespeedineachstepuntilitbecomes0.(Youcanmakeaparticlespeedupbyusinganegativefriction.)

ParticleGravityWiththisactionyousettheamountofgravityanddirectionofgravityforaparticularparticletype.270isdownwards.

ParticleSecondaryThisisabitmorecomplicated.Particlescancreateotherparticlesduringtheirlifetimeandwhentheydie.Withthisactionyoucanspecifythis.Youcandefinethetypeandnumberofparticlesthatmustbecreatedateachstepduringthelifetimeandyoucanspecifythetypeandnumberofparticlesthatmustbecreatedwhentheparticledies.Beverycarefulhere.Youcaneasilycreatehugenumbersofparticlesinthisway,slowingdownthesystemconsiderably.Forthenumbersyoucanalsouseanegativevalue.Anegativevaluexmeansthatineachstepaparticleiscreatedwithchance-1/x.Soforexample,ifyouwanttogenerateasecondaryparticleaboutevery4steps,useavalueof-4.

Secondaryparticlesaregreatforcreatingeffectsliketailsofparticlesorexplodingparticles.

CreateEmitterThisactioncreatesaparticleemitter.Particlesaregeneratedbyemitters.Youcanhaveuptoeightemitters.Choosetheemitterandspecifytheshapeofitanditssizeandposition(intheformofaboundingbox).

DestroyEmitterThisactiondestroystheindicatedemitter.Notethatexistingparticlesthatcamefromthisemitterarenotremoved.

BurstfromEmitterEvenifyoudefinedaparticletypeandanemittertherearestillnoparticles.Youstillhavetotelltheemittertogeneratetheparticles.Withthisactionyoutellaparticularemittertogenerateagivennumberofparticlesofagiventype.Alltheseparticlesaregeneratedatonce.Forthenumberyoucanalsouseanegativevalue.Anegativevaluexmeansthataparticleiscreatedwithchance-1/x.Soforexample,ifyouwanttogenerateaparticlewithachanceof25percent,useavalueof-4.

StreamfromEmitterWiththisactionyoutellaparticularemittertostreamagivennumberofparticlesofagiventype.Ineachstepthisnumberofparticlesisgenerated,leadingtoacontinuousstreamofparticles.Theemitterwillcontinuestreamingparticlesuntilyoudestroyitortellittostream0particles.Forthenumberyoucanalsouseanegativevalue.Anegativevaluexmeansthatineachstepaparticleiscreatedwithchance-1/x.Soforexample,ifyouwanttogenerateaparticleaboutevery4steps,useavalueof-4.

Extraactions

OntheExtratabtherealsoareanumberofactionsrelatedtotheplayingofCDs.TheseactionsareonlyavailableintheProEditionofGameMaker.

PlayCDWiththisactionyoucanplaysometracksfromaCDinthedefaultCD-drive.Youspecifythestartingtrackandthefinaltrack.

StopCDStopsthecurrentlyplayingCD.

PauseCDPausesthecurrentlyplayingCD.

ResumeCDResumesapausedCD.

CheckCDIfthereisaCDinthedefaultdrivethenthenextactionisexecuted.

CheckCDPlayingIfaCDisplayinginthedefaultdrivethenthenextactionisexecuted.

Finally,thereareanadditionalactionthatcanbeusefulincertaingames.

SetCursorYoucanusethisactiontoreplacethewindowsmousecursorbyasprite.Youspecifythespriteandwhetherthewindowsmousecursorshouldstillbeshown.Thespritecanbeanimated.Notethatthespritewillonlybeshownintheroom,notintheareaoutsideit.

Constants

ThisfunctionalityisonlyavailableintheProEditionofGameMaker.

Inadvancedmodeyoucandefineconstantsthatyoucanuseinscriptsandinvaluesforactions.Eachconstanthasanameandavalue.Namesshouldfollowthesamerulesasvariables,thatis,theymuststartwithaletterorunderscoresymbolandfurtherconsistofletters,digitsorunderscoresymbols.Youarethoughstronglyrecommendedtomakeallyourconstantseasilydistinguishable.Ausualconventionistouseonlycapitallettersandunderscores.

TodefineconstantsyouchoseDefineConstantsfromtheResourcesmenu.Thefollowingformwillshow(inwhichalreadysomeconstantshavebeendefined):

Atthetopyouseetheconstants.Attheleftthereisthenameandattherightthevalue.Youcanselectthenameorvaluewiththemouseandchangeitbytyping.Avalueofaconstantshouldbeaconstantexpression.Thatis,itiseitheraconstantnumberorastring(withquotesaroundit)oritisanexpression.Theexpressionisevaluatedbefore

anythingelsehappensinthegame.Soitforexamplecannotreferencethecurrentroom,instances,orscripts.Butitcancontainthebuilt-inconstantsandthenamesofresources.

YoucanappendaconstantattheendofthelistusingthebuttonAdd(orbypressingEnter)anddeleteitusingDelete.Youcanalsoinsertaconstantabovethecurrentselectedconstant.Therearealsobuttonstoclearallconstants,tomovethemupordowninthelist,andtosortthembyname.

Finallyyoucansaveallconstantstoatextfileorloadthemfromatextfile.Thisisusefulwhenyouwanttostorecollectionsofusefulconstantsforlateruse.Whenloadingconstantstheyareappendedtothecurrentlist.Thetextfilecanalsobeeditorusingatexteditor.EachlinecontainsaconstantdefinitionoftheformNAME=VALUE.

Itisgoodpractisetoputanyvaluethatyouusemultipletimesinaconstant.Also,ifyouarenotcompletelysureaboutacertainvalueyoubetterputitinaconstantasitisaloteasiertochangetheconstantsthantofindthevaluesinthescriptsandactionsandchangethemthere.

Triggerevents


Inadvancedmodeanewtypeofeventsisavailable:triggerevents.Triggereventsyoucandefineyourself.Youspecifytheconditionwhentheeventmustbeexecuted.TodefinetriggereventsyouchoseDefineTriggersfromtheResourcesmenu.Thefollowingformwillshow(inwhichalreadysometriggershavebeendefined):

Attheleftyouseealistofalltriggersthathavebeendefined.Initiallythislistisempty.Belowtherearesomebuttonswiththefollowingfunction:

Add.Usethisbuttontoaddanewtriggereventtothelist.Delete.Deletesthecurrentlyselectedtriggereventtothelist.Becarefultoneverdeleteatriggereventthatisusedinanobject.Itmightleadtounexpectedresults.Load.Loadsacollectionoftriggersfromafile.Suchafilemusthaveextension.gmtrg.Thetriggersfromthefileareaddedtothelistoftriggers.Save.Savesthecollectionoftriggerstoafile.Suchafilemusthaveextension.gmtrg.Inthiswayyoucancreateyourowncollectionsof

usefultriggersthatyoucanuseindifferentgames.Clear.Clearsthelistoftriggers.Becarefultoonlyusethiswhennoobjectusesanytriggerevent.

OnceyouarefinishedyoucanpresstheOKbuttontosavethechanges.Ifyoudonotwanttosavethechanges,closetheformwiththecrossinthetoprightcornerandindicatethatyoudonotwanttosavechanges.

Definingatrigger

Onceyouaddedatriggeryoushouldfillinitsproperties.Firstofallyoumustgivethetriggeraname.Thisnamewillappearinthemenuwithavailabletriggersandintheeventlistsforobjects.Nextyoumustspecifytheconditionthatwilltriggertheevent.ThisisapieceofGML-code.Itmustcontainareturnstatementthatreturnsatrueorfalsevalue.Thetriggerwillfirewhenthereturnvalueistrue.Herearesomeexamples.

AssumeyouwanttocreateaneventthathappenswhentheplayerpressesboththeControlkeyandtheAkey.Forthisyoucanusethefollowingcondition:

{

returnkeyboard_check(ord('A'))&&

keyboard_check(vk_control);

}

Youcanputcompletescriptsintheconditionaslongastheresomewhereisareturnstatement.Forexample,tohaveaneventthathappenwhenthenumberofballsisbetween3and5,youcanusethefollowingcondition:

{

varn;

n=instance_number(obj_ball);

return(n>=3)&&(n<=5);

}

Youcancreatemanyothertypeoftriggerevents.Forexampleevents

thatcheckforcombinationsofkeysandmousebuttons,eventsthatcheckwhetheryouareneartoanenemy,eventstocheckwhetheryoucollectedenoughmoneyorscore,etc.

Iftheconditiongetsabitlongyoumightwanttoedititinthecodeeditorinstead.TothatendpressthebuttonUsecodeeditor.

Afteryouspecifiedtheconditionyoushouldspecifywhentheconditionistested.Therearethreeoptionshere.Youcantesttheconditionatthebeginningofastep(justbeforethebeginstepevent),inthemiddle(justbeforethenormalstepevent)orattheend(justbeforetheendstepevent).Mostofthetimethedefaultmiddlepositionisfinebutincertaincasesyouneedtheothermoments.

Finally,whenyoualsowanttocalltheeventfromcodeyoucanspecifyaconstantwithwhichyoucanreferincodetotheevent.SeeChapter4formoredetailsaboutcallingeventsfromcode.

Usingatrigger

Onceyouhavedefinedyourscriptsyoucanusethemwhendefiningobjects.WhensettingtheobjectpropertiesandclickonAddEvent,youcannowselectTriggerevents.

Inthedrop-downmenuthatappearsyoucanselectthetypeoftriggereventyouwanttouse.Nowyoucanaddactionstothiseventinthesamewayasyouaddactionstootherevents.

Includingfilesinstand-alonegames


Ashasbeenindicatedbefore,youcancreatestand-aloneversionsofyourgame.Sometimesyourgamewilluseadditionalfiles.Forexampleyoumightwanttoincludevideofilesortextfilesthatareusedinthegame.InsomecasesyouwanttoaddDLLsorimagesandsoundsthatareloadedduringtherunningofthegame.Youcanprovidethesetogetherwiththestand-aloneexecutablebutitissometimeseasiertoincludetheminthefile.Inthiswayonlyonefileneedstobedistributed.Includedfileswilldefaultbeexportedwhenthegamestarts.

YoucanindicatethefilesyouwanttoincludeintheexecutableinbychoosingIncludedFilesfromtheResourcesmenu.Thefollowingformwillbeshown:

Atthetopoftheformisalistoffilestoinclude.UseAddtoaddanewfiletothelist,Changetochangeaselectedfile,Deletetodeletetheselectedfile,andCleartoclearthecompletelist.Whenaddingorchanginganentry,thefollowingformwillpopup:

Hereyoucanindicateanumberofproperties.YoucanpresstheLoadbuttontoindicatewhichfilemustbeincluded.YoucanchangetheFileNameifyouwanttosavethefileunderadifferentnamethantheoriginalfilename.

Thereareanumberofoptionsyoucanset.WhenyoucheckStoreintheeditablegmkfiletheincludedfileinnotonlyaddedtotheexecutablebutalsototheeditableversionofthegame.Theadvantageisthatyoucane.g.sendtheeditableversiontosomebodyelseandcanbesurethefileisstillthere.Also,youcanremovetheincludedfileifyouwantormoveitelsewherewithoutproblems.Thedisadvantageisthattheeditableversionofthegamebecomeslargerandtakeslongertoload.

CheckingtheoptionFreememoryafterexportmeansthatafterthefilehasbeenexported(whenrunningthegame)itwillberemovedfrommemory.Ifyouwanttobeabletoexportitagainlateryoushoulduncheckthisoption.Ifafilethatisexportedalreadyexistsitisnormallynotwritten.YoucanchangethisbehaviorbycheckingOverwriteexistingfiles.Also,whenthegameisfinishedthefilesarenormallynotremoved(unlesstheyareinthetemporaryfolderwhichiscompletelyremoved).YoucanchangethisbycheckingRemoveatgameend.

Awordofwarningisinplacehere.Ifyouaretestingyourgame,theworkingdirectoryofthegameisthedirectorywherethe.gmkfileis

stored.Ifyourincludefilesarealsostoredhereandyouchoosetoremovethemattheendofthegameyoumightloosethemalltogether!Sobetternotstorethesefileswiththe.gmkfilebute.g.inasubfolder!

Finallyyoucanindicatetowhatfolderthefilesareexported.Therearefouroptionshere.Inthedefaultsituationthefilesareexportedinthefolderwherethestand-alonegameisstored.Thisisalsotheworkingdirectoryforthegame.Sothegamecanjustusethefilenamestoaccessthem(nopathsarerequired).Thisworkswellifthestand-aloneisstorede.g.ontheharddiskbutwillfailifitisstoredonaread-onlydevice,e.g.onaCD.

Thesecondpossibilityistoindicatethatthefilesmustbeexportedintothetemporaryfolderthatiscreatedduringtherunningofthegame.Ifyouselectthisoptionyouwillneedtoprovidethepathtothetemporaryfolderwhenyouusethefilenameduringthegame.Thispathcanbeobtainedusingthebuilt-invariabletemp_directory.Don'tforgettoaddthebackslashinthiscase.Sotoe.g.playavideofileyoumighttypeinthefollowingpieceofcode:

{

splash_show_video(temp_directory+'\movie.avi',true);

}

Realizethatthistemporaryfolderisremovedoncethegameisfinished.Soyoue.g.cannotstoresavegamesorspecialinformationinthiscase.OnlychoosethisoptionwhenyouwantthegametoberunfromaCDorwhenyoudonotwriteanyfilesfromwithinyourgame.

Thethirdoptionistoindicatethefoldertowhichthefilemustbeexportedyourself.Ifitdoesnotexistitwillbecreated.E.g.youcouldspecifyC:\MyGame.(Notethatyouneedtoprovideafullpatghandthatyoushouldnotincludeabackslashattheend.)Thisisonlyallowedwhenthegamedoesnotruninsecuremode.

Finally,youcanindicatenottheexportthefileautomatically.Inthiscaseyoushouldusee.g.thefunctionexport_include_file(fname)toexportit

yourselfwhenrequired.

Moreaboutrooms

RoomsinGameMakerhavemanyoptions.Beforeweonlytreatedthemostimportantones.Inthischapterwewilldiscusstheotheroptions.Whenyouopentheroomforminadvancedmodeitlooksasfollows:

Asyouwillsee,somenewbuttonshavebeenaddedtothetoolbar.Therearebuttonstosorttheinstanceshorizontallyorvertically.Thisisusefulwheninstancepartiallyoverlap.(Whenaddingtilesthesebuttonsandtheothersworkonthetilesratherthantheinstances.)Alsotherearebuttonstolockallinstancesorunlockallinstances.Lockedinstancescannotbemovedordeleted.Thisprotectsyouagainstincidentallyremovinginstances.(However,whenusingthetoolbarbuttonstodeleteorshiftallinstances,alsothelockedonesaredeletedorshifted.)Usingtherightmousebuttonmenu(hold<Ctrl>andrightclickonaninstance)youcanalsolockorunlockindividualinstances.

Finally,youcanindicatethatyouwanttouseanisometricgrid.Thisisveryusefulwhencreatingisometricgames.Firstofall,thegridlinesnowrundiagonally.Alsothesnappingofinstancesisdifferent.(Itworksbest

whentheoriginoftheinstanceisatthetopleftcornerasisdefault.)

Alsotherearetwonewtabswhichwewilldiscussbelow.

Informationonthedifferentadvancedroomoptionscanbefoundinthefollowingpages:

AdvancedsettingsAddingtilesViews

Advancedsettings

Thereweretwoaspectsinthesettingstabthatwehavenotyetdiscussed.Firstofall,thereisacheckboxlabeledPersistent.Normally,whenyouleavearoomandreturntothesameroomlater,theroomisresettoitsinitialsettings.ThisisfineifyouhaveanumberoflevelsinyourgamebutitisnormallynotwhatyouwantinforexampleanRPG.Heretheroomshouldbethewayyouleftitthelasttime.CheckingtheboxlabeledPersistentwilldoexactlythat.Theroomstatuswillberememberedandwhenyoureturntoitlater,itwillbeexactlythesameasyouleftit.Onlywhenyourestartthegamewilltheroombereset.Actually,thereisoneexceptiontothis.Ifyoumarkedcertainobjectsasbeingpersistent,instancesofthisobjectwillnotstayintheroombutmovetothenextroom.

Secondly,thereisabuttonlabeledCreationcode.HereyoucantypeinapieceofcodeinGML(seelater)thatisexecutedwhentheroomiscreated.Thisisusefultofillincertainvariablesfortheroom,createcertaininstances,etc.Itisimportanttounderstandwhatexactlyhappenswhenyoumovetoaparticularroominthegame.

First,inthecurrentroom(ifany)allinstancesgetaroom-endevent.Nextthenon-persistentinstancesareremoved(nodestroyeventisgenerated!).Next,forthenewroomthepersistentinstancesfromthepreviousroomareadded.Allnewinstancesarecreatedandtheircreationeventsareexecuted(iftheroomisnotpersistentorhasnotbeenvisitedbefore).Whenthisisthefirstroom,forallinstancesthegame-starteventisgenerated.Nowtheroomcreationcodeisexecuted.Finally,allinstancesgetaroom-startevent.

So,forexample,theroom-starteventscanusevariablessetbythecreationcodefortheroomandinthecreationcodeyoucanrefertotheinstances(bothnewonesandpersistentones)intheroom.

Thereisonefurtheroption.Inthepop-upmenuwhenyourightclickonaninstancewiththe<Ctrl>keyyoucannowindicatesomecreationcodeforthespecificinstance.Thiscodeisexecutedwhentheroomisstarted,justbeforethecreationeventoftheinstanceisexecuted.Thisisveryusefultoe.g.setcertainparametersthatarespecifictotheinstance.

Addingtiles

Youcanalsocreateso-calledtiledbackground.Theideabehindthisisasfollows:Inmanygamesyouwillwanttohavenicelookingbackgrounds.Forexample,inamazegame,thewallsofthemazeshouldnicelymatchup,andinplatformgamesyouliketoseebeautifullydrawnplatforms,trees,etc.YoucandothisinGameMakerbydefiningmanydifferentobjectsandcomposingyourroomsfromtheseobjects.Theproblemthoughisthatthistakesalotofwork,useslargeamountsofresources,andmakesthegamesrunslowlybecauseofthemanydifferentobjects.Forexample,tocreatenicewallsinmazegamesyouneedasastart15differentlyshapedwallobjects.

Thestandardwayout,usedinmanygames,isthatthewallsandotherstaticobjectsareactuallydrawnonthebackground.But,youmightask,howdoesthegameknowthatanobjecthitsawallifitisdrawnonthebackgroundonly?Thetrickisasfollows:Youcreatejustonewallobjectinyourgame.Itmusthavetherightsizebutitdoesnotneedtolooknice.Whencreatingtheroom,placethisobjectatallplaceswherethereisawall.And,herecomesthetrick,wemakethisobjectinvisible.Sowhenplayingthegameyoudon'tseethewallobjects.Youseethebeautifulbackgroundinstead.Butthesolidwallobjectsarestillthereandtheinstancesinthegamewillreacttothem.

Youcanusethistechniqueforanyobjectthatisnotchangingitsshapeorposition.(Youcannotuseitwhentheobjectmustbeanimated.)Forplatformgames,youprobablyneedjustonefloorandonewallobject,butyoucanmakebeautifullylookingbackgroundswhereitlooksasifyouwalkongrass,ontreebranches,etc.

Toaddtilestoyourroomyoufirstneedtoaddabackgroundresourcetoyourgamethatcontainsthetiles.Ifyouwanttohaveyourtilespartiallytransparent,makesureyoumakethebackgroundimagetransparentwhenloadingit.Whenaddingthebackgroundresourceindicatethatitmustbeusedasatileset.Nextindicatethesizeofeachtileandwhetherthereisroombetweenthetiles,aswasindicatedinthechapteron

backgroundresources.

Now,whendefiningyourroom,clickonthetabtiles.Thefollowingformisshown(actually,wealreadyaddedsometilesinthisroomandswitchedoffthegrid).

Atthelefttopthereisthecurrentsetoftilesused.Toselecttheset,clickonthemenubuttonbelowitandselecttheappropriatebackgroundimage.

Nowyoucanaddtilesbyselectingthetileyouwantatthetopleft,andnextclickingattheappropriateplaceintheroomattheright.Thisworksinexactlythesamewayasforaddinginstances.Underlyingtilesareremoved,unlessyouunchecktheboxDeleteunderlying.Youcanusetherightbuttontodeletetiles.Holdthe<Shift>keytoaddmultipletiles.Andholdthe<Ctrl>keytomovetilestoanewplace.The<Alt>keywillavoidsnappingtothegird.Alsothereisagainapop-upmenuwhenyouholdthe<Ctrl>keyandclickonatilewiththerightmousebutton.Thebuttonsinthetoolbarwillnowclearalltiles,shiftalltiles,sortthetilesorlock/unlockthem.(Actuallytheyonlyoperateonthecurrentlayer;seebelow.)

Insomesituationsyoumightwanttoputapartofthebackgroundinthe

roomthatisnotexactlythesizeofatileorconsistsofmultipletiles.Thiscanbedoneasfollows.Inthetop-leftimagepresstheleftmousebuttonwhileholdingthe<Alt>key.Nowyoucandraganareawhichyoucanthenplaceintheroominthesamewayastiles.Toselectmultipletiles,holdthe<Shift>key.Notethatthisonlyworkscorrectlywhenthereisnoseparationbetweenthetiles.Ifyouwanttoselectanareathatismultipleoftheroomgridsize,holdthe<Ctrl>keyratherthanthe<Shift>key.(Notethatyoucanactuallychangethekeyyouholdduringthedragging.Thiscansometimesbeuseful.)

Tilescanbeplacedinlayersatdifferentdepths.Atthebottomyouseethecurrentdepth.Defaultthisis1000000whichisnormallybehindallinstances.Sotheinstanceswillmoveinfrontofthetiles.YoucanusetheAddbuttontoaddnewtilelayers,eachwithadifferentdepth.Negativedepthscanbeusedtoputtilesinfrontofinstances.Ifyoualsogiveobjectsdifferentdepthsyoucanputthembetweendifferenttilelayers.IfyoupressDeleteyoudeleteatilelayertogetherwithallitstiles.(Theremustalwaysbeatleastonelayer.)IfyoupressChangeyoucanchangethedepthofatilelayer.Ifyougiveitthesamedepthasanotherlayer,thelayersaremerged.

Usingtilesisapowerfulfeaturethatshouldbeusedasmuchaspossible.Itismuchfasterthanusingobjectsandthetileimagesarestoredonlyonce.Soyoucanuselargetiledroomswithverylittlememoryconsumption.

Views

Finally,thereisatablabeledviews.Thisgivesamechanismfordrawingdifferentpartsofyourroomatdifferentplacesonthescreen.Therearemanyusesforviews.Firstofall,inanumberofgamesyouwanttoshowonlypartoftheroomatanytime.Forexample,inmostplatformgames,theviewfollowsthemaincharacter.Intwo-playergamesyouoftenwantasplit-screenmodeinwhichinonepartofthescreenyouseeoneplayerandinanotherpartyouseetheotherplayer.Athirduseisingamesinwhichpartoftheroomshouldscroll(e.g.withthemaincharacter)whileanotherpartisfixed(forexamplesomestatuspanel).ThiscanallbeeasilyachievedinGameMaker.

Whenyouclickthetablabeledviewsthefollowinginformationwillshow:

AtthetopthereisaboxlabeledEnabletheuseofViews.Youmustcheckthisboxtouseviews.Belowthisyouseethelistofatmosteightviewsyoucandefine.Belowthelistyoucangiveinformationfortheviews.Firstofallyoumustindicatewhethertheviewshouldbevisiblewhentheroomstarts.Makesureatleastoneviewisvisible.Visibleviewsareshowninbold.

Aviewisdefinedbyarectangularareaintheroom.Thisistheareathatmustbeshownintheview.Youspecifythepositionofthetop-leftcornerandthewidthandheightofthisarea.Secondly,youmustspecifywherethisareaisshowninthewindowonthescreen.Thisiscalledthe(view)port.Againyouspecifythepositionofthetop-leftcornerandthesize.Ifyouhaveasingleviewthepositionistypically(0,0).Notethatthesizeoftheportcanbedifferentfromthesizeoftheview.Inthiscasetheviewwillbescaledtofitintheport.(Incodeitisalsopossibletorotateaview.)Theportscanoverlap.Inthiscasethearedrawnintheindicatedorderontopofeachother.

Asindicatedabove,youoftenwanttheviewtofollowacertainobject.Thisobjectyoucanindicateatthebottom.Iftherearemultipleinstancesofthisobject,onlythefirstoneisfollowedbytheview.(Incodeyoucanalsoindicatethataparticularinstancemustbefollowed.)Normallythecharactershouldbeabletowalkaroundabitwithouttheviewchanging.Onlywhenthecharactergetsclosetotheboundaryoftheview,shouldtheviewchange.Youcanspecifythesizeoftheborderthatmustremainvisiblearoundtheobject.Finally,youcanrestrictthespeedwithwhichtheviewchanges.Thismightmeanthatthecharactercanwalkoffthescreen,butitgivesamuchsmoothergameplay.Use-1ifyouwanttheviewtochangeinstantaneously.

Fonts

WhenyouwanttodrawtextinyourgamethistextisdrawninanArial12pointsfont.Tomakemorefancylookingtextsyouprobablywanttousedifferentfonts.Tousedifferentfontsyoumustcreatefontresources.Ineachfontresourceyouspecifyaparticulartypeoffontwhichcanthenbeusedinyourgameusingtheactiontosetafont.

Tocreateafontresourceinyourgame,usetheitemCreateFontintheResourcesmenuorusethecorrespondingbuttononthetoolbar.Thefollowingformwillpopup.

Asalwaysyoushouldgiveyourfontresourceaname.Nextyoucanpickthenameofthefont.Alsoyoucanindicateitssizeandwhetheritshouldbeboldand/oritalic.Realizethatlargefontstakealotofmemorytostore.Soyouarestronglyrecommendednottousefontswithasizelargerthansay32.(Itispossibletoscalethefontswhilerunningthegame.)Anexampleoftheindicatedfontisshownatthebottom.

Afonttypicallyconsistof256characters,numberedfrom0to255.Butingeneralyouuseonlyasmallportionofthese.Sodefaultinafontonlythecharactersfrom32till127arestoredinthefont.Themorecharacters

youstoreinthefontthemorememoryitwilluse.Youcanchangethecharacterrangeused.ToseetheindexofeachcharacteryoucanusetheCharacterMapthatcanbefoundintheWindowsStartmenuunderAccessories/SystemTools.Somestandardrangescanbeindicatedusingthebuttons:TheNormalrangefrom32till127,theAllrangefrom0till255,theDigitsrangethatonlycontainsthe10digits,andtheLettersrangethatcontainsalluppercaseandlowercaseletters.Otherrangescanbeusedbytypinginthefirstandlastcharacterindex.Ifacharacterdoesnotlieintherangeitisreplacedbyaspace.

Normallyyouhavealargenumberofdifferentfontsinstalledonyourcomputerandtherearewebsiteswhereyoucandownloadhundredsmore.Theproblemisthatifyouusetheminyourgameandthengiveyourgametosomebodyelsetoplaythereisabigchancethattheotherpersondoesnothavethesamefontsinstalledonhisorhercomputer.Toavoidthis,GameMakerembedsallthefontsyouwanttouseinthegamefile,butonlyinthestand-alonegames.Soifyougiveastand-alonegametosomeoneelseyoudon'tneedtoprovidethefontfiles.Butifyougivesomebodytheeditableversionofyourgameandyouusefancyfonts,youbetteralsoprovidethepersonwiththecorrectfontfiles.

Paths

Inmoreadvancedgamesyouoftenwanttoletinstancesfollowcertainpaths.Eventhoughyoucanindicatethisbye.g.usingtimereventsorcode,thisisrathercomplicated.Pathresourcesareaneasiermechanismforthis.Theideaisrathersimple.Youdefineapathbydrawingit.Nextyoucanplaceanactioninthecreationeventoftheobjecttotelltheobjecttofollowtheparticularpath.Thischapterwillexplainthisindetail.

Definingpaths

Tocreateapathinyourgame,chooseCreatePathfromtheResourcesmenu.Thefollowingformwillpopup(intheexamplewealreadyaddedalittlepath).

Atthetopleftoftheformyoucansetthenameofthepath,asusual.Belowityoufindthepointsthatdefinethepath.Eachpointhasbothapositionandaspeed(indicatedwithsp).Dependingonhowyouusethepath,thepositioniseitherabsolute,thatis,theinstanceforwhichyouwill

laterusethepathwillfollowitatthatparticularplace,oritisrelative,thatis,theinstancewillalwaysstartatthefirstpositiononthepathandfollowthepathfromthere.Thespeedshouldbeinterpretedasfollows.Avalueof100meanstheoriginalspeedgivenforthepathwhenassigningittotheinstance.Alowervaluereducesthespeed,ahighervalueincreasesit(soitindicatesthepercentageoftheactualspeed).Speedwillbeinterpolatedbetweenpoints,sothespeedchangesgradually.

ToaddapointpressthebuttonAdd.Acopyismadeofthecurrentlyselectedpoint.Nowyoucanchangetheactualpositionandspeedbychangingthevaluesintheeditboxes.Wheneveryouselectapointinthelist,youcanalsochangeitsvalues.PressInserttoinsertanewpointbeforethecurrentone,andDeletetodeletethecurrentpoint.

Attherightoftheformyouwillseetheactualpath.Thereddotindicatesthecurrentlyselectedcontrolpoint.Thebluedotsaretheothercontrolpoints.Thegreensquareindicatesthepositionwherethepathstarts.Youcanalsochangethepathusingthemouse.Clickanywhereontheimagetoaddapoint.Clickonanexistingpointanddragittochangeitsposition.Whenyouhold<Shift>whileclickingonapoint,youinsertapoint.Finally,youcanusetherightmousebuttontoremovepoints.(Notethatyoucannotchangethespeedthisway.)Normallythepointswillbealignedwithagrid.Youcanchangethegridsettingsatthetoptoolbar.Hereyoucanalsoindicatewhetherthegridshouldbevisibleornot.Ifyouwanttopreciselypositionapoint,holdthe<Alt>keywhileaddingormovingit.

Youcaninfluencetheshapeofthepathintwoways.Fistofallyoucanusethetypeofconnection.Youcaneitherchoosestraightlineconnectionsorasmoothpath.Secondly,youcanindicatewhetherthepathmustbeclosedornot.

Onthetoolbarthereareanumberofimportantcontrols.Fromlefttorighttheyhavethefollowingmeaning.Thefirstbuttonindicatesthatyouarereadyandwanttoclosetheform,keepingthechanges.(Ifyouwanttodiscardthechanges,pressthecrosstoclosethewindowandindicatethatyoudonotwanttosavethechanges.)Nextthereisthebuttontoundothelastchange.

Thefollowingsetoftoolbarbuttonsallowsyoutheclearthepath,reversetheorderinwhichthepathistraversed,shiftthepath,mirrorithorizontally,flipitvertically,rotateit,andscaleit.Nexttherearebuttonstoshifttheview(notthepathitself;theactualviewareaisindicatedinthestatusbaratthebottom)andtocentertheview.

Asalreadyindicatedaboveyoucannextsetthesnapvaluesandwhethertoshowthegrid.Finallythereisabuttontoindicatethatyouwanttoseeaparticularroomasbackgroundforthepath.Usingthisyoucaneasilyputthepathataparticularplaceintheroom,forexampleonaracetrack,sothatlatertheinstanceswillfollowthecorrectroute.(Thisonlymakessensewhenyouuseabsolutepaths;seebelow.)

Assigningpathstoobjects

Toassignapathtoaninstanceofanobject,youcanplacethepathactioninsomeevent,forexampleinthecreationevent.Inthisactionyoumustspecifythepathfromthedropdownmenu.Therearesomefurthervaluesyoucanprovide.

Youmustindicatethepaththatmustbefollowedandthespeedinpixelsperstep.Whenthespeedispositivetheinstancestartsatthebeginningofthepath.Ifitisnegativeitstartsattheend.Rememberthatwhenyoudefinedthepathyouspecifytheactualspeedrelativetothisindicatedspeed.Thereisalsoanactiontochangethespeedwithwhichthepathisexecuted.Youcould,forexample,usethistoletaninstanceslowdownorspeedupalongitspath.Notethatthenormalspeedoftheinstanceisignored(actuallysetto0)whenexecutingapath.Alsothingslikegravityandfrictiondonotinfluencethemotionalongapath.

Nextyouspecifytheendbehavior,thatis,whatshouldhappenwhentheendofthepathisreached.Youcanchoosetostopthemotionandendthepath.Youcanalsorestartthepathfromthebeginning,thatis,theinstancejumpsbacktothepositionwherethepathwasstartedandexecutesthepathagain.Athirdoptionistorestartfromthecurrentposition,thatis,theinstancefollowsthepathagainbutnowwiththisnewstartingposition(thisisthesamewhenthepathisclosed).Finallyyou

canchoosetoreversethemotion,makingtheinstancegobackandforthalongthepath.Notethatalsoattheendofthepathaneventhappens;seebelow.

Finallyyoucanindicatewhetherthepathmustbeabsoluteorrelative.Anabsolutepathisexecutedattheplacewhereitisdefined.Theinstanceisplacedatthestartpositionandmovedfromthere(endpositionwhenspeedisnegative).Thisis,forexample,usefulwhenyouhavearacetrackonwhichyouhavedefinedthepath.Whenyouchooserelativetheinstancesstartsexecutingthepathfromitscurrentposition.Thisisusefulwhenaninstanceshouldmakealocalmotion.Forexample,spaceshipsinaspaceinvadergamecanmakeaparticularturnfromtheircurrentposition.

Whenyouwanttoplacetheinstanceatadifferentpointalongitspathyoucanusetheactiontosetthepathposition.Apathpositionalwaysliesbetween0and1,0indicatingthestartpositionand1theendpositiononthepath.Notethatineachstepthedirectionvariableisautomaticallysettothecorrectdirectionalongthepath.Youcanusethisvariabletochoosethecorrectorientationforthesprite.

Whenusingscriptsorpiecesofcodeyouhavemorecontroloverthewaythepathisexecuted.Thereisafunctiontostartapathforaninstance.Thevariablepath_positionindicatesthecurrentpositiononthepath(between0and1asindicatedabove).Thevariablepath_speedindicatesthespeedalongthepath.Avariablepath_scalecanbeusedtoscalethepath.Avalueof1istheoriginalsize.Alargervalueindicatesthatthepathismadelarger;asmallervaluemakesitsmaller.Thevariablepath_orientationindicatestheorientationinwhichthepathisexecuted(indegreescounter-clockwise).Thisenablesyoutoexecutethepathinadifferentorientation(e.g.movingupanddownratherthanleftandright).Thereisalsoavariabletocontroltheendbehavior.Finallytherearelotsoffunctionstoaskforpropertiesofpaths(e.g.thexandycoordinateatacertainpositions)andtherearefunctionstocreatepaths.Thereareevenfunctionsthatcreatecollisionfreepathsforaninstancetoreachacertaingoal.SeethelatersectionsonGMLfordetailsonthis.

Youmightwonderwhathappenswhentheinstancecollideswithanother

instancewhileitfollowsapath.Basicallythesamehappensaswhentheinstancemoveswithaspeed.Whenthereisasolidinstance,theinstanceisplacedbackatitspreviouslocation.WhenbothinstancesarenotsolidtheyareplacedattheirnewpositionsNextthecollisionevent(s)areexecutedanditischeckedwhetherthecollisionhasbeenresolved.Ifnotandtheotherinstanceissolidtheinstancewillstop,asitshould(assumingthereisacollisioneventdefined).Also,thepath_positionvariableisnotincreased.Whentheblockinginstancedisappearstheinstancewillcontinuetofollowitspath.Tohandlecollisionsyourselfthevariablepath_positionpreviouscanbeuseful.Itholdsthepreviouspositionforthepathandyoucansetthepathpositiontothisvariabletoavoidadvancingalongthepath.

Thepathevent

Asdescribedabove,youcanindicatewhatmusthappenwhentheinstancereachestheendofthepath.AtthismomentalsoanEndofPatheventoccurs.YoucanfinditundertheOtherevents.Hereyoucanplaceactions.Forexample,youmightwanttodestroytheinstance,orletitstartanew(different)path.

Timelines

Inmanygamescertainthingsmusthappenatcertainmomentsintime.Youcantrytoachievethisbyusingalarmeventsbutwhenthingsgettoocomplicatedthiswon'tworkanymore.Thetimelineresourceismeantforthis.Inatimelineyouspecifywhichactionsmusthappenatcertainmomentsintime.Youcanusealltheactionsthatarealsoavailableforthedifferentevents.Onceyoucreateatimelineyoucanassignittoaninstanceofanobject.Thisinstancewillthenexecutetheactionsattheindicatedmomentsoftime.Letusexplainthiswithanexample.Assumeyouwanttomakeaguard.Thisguardshouldmove20timestepstotheleft,then10upwards,20totheright,10downwardsandthenstop.Toachievethisyoumakeatimelinewhereyoustartwithsettingamotiontotheleft.Atmoment20yousetamotionupward,atmoment30amotiontotheright,atmoment50amotiondownwardsandatmoment60youstopthemotion.Nowyoucanassignthistimelinetotheguardandtheguardwilldoexactlywhatyouplanned.Youcanalsouseatimelinetocontrolyourgamemoreglobally.Createaninvisiblecontrollerobject,createatimelinethatatcertainmomentscreatesenemies,andassignittothecontrollerobject.Ifyoustarttoworkwithityouwillfindoutitisaverypowerfulconcept.

Tocreateatimeline,chooseCreateTimeLinefromtheResourcesmenu.Thefollowingformwillpopup.

Itlooksabitliketheobjectpropertiesform.Attheleftyoucansetthenameandtherearebuttonstoaddandmodifymomentsinthetimeline.Nextthereisthelistofmoments.Thislistspecifiesthemomentsintimestepsatwhichassignedaction(s)willhappen.Thenthereisthefamiliarlistofactionsfortheselectedmomentandfinallythereisthetotalsetofactionsavailable.Attheleftyoucanusethefollowingbuttons:

Add.Usethistoaddamomenttothetimeline.Youmustindicatethemoment,whichisthenumberofstepssincethetimelinewasstarted.Nowyoucandragactionstothelistasforobjectevents.Change.Usethisbuttontochangethetimestepsforthecurrentlyselectedmoment.Delete.Usethisbuttontodeleteamomentorarangeofmoments.Youmustindicatethetimestepofthefirstmomenttodeleteandthelastone.Allmomentsinbetweenwillbedeleted.Clear.Usethisbuttontocleartheentirelistofmoments.Shift.Usethisbuttontoshiftarangeofmomenttoanewmoment.Youmustindicatethestartoftherange,theendoftherange,andthenewtimesteptowhichthestartoftherangemustbeshifted.Whendifferentmomentsbecomethesametheiractionlistswillbemerged.Duplicate.Thisisalmostthesameastheshiftbuttonbutinthiscaseacopyofthemomentsaremade.Spread.Usethisbuttontospreadoutarangeofmomentsbyaddingtimebetweenthemorputthemclosertogetherbyremovingtime

betweenthem.Youspecifythestartandtheendoftherangeandthepercentageforthespread.Apercentageof100meansnothingchanges.Forvaluessmallerthan100themomentsaremovedclosertogetherandforvalueslargerthan100theyaremovedfurtherapart.Forexampleifyouhavemomentsattimesteps5,8,and12andyouindicateasrange5:12andapercentage200,themomentswillmovetotimesteps5,11,and19.(Theintervalsbetweenthemhavedoubled.)Whendifferentmomentsbecomethesametheiractionlistswillbemerged.Merge.Usethisbuttontomergeanumberofmomentsintoasingleone.Youspecifythestartandtheendoftherangeandtheywillallbemergedintothestartmoment.

Makesureyoudonotcreatenegativetimemoments.Theywillneverbeexecuted.

ThereisalsoabuttonShowInformationthatshowsthetimelineinareadableform.

Thereareanumberofactionsrelatedtotimelines.YoucanfindtheminthesectiononMoreMainActions.

Scripts

GameMakerhasabuilt-inprogramminglanguagecalledGML.OnceyoubecomemorefamiliarwithGameMakerandwanttouseittoitsfullestextend,itisadvisabletostartlearningtousethislanguage.FormoredetailsintheGMLlanguageseePart4ofthisdocumentation.

Therearetwowaystousethelanguage.Firstofallyoucancreatescripts.Thesearepiecesofcodetowhichyougiveaname.Theyareshownintheresourcetreeandcanbesavedtoafileandloadedfromafile.TheycanevenbeusedtoformalibrarythatextendsthepossibilitiesofGameMaker.Alternatively,youcanaddacodeactiontosomeeventandtypeapieceofcodethere.Addingcodeactionsworksinexactlythesamewayasaddingscriptsexceptfortwodifferences.Codeactionsdon'thaveanameandcannotusearguments.Alsotheyhavethewell-knownfieldtoindicatetowhatobjectstheactionshouldapply.Fortherestyouentercodeinexactlythesamewayasinscripts.WerecommendyoutousescriptsforallbutsimplepiecesofcodeasGameMakerhasmanymorefeaturesthatdealwithscripts.Sowefurtherconcentrateonscriptsinthischapter.

Asstatedbefore,ascriptiswrittenwithcodeinGML(thebuilt-inprogramminglanguage)andismeanttoperformaparticulartask.Scriptscantakesinput-variablescalledarguments(sometimescalledparameters).Toexecuteascriptfromanyevent,youcanusethescriptaction.Inthescriptactionyouspecifythescriptyouwanttoexecute,togetherwiththeuptofivearguments.

Youcanalsoexecuteascriptfromwithinapieceofcode(adifferentscript)inthesamewayyoucallaGM-function.Inthatcaseyoucanuseupto16arguments.Scriptscanreturnavalue.Thisisoftenusedtobuildcalculatingmethods(mathematicalmethods).Thereturnkeywordisusedforthis.Nocodeafterthereturnkeywordisexecuted!Whenascriptreturnsavalue,youcanalsouseitasafunctionwhenprovidingvaluesinotheractions.

ScriptsareextremelyusefultoextendthepossibilitiesofGameMaker.Thisdoesthoughrequirethatyoudesignyourscriptscarefully.Scriptscanbestoredinfilesthatcanbeaddedtoyourgame.Toimportascriptfile,usetheitemImportscriptsfromtheScriptsmenu.TosaveyourscriptsintheformofafileuseExportscripts.Scriptlibrariesaresimpletextfiles(althoughtheyhavetheextension.gml).Preferablydon'teditthemdirectlybecausetheyhaveaspecialstructure.

Tocreateascriptinyourgame,chooseCreateScriptfromtheResourcesmenu.Acodeeditorwillappearthatwillbedescribednext.

Thecodeeditor

Whencreatingoreditingascript(oracodeaction)thefollowingcodeeditorformwillappear(intheexamplewealreadyaddedalittlescriptthatcomputedtheproductofthetwoarguments).

Atthetoprightyoucanindicatethenameofthescript.Youshouldgiveallofyourscriptsasensiblename.Makesurethenameonlyconsistsofletter,digits,andthe_symbol.Itshouldnotstartwithadigit.Inthiswayyoucanusethescriptlaterasafunctionincode.

Atthetopyouhaveatoolbarwithsomeusefulbuttons.Fromlefttoright

youhavetheOKbuttontoclosetheeditor,savingthechanges,buttonstoloadthescriptfromatextfile,saveittoatextfile,andprintit.

Nextthereareundoandredobuttons.Theeditorwillbasicallyrememberallchangesyoudidandyoucanundothem(orredotheundonechanges).YoucanchangethemaximalnumberofundooperationsinthePreferences.Hereyoucanalsoindicatewhetheryouwanttogrouptheundooperations(suchthate.g.typingalineoftextcanbeundoneinonestep)orthateverykeystrokeisseparatesaved.Youcanuse<Ctrl>+Zforundoand<Ctrl>+<Shift>+Zforredo.

Nexttothistherearebuttonstocut,copy,andpastetext,asyoushouldbefamiliarwith.Thefinaltwobuttonsareforfindingandreplacingandforcodechecking.Thesewillbeexplainedbelowindetail.

Belowthetoolbarthereistheareawhereyoucantypethetext.Atthelefttherearethelinenumbers.(YoucanswitchtheseonandoffusingtheF9key.)Thelinewiththecursoronitismarkedinbold.Thedarkredbarbehindcertainlinenumbersindicatedthattheselineshavechanged.Youwillnoticethatyoucantypetextanywhereonthelines.Soalinedoesnotreallyhaveanend.Thistendstobeusefulwhenalligningtext.Therearemanyeditingpossibilities,thatwillbedescribedbelow.

Atthebottomthereisthestatusbar.Thisshowsfromlefttorightthecurrentlinenumber,totalnumberoflinesandcursorposition.WhetheryouareinInsertmodeorOverwritemode.(InOverwritemodealsothecursorchnangestomakeitclearthatyouareoverwritingtheexistingtext.)Nextthereisthepointsizeforthefontused.YoucanuseF7andF8todecreaseorincreasethefontsize.(YouhavemorecontroloverthefontsizeandtypeinthePreference.)

Editingtools

Theeditorhasmanyeditingpossibilities.Someofthesecanalsobeaccessedthroughthepop-upmenuthatappearswhenyoupresstherightmousebutton.Herearethemostimportantones:

MultipleundoandredoeitherperkeypressoringroupsThearrowkeysmoveyouaroundinthetext.Use<Ctrl>withtheleftandrightarrowkeytomovetothebeginningofthepreviousornextword.Use<Ctrl>withtheupanddownkeytoalsoscrollthetext.Holdthe<Shift>keytoselecttext.Doubleclickthelinenumbertoselectthecompleteline.TheHomekeymovestothebeginningofthelineandtheEndkeytotheendoftheline.With<Ctrl>theymovetothestartandendofthescript.Holdthe<Shift>keytoselecttext.Youcanscrollthroughthetextwiththemousewheel.With<Ctrl>thecursorscrollswiththetext.Holdthe<Shift>keytoselecttext.Intelligentautoindentthatalignswiththepreviouslinewhenyouusethereturnkeyofthebackspacekey(canbesetinthepreferences).Intelligenttabbingthattabstillthefirstnonspaceinthepreviouslines(canbesetinthepreferences).Use<Ctrl>+Itoindentselectedlinesand<Shift>+<Ctrl>+Itounindentselectedlines.Hold<Ctrl>withtheBackspaceorDeletekeytodeleteuntilthebeginningofthepreviousornextword.Youcandragaselectionwiththemouse.(Use<Ctrl>tocopyit.)Thenewlocationisimmediatelyshown.Cut,copyandpasteoftextbetweenscriptformsandotherprograms.UseF12toopenthescriptorresourcewhosenameisatthecursorposition.

Colorcoding

Asyoumighthavenoticed,partsofthescripttextarecolored.Theeditorknowsaboutexistingobjects,built-invariablesandfunctions,etc.Color-codinghelpsalotinavoidingmistakes.Inparticular,youseeimmediatelyifyoumisspelledsomenameoruseakeywordasavariable.Ifyoudon'tlikethecolorcoding,inthePreferencesyoucanswitchitonandoff(youcanalsouseF10).InthePreferencesyoucanalsochangethecolorforthedifferentcomponentsofthecode.

Functionandvariablehelp

GameMakercontainsmanybuilt-infunctionsandvariablesandyouaddyourownresourcesandscriptstothis.Soitmightbehardtorememberallofthem.Fortunatelytheeditorhelpsyouwiththis.Whenyoutypepartofaname(atleasttwocharacters)andwaitalittle,alistisshownofallpossibilities.Forexample,asfollows:

Youcancontinuetypingandthelistwilladapt.YoucanusetheupanddownkeystoscrollthroughthelistandpressEntertoreplacethetextyouaretypingwiththeselectedfunctionorvariablename.

Youcanswitchthisfeatureonandoffinthepreferences.Youcanalwaysforcethelisttoappearbypressing<Ctrl>+Space.

Asecondformofhelpisgivenwhenyouaretypingintheargumentsforafunction.Inthiscase,inthestatusbaratthebottomthefunctionwithitsargumentsisgiven.Thecurrentargumentyouaretypingisshowninbold.Inthiswayyouwillneverforgetargumentsorgettheorderwrong.

Findandreplace

Itiscommonthatyouwanttofindsomepieceoftextinyourcodeorreplacesometextwithanotherone.TothisendpresstheFindbuttoninthetoolbar.Apanelwillshowupattherightoftheform,asfollows:

Youcantypethefindstringatthetop.Notethatinthecodealloccurrencesofthefindstringareimmediatelyshownwithayellowbackground.(YoucanswitchthisoffinthePreferences.)Asusualyoucanindicatewhetherthesearchmustbecasesensitive(whichisnormallywhatyouwantasvariableandfunctionnamesinGMLarealsocasesensitive)andwhetheryouwanttoonlysearchforwholewords.Notethattheeditorremembersyourmostrecentsearches.

Withthebuttonswiththebluearrowsyoucannowmovetotheprevious,next,first,andlastoccurrenceofthefindstring.Itwillbeselectedinthetextsuchthatyoucane.g.deleteit.

Whenyouwanttoreplaceoccurrences,alsotypeatextinthereplacebox.Nowyoucanusethebuttonstoreplacethepreviousoccurrence,thenext,thefirst,thelast,oralloccurrencesofthefindtext.RememberyoucanalwaysuseUndotoundothereplacements.

Codesnippets

Codesnippetsaresmallpiecesofcodethatyouwilloftenuse.Youcanaddtheminthecodethroughthesnippetmenu.TothisendpressF2.Amenuappearsfromwhichyoucanselectthesnippet.Itwillbeinsertedatthecursorinyourcode.Somepiecesconsistsofcapitallettersonly.

Thesemuststillbereplacedbyyou.Thefirstoneisselectedforreplacement.Toreplaceanother,simplydoubleclickonit.

Youcandefineyourowncodesnippetsifyouwant.Thesnippetsarestoredinthefilesnippets.txtinthefolderinwhichGameMakerisinstalled.Youcaneditthisfilewithanytexteditor.Eachsnippetisonaseparatelineandthereshouldbenoblanklines.Itstartswiththenameofthesnippet(showninthemenu)followedbythecolon(:)followedbytheactualsnippet.Use#foranewlineandputthetextthatneedstobeselectedfirstbetween|symbols.Seetheexamplesthatarealreadyinthefile.(Bettermakeabackupofitbeforeyoustartchangingit.)

Errorchecking

Inthetoolbaratthetopthereisabuttonwithwhichyoucanswitcherrorcheckingonoroff.Whenerrorcheckingison,GameMakerconstantlyteststhecodeyouaretypingandreportsthefirsterroritfindsatthebottomofthewindow.Alsothelinenumberforthelinewiththeerrorisdrawninred.Youcanclickontheerrormessagetogotothecorrectlineandpositiontocorrecttheerror.Notethatnotallaspectscanbetestedatthisstagebutthesyntaxofyourscriptwillbetested,togetherwiththeexistenceoffunctionsused.

Whenyoustarttypingascript,errorcheckingmightbeannoyingsoyoucanswitchitoff.Butwhenthescriptisalmostreadyyoubetterswitchitontocorrectalltheerrors.Notethatalsothecolorcodingwillhelpyoucatcherrors.Finally,whenyouputyourcursoratabrackettheeditorwillshowyouthecorrespondingopeningorclosingbracket.Ifitcannotfindit,itisshowninred.(YoucanswitchthisoffinthePreferences.)

Debugging

Whencreatingscriptsyoucaneasilymakemistakes.Alwaystestthescriptsbyusingtheerrorcheckingbutton.However,thiswillnotcatchallerrors.Soyouwillneedtorunthegametotestyourcode.

Whenanerroroccursduringtheexecutionofascriptthisisreported,withanindicationofthetypeoferror,thescriptoractionitoccursin,andthelineandposition.Rarelyyouwillseeapopupwiththetext"Unexpectederroroccurredduringthegame".Thiserrormessageindicatethatsomeproblemoccurredinwindowsorinthehardware.Oftenthereasonforthisisinfiniterecursion,lackofmemoryorinsufficienthardware,driversorfirmware.Generallyspeaking,theseerrorshavetodowithproblemsoutsidetheGameMakerenvironment.

Ifyouneedtocheckthingsmorecarefully,youcanrunthegameindebugmode.Nowaformappearsinwhichyoucanmonitorlotsofinformationinyourgame.

UndertheRunmenuyoucanpausethegame,runitstepbystepandevenrestartit.UndertheWatchmenuyoucanwatchthevalueofcertainexpressions.UseAddtotypeinsomeexpressionwhosevalueisshownineachstepofthegame.Inthiswayyoucanseewhetheryourgameisdoingthingstherightway.Youcanwatchmanyexpressions.Youcansavethemforlateruse(e.g.afteryoumadeacorrectiontothegame).UndertheToolsmenuyoufinditemstoseeevenmoreinformation.Youcanseealistofallinstancesinthegame,youcanwatchallglobalvariables(well,themostimportantones)andthelocalvariablesofaninstance(eitherusetheobjectnameortheidoftheinstance).Youcanalsoviewmessageswhichyoucansendfromyourcodeusingthefunctionshow_debug_message(str).Finallyyoucangivethegame

commandsandchangethespeedofthegame.Ifyoumakecomplicatedgamesyoushouldreallylearnhowtousethedebugoptions.

ExtensionPackages


ExtensionpackagesextendthepossibilitiesofGameMaker.AnextensionpackagecanaddasetofactionstoGameMakeroritaddsanumberofadditionalfunctionsandconstantstotheGMLlanguagebuiltintoGameMaker.Whenextensionpackagesareavailabletoyou,helpabouttheseisplacedintheHelpmenu.

WhendoubleclickingontheExtensionPackagesresourceitemthefollowingformisshown:

Inthisformyoucanindicatewhichextensionpackagesmustbeusedinthegame.OntheleftthereisthelistofUsedpackagesandontherightisthelistofAvailablepackages.Tomoveapackagefromonelisttotheother,simplyselectitandpressthebuttonbetweenthelist.Whenselectingapackageashortdescriptionisgivenatthebottom.FurtherhelpisavailablebypressingtheHelpbutton.

ExtensionpackagesareanextremelypowerfulpartofGameMaker.AfewextensionpackagesareprovidedwithGameMakerbutmanymorewillbecomeavailablethroughthewebsite.Toinstallnewpackagesoruninstallexistingones,presstheInstallbutton.Thefollowingformisshown

Youwillseealistofallextensionpackagesinstalled.ByselectingapackageandclickingtheUninstallbuttonthepackageisremovedfromthesystem.

Installpackagesaredistributedintheformofa.gexfile.YoucanfindanumberofsuchpackagesonourwebsitewhichyoucangotobypressingthebuttonFindMore.Onceyoudonwloadedsuchapackagefileonyourcomputer,presstheInstallbuttonandselectthepackagefile.Itwillthenbeinstalledinthesystem.

Ifyouwanttocreateyourownextensionpackages,pleasecheckouttheinformationthatisavailableonhttp://www.yoyogames.com/extensions.

http://www.yoyogames.com/extensions

Exportingandimportingresources


Note:Importandexportofresourcesisonlyforexperiencedusers.Carefullyreadthissectionbeforeusingthesefeatures.Also,alwaysmakeaback-upcopyofyourgamebeforeimportingresources.

Sometimesyouwanttocopycertainresources(sprites,sounds,rooms,etc.)fromonegametoanothergame.Forexamplewhenyouwanttocreateanewgameusingthesamespritesandsoundsasanothergame.Orwhenyouareworkingtogetheronagame.Oneofyoumighthavecreatedsomeadditionalroomsthatyouthenwanttoimportintheothergame.TothisendGameMakerhascommandstoimportandexportresources.

Exportingresources

Toexportresources,chooseExportResourcesfromtheFilemenu.Firstofallitischeckedwhetherallresourceshavedifferentnames.Becauseresourcesinonegamearelinkedtotheonesintheothergamebyname,itisessentialthatallresourceshavedifferentnames.Ifnot,yougetanerrormessageandnoresourcescanbeexported.Otherwise,afileselectorisshowninwhichyoucanindicatethenameofthefileinwhichyouwanttoexporttheresources.Thesefilesmustendwiththeextension.gmres.Nextthefollowingformisshown:

Inthisformyoucanindicatewhichresourcesmustbeexported.Defaultallareexportedbutyoucanselecttheparticulartypesofresourcesyouwanttoexport.Caremustbetakenwhenexportingobjects,timelines,orrooms.Thesewillrefertosprites,sounds,triggers,etc.Soifyoudonotexporttheseotherresourcesaswellyoumustbecertainthattheseotherresourcesalreadyexistinthegameinwhichyouaregoingtoimporttheresources(underthesamenames).Ifyouareuncertain,betterexporteverything.

Importingresources

OnceyouhaveafilecontainingresourcesyoucanimporttheminadifferentgamebychoosingImportResourcesfromtheFilemenu.Firstofallitischeckedwhetherallresourceshavedifferentnames.Again,becauseresourcesinonegamearelinkedtotheonesintheothergamebyname,itisessentialthatallresourceshavedifferentnames.Ifnot,yougetanerrormessageandnoresourcescanbeimported.Otherwise,afileselectorisshowninwhichyoucanindicatethenameofthefilefromwhichyouwanttoimporttheresources.Thesefileswillendwiththeextension.gmres.Nextallopenpropertyformsareclosed.Thisisnecessarybecauseimportedresourcesmightreplaceexistingones.Nextthefollowingformisshown:

Alltypesofresourcesinthefileareshown.(Theonesthatwerenotexportedandgrayedout.)Youcanselectwhichoftheseresourcesyouwanttoimport.Mostofthetimeyouwanttoimportallbutsometimesyouwanttomakeaselection.Becarefulwhenimportingobjects,rooms,ortimelineswhilenotimportingotherresources.Asindicatedabovethiscanleadtoproblemsiftheresourcestheyrefertodonotexistinyourgameunderthesamename.Insuchacasetheywillbereplacedbynon-existingresources.(Forexample,intheroomsitmeansthecorrespondinginstanceswillberemoved.)

Whenresourcesinthefilehavethesamenameasresourcesinthegameanamingconflictappears.Youcanindicatehowthatshouldberesolved.Thedefaultisthatyoukeeptheresourcethatwaschangedlast.Youcanhoweveralsochoosetoalwayskeeptheoriginalinthegameoralwaysreplaceitwiththeresourceinthefile.Afourthoptionistokeepboth.Onlyusethiswhenitisabsolutelynecessary,becauseyouwillnowendupwithmultipleresourceswiththesamenamewhichcanleadtoconflictswhenreferringtothem.Whenyouimportresourcesintoanemptygame,betterchoosetoalwaysreplacethem.(Thismaysoundstrangebutforexampleotherwisetheglobalgamesettingswillnotbereplacedasthenewemptygameisofamorerecentdate!)

Finallyyoucanindicatewhethertoplacethenewresources(thatis,theonesthatdonotalreadyoccur)inanewgroup.Thismightbeusefulto

distinguish(visually)theimportedresourcesfromtheexistingones.Ifyoucheckthisboxthenewresourceswillbeplaceinagroup.Thenameofthisgroupisthenameoftheimportfile.

OnceyoupressOKtheresourcesareaddedtothegame,replacingexistingresourceswiththesamenamewhenrequired.Youwillseethemappearintheresourceselectorattheleft.

WarningsandRemarks

Importingandexportingresourcesisapowerfulmechanism,inparticularwhenyouareworkingonagamewithmultiplepeople.However,ifyoudonotunderstandwhatyouaredoingitmightleadtoerrorsandfrustration.Herearesomeimportantwarningsthatyoushouldreadandunderstand.

Alwaysmakeabackupcopyofyourgamebeforeimportingresources.Otherwiseyourhardworkmightbelost.Youcannotundotheimportofresources.Alwayscheckafteranimportwhethereverythingwasimportedcorrectly.Alsoimmediatelyrunthegametoseeifitallworks.Otherwisereturntoyourbackupcopy.Notethattheindicesofresources,instances,andtiles,mostlikelychangeintheprocesstoguaranteethattheyremainunique.Thiswillcauseproblemswhenyourefertoresources(orinstances)bynumber.Alsoitwillcauseproblemsifyouassumeanythingabouttheorderinwhichinstancesarecreated.Notethattheresourceswillbeaddedintheorderinwhichtheyaregivenintheresourcelist/tree.Newresourceswillbeaddedattheend.However,thegroupstructureismaintained.Thisisnormallywhatyouexpectbutinsomerarecasesyoumighthavetomoveresourcestoadifferentlocation.Forexample,whenyouhaveastartroom,anendroomandsomeroomsinbetween,whensomebodyaddssomerooms(inbetween)andyouthenexporttheseandimportthemintheoriginalgame,theywillappearattheend(becausetheyarenew).Youthenmustmovetheendroomtothe

appropriatelocationagain.!Notethatconstantsandtriggersonlygloballystoreinformationaboutwhentheywerelastchanged.Sowhenyouchangeoneconstantoronetrigger,allwillbereplacedwhenchoosingKeepLastChanged.Fortheglobalgamesettingsthesameholds.Theyareeitherall,ornotatallreplaced.Notethatanemptygamewillhaveanewdateatwhichitwaslastchanged.Thismeansthatifyouimportresourcesinanewemptygame,theconstants,triggers,andglobalgamesettingswillnotbeimported,unlessyousetthenameconflicthandlingtoalwaysreplace.Don'tremoveresourcesfromagamebeforeimportingthesameresourcesagain!Thismightsoundalogicalthingtodobutitwillnotwork.Onceyouremovearesourcefromagameitnolongerexists.Henceallreferencestoitwillbecomeundefined.Importingthesameresourcelaterwillnotrestorethosereferencesbecausetheprogramcannotknowitisthesameresource.Insteadlettheimportfeaturereplacetheresources.Ifyouhaveworkedonagameforalongtimeaddinganddeletingmanyresources,itisusefultocompletelyexportitandthenimportitintoanemptygame(withtheoptiontoalwaysreplace).Thegamewillworkasbeforebutwillbestrippedoflotsofunuseddata.

Polishingyourgame

Whenyouwanttodistributeyourgameyoubettermakesurethatithasalltheingredientsthatmakeitagreatgame.Besidesthegameitselfthismeansthatyoushouldprovidegameinformation,setthecorrectglobalgamesettings,andtakecareofspeed.Thissectiongivesyouinformationabouttheseaspects.

Informationonfinishingyourgamecanbefoundinthefollowingpages:

GameInformationGlobalGameSettingsSpeedConsiderations

Gameinformation

Agoodgameprovidestheplayerwithsomeinformationonhowtoplaythegame.Thisinformationisdisplayedwhentheplayerpressesthe<F1>keyduringgameplay.GameMakerhasasimplebuilt-inmechanismtoprovidegamehelp.However,itislimitedinfunctionality.Tocreatenicergamesitisbettertocreatethehelpyourselfusingspecialroomsorbyusingsplashscreenwithe.g.htmlpages.

Tocreatethesimplegameinformation,doubleclickGameInformationintheresourcetreeattheleftofthescreen.Alittlebuilt-ineditorisopenedwhereyoucaneditthegameinformation.Youcanusedifferentfonts,differentcolors,andstyles.Alsoyoucansetthebackgroundcolor.

IntheFilemenuyoucanalsosetanumberofOptions.Defaultthehelpisshowninthegamewindowandgameplayistemporarilyhalted.Hereyoucanindicatetoshowthehelpfileinaseparatewindow.Inthiscaseyoucanindicatethecaptionofthegameinformationduringthegame.Alsoyoucanindicatetheposition(use-1forcentered)andsizeofthegameinformationwindowandwhetheritshouldhaveaborderandbesizeablebytheplayer.Youcanforcetheinformationwindowtostayontopandyoucanindicatewhetherthegameshouldcontinueplayingwhile

theinformationisshown.

Goodadviceistomaketheinformationshortbutprecise.Ofcourseyoushouldaddyournamebecauseyoucreatedthegame.Allexamplegamesprovidedhaveaninformationfileaboutthegameandhowitwascreated.YoumightwanttoindicateatthebottomofthehelpfilethattheusermustpressEscapetocontinueplaying.)

Ifyouwanttomakeabitmorefancyhelp,useaprogramlikeWord.ThenselectthepartyouwantandusecopyandpastetomoveitfromWordtothegameinformationeditor.Formoreadvancedgamesthoughyouprobablywillnotusethismechanismatallbutusesomededicatedroomstoshowhelpaboutthegame.

GlobalGameSettings

Thereareanumberofsettingsyoucanchangeforyourgame.Thesechangetheshapeofthemainwindow,setsomegraphicsoptions,dealwithinteractionsettings,toloadingimage,constantsandinformationaboutthecreatorofthegame.Alsoyoucanindicateherewhichfilesshouldbeincludedinstand-alonegamesandhowerrorsshouldbehandled.

ThesettingscanbechangedbydoubleclickingonGlobalGameSettingsintheresourcetreeattheleftofthescreen.Theyaresubdividedinanumberoftabbedpages.(Someoptionsareonlyavailableinadvancedmode.)

Informationaboutthedifferentsettingscanbefoundinthefollowingpages:

GraphicsandWindowOptionsTheScreenResolutionVariousOtherOptionsLoadingOptionsErrorOptionsInformationabouttheGame

Graphicsoptions

Inthistabyoucansetanumberofoptionsthatarerelatedtothegraphicalappearanceofyourgame.Itisnormallyusefultocheckouttheeffectsoftheseoptionsbecausetheycanhaveasignificanteffectonthewaythegamelooks.Rememberthoughthatdifferentusershavedifferentmachines.Sobettermakesurethatthesettingsalsoworkonotherpeoplesmachines.

StartinfullscreenmodeWhencheckedthegamerunsinthefullscreen;otherwiseitrunsinawindow.

ScalingHereyoucanindicatewhathappenswhenthewindowislargerthantheroomorwhenthegameisruninfull-screenmode.Therearethreechoices.Youcanindicateafixedscaling.Theroomisdrawnscaledwiththegivenamountinthecenterofthewindoworthecenterofthescreen.100indicatesnoscaling.Youtypicallyusefixedscalingwhenyourspritesandroomsareverysmall.Thesecondoptionisscaletheroomsuchthatitfillsthewindoworscreenbutkeeptheaspectratio(ratiobetweenwidthandheight)thesame.Thethirdoptionistoscalesuchthatthewindoworscreeniscompletelyfilled.Thiscanleadtodistortionsintheimage(inparticularinwindowedmodewhentheusercanresizethewindow).

InterpolatecolorsbetweenpixelsWhenchecked,colorsofpixelsinsprites,backgrounds,andtilesthatarenotalignedwithpixelsonthescreenwillbeinterpolated.Thisinparticularisthecasewhentheyarescaled,rotated,orplacedatnon-integerpositions.Interpolationmakesmovementsmootherbutcanalsogiveablurredeffect.(Alsofortilesitcanleadtocracksbetweenthem,ifnotcarefullydesigned.)

ColoroutsidetheroomregionWhentheroomdoesnotcompletelyfillthewindoworscreenthereissomeareaunusedaroundit.Hereyoucanspecifythecolorofthearea.

AllowtheplayertoresizethegamewindowWhencheckedinwindowedmodetheusercanchangethesizeofthegamewindowbydraggingwiththemouseatitscorners.

LetthegamewindowalwaysstayontopWhencheckedinwindowedmodethegamewindowalwaysstaysontopofotherwindows.

Don'tdrawaborderinwindowedmodeWhencheckedinwindowedmodethegamewindowwillnothaveaborderoracaptionbar.

Don'tshowthebuttonsinthewindowcaptionWhencheckedinwindowedmodethewindowcaptionwillnotshowthebuttonstoclosethewindowortominimizeormaximizeit.

DisplaythecursorIndicateswhetheryouwantthemousepointertobevisible.Turningitoffisnormallyfasterandnicer.(YoucaneasilymakeyouowncursorobjectinGameMaker.)

FreezethegamewhentheformlosesfocusWhenchecked,whenevertheplayerbringssomeotherformtothetop(e.g.anotherapplication)thegamefreezesuntilthegamewindowagaingetsthefocus.

DisablescreensaversandpowersavingactionsWhenchecked(default)screensaversorpowersavingactions(sleep,hibernate)willnotactivatewhilethegameisrunning.Thisisimportantasthesemightdestroycertaingraphicsaspectsofthegame(likesurfaces).

Resolution

Inthistabyoucansetthescreenresolutioninwhichyourgamemustrun.Bydefaulttheresolutionisnotchanged.Butsometimesyouwanttorunthegameinalowerresolutionsoryouwanttosetthefrequencyofthemonitortomakesurethetiminginthegameworkscorrectly.IfyouwanttochangetheresolutionyoumustfirstchecktheboxlabeledSettheresolutionofthescreen.

Therearethreethingsyoucanchange.Firstofallthereisthecolordepth.Thisindicatesthenumberofbitsusedtorepresentthecolorforapixel.Mostmachinesnowonlyallowfor16-bit(HighColor)or32-bit(FullColor)butoldermachinesalsoallowedfor8-bitandsometimes24-bitcolor.GameMakeronlyworkscorrectlyin16-bitand32-bitcolor.32-bitcolorgivesnicerlookingimagesbutwilltakemorememoryandprocessingtime.Ifyouwantyourgametorunwillonmostoldermachinessetthecolordepthto16-bit.Otherwiseuse32-bitordon'tchangeit.

Secondlythereisthescreenresolution,thenumberofpixels(horizontalandvertical)onthescreen.Changingtheresolutionisusefulwhene.g.yourroomsareverysmall.Inthiscaseitmighthelptoreducetheresolutionofthescreen.Realizethoughthatthiswillalsoeffectotherapplicationsrunning.Thiscaninparticulargiveproblemswithlowresolutions.Soingeneralitisbettertoonlydothiswhenrunningthegameinfullscreenmode.GameMakerwillautomaticallychangetheresolutionbacktothestartingsituationoncethegamefinishes.

Finallyyoucanchangetherefreshfrequency.Thisindicateshowmanytimespersecondtheimageonthescreenisrefreshed.Ifyourroomspeedislargerthanthefrequencynotallstepsareactuallyvisible.Itworksbestifthefrequencyisamultipleoftheroomspeed.(Ifyouspecifyafrequencythatistoohighornotavailablethefrequencyisnotchanged.)

TherealsoisasettingheretoUsesynchronizationtoavoidtearing.

Thisrequiressomeexplanation.Adisplayisredrawnanumberoftimespersecond,dependingontherefreshfrequency.Ifaroomisdrawnhalfwaysucharefresh,thetopofthedisplaywillstillshowtheoldimagewhilethebottompartshowsthenewimage.Thisiscalledtearing.Toavoidthisyoucancheckthisoption.Inthiscasethenewroomimageisonlycopiedtothescreenwhentherefreshisnotinsidethewindowavoidingthetearingmostofthetime.Thedisadvantageisthatwenormallyhavetowaittillthenextrefresh.Thismeansthatthemaximalnumberofframesisboundedbythefrequencyofthemonitorand,whentheprocessingisnotfastenough,theframerateimmediatelydropstohalfthatnumber.Alsotherecanbeaconflictbetweentheinternaltimingofthegameandthesynchronization.Ifyouwanttodothisbestsetthemonitorfrequencytoe.g.60andalsomaketheroomspeedeither30or60.

Variousotheroptions

Hereyoucansetanumberofadditionaloptions.Firstofallyoucansetsomedefaultkeys:

Let<Esc>endthegameWhenchecked,pressingtheescapekeywillendthegame.Moreadvancedgamesnormallydon'twantthistohappenbecausetheymightwanttodosomeprocessing(likesaving)beforeendingthegame.Inthiscase,uncheckthisboxandprovideyourownactionsfortheescapekey.

Treattheclosebuttonas<Esc>keyWhencheckedtheclosebuttonofthewindowwillgenerateanescapekeyevent.Whennotcheckedtheclosebuttoneventsarecalledinstead.

Let<F1>showthegameinformationWhencheckedpressingtheF1keywilldisplaythegameinformation.

Let<F4>switchbetweenscreenmodesWhencheckedtheF4keywillswitchbetweenfullscreenandwindowedmode.

Let<F5>savethegameand<F6>loadagameWhencheckedtheplayercanuse<F5>tostorethecurrentgamesituationand<F6>toloadthelastsavedgame.(Notethatonlythebasicgamedataisstored.Onceyouuseadvancedfeatureslikeparticlesordatastructuresthosesettingsarenotsavedandyoumighthavetocreateasavemechanismyourself.

Let<F9>takeascreenshotofagameWhencheckedtheplayercanuse<F9>tocreateascreenshotofthegame.ThisscreenshotwillbeplaceinthefilescreenshotXXX.pnginthefolderwherethegameisrunning,whereXXXisthenumberofthescreenshot.Whencreatingmultiplescreenshotthenumberisautomaticallyincreased.

Alsoyoucansetthepriorityofthegameprocess.Thispriorityindicateshowmuchprocessortimeisallottedtothegame.Innormalmodetheoperatingsystemtriestogiveprocessortimetoeachprocessthatneedsitinsomereasonableway.Thehigheryouputtheprioritythemoretimeisallottedtothegame,makingitrunmoresmoothlyandfaster.Butotherprocessesgetlesstime(alsoWindowsprocessessoeventhemousemightnotmoveanymore).Usethiswithcare.

Finally,youcansettheversioninformationofthegame.Thisinformationisshowninthehelptipthatpopsupwhentheuserrestshismouseonthegameexecutable.Itisalsoshownwhentheusersclickswiththerightmousebuttonontheprogramandchoosespropertiesandthenversion.Ifyoudistributeyourgameyoubestfillinthisinformation.

Youshouldgiveyourgameaversionnumberthatconsistsoffourparts:themajorversion,theminorversion,thereleasenumberandthebuildnumber.Alsoyoushouldprovidethenameofthecompany(you),thenameoftheproduct,thecopyrightinformation,andaverybriefdescription.Allthesefieldsshouldbeatmost64characterslong.

Loadingoptions

Hereyoucanindicatewhatshouldhappenwhenloadingagame.Firstofallyoucanspecifyyourownloadingimage.Secondly,youcanindicatewhethertodisplayaloadingprogressbaratthebottomoftheimage.Youhavethreeoptionshere.Eithernoloadingbarisdisplayed,orthedefaultbarisdisplayedoryoucanspecifytwoimages:thebackgroundoftheloadingbarandtheforeground.Youcanindicatewhetherthefrontloadingbarmustbescaled(default)orclippedwhileitbecomeslonger.Inthesecondcase,makesureenoughtheimageislargeenoughtofillthebar.(Notethatbothimagesmustbespecifiedinthiscase,notjustone.)

Itispossibletoindicatethattheloadingimagemustbetransparent.Inthiscasetheleftbottompixelofthebackgroundimageisusedastransparentcolor.(Notethattransparencyfrome.g.pngorgiffilesisnottakenintoaccounthere!)Alsothealphatranslucencycanbeindicated.Avalueof0meansfullytranslucent.Avalueof255meansfullyopaque.(BothonlyworkunderWindows2000,XP,orlater.)

Secondly,youcanindicateheretheiconthatshouldbeusedforstand-alonegames.Youriconsmustcontainatleasta32x32icon,buttheycanalsocontainlargerones.Ifyoutrytoselectanothertypeoficonyouwillgetawarning.

Finallyyoucanchangetheuniquegameid.Thisidisusedforstoringthehighscorelistandsavegamefiles.Ifyoureleaseanewversionofyourgameanddon'twanttotakeovertheoldhighscorelist,youshouldchangethisnumber.

Erroroptions

Hereyoucansetanumberofoptionsthatrelatetothewayerrorsarereported.

DisplayerrormessagesWhenchecked,errormessagesareshowntotheplayer.Inthefinalversionofthegameyoumightwanttouncheckthisoption.

Writeerrormessagestofilegame_errors.logWhencheckedallerrormessagesarewrittentoafilecalledgame_errors.loginthegamefolder.

AbortonallerrormessagesNormally,certainerrorsarefatalwhileotherscanbeignored.Whencheckingthisoptionallerrorsareconsideredfatalandleadtoabortingthegame.Inthefinalversionofthegameyoudistributeyoumightwanttocheckthisoption.

Treatuninitializedvariablesas0Onecommonerroristouseavariablebeforeavalueisassignedtoit.Sometimesthisisdifficulttoavoid.Whencheckingthisoptionsuchuninitializedvariablesnolongerreportanerrorbutaretreatedasvalue0.Becarefulthough.Itmightmeanthatyoudon'tspottypingmistakesanymore.

Informationaboutthegame

Hereyoucanindicatetheauthorofthegame,theversionofthegame,andsomeinformationaboutthegame.Alsothelastchangeddateismaintained.Thisisusefulifyouareworkingwithmanypeopleonagameormakenew,updatedversion.Theinformationisnotaccessiblewhenthegameisrunning.

Speedconsiderations

Ifyouaremakingcomplicatedgamesyouprobablywanttomakethemrunasfastaspossible.EventhoughGameMakerdoesitsbesttomakegamesrunfast,alotdependsonhowyoudesignyourgame.Also,itisrathereasytomakegamesthatuselargeamountsofmemory.Inthispagewegivesomehintsonhowtomakeyourgamesfasterandsmaller.

Firstofall,lookcarefullyatthespritesandbackgroundsyouuse.Animatedspritestakealotofmemoryanddrawinglotsofspritestakesalotoftime.Somakeyourspritesassmallaspossible.Removeanyinvisibleareaaroundit(thecommandCropinthespriteeditordoesthatautomatically).Thesameappliestobackgroundimages.Ifyouhaveacoveringbackground,makesureyouswitchofftheuseofabackgroundcolor.

Ifyouusefullscreenmode,makesurethesizeoftheroom(orwindow)isneverlargerthanthescreensize.Mostgraphicscardscanefficientlyscaleimagesupbuttheyaremoreslowinscalingimagesdown!Wheneverpossible,switchoffthecursor.Itslowsdownthegraphics.

Alsobecarefulwiththeuseofmanyviews.Foreachviewtheroomisredrawn.

Besidesthegraphics,therearealsootheraspectsthatinfluencethespeed.Makesureyouhaveasfewinstancesaspossible.Inparticular,destroyinstancesoncetheyarenolongerrequired(e.g.whentheyleavetheroom).Avoidlotsofworkinthestepeventordrawingeventofinstances.Oftenthingsdonotneedtobecheckedineachstep.Interpretationofcodeisreasonablyfast,butitisinterpreted.Also,somefunctionsandactionstakealotoftime;inparticularthosethathavetocheckallinstances(likeforexamplethebounceaction).

Whenyouneedcomplicatedprocessing(forexampleforadvancedAI),youbetterwriteaDLLforthisinadifferentlanguageandcreateanextensionpackageoutofthistoimporttheDLLusingthefunctions

describedinthepageonUsingDLL's.

Thinkaboutwheretotreatthecollisionevents.Younormallyhavetwooptions.Objectsthathavenocollisioneventsaretreatedmuchfaster,sopreferablytreatcollisionsinthoseobjectsofwhichtherearejustafewinstances.

Becarefulwithusinglargesoundfiles.Theytakealotofmemoryandalsocompressbadly.Youmightwanttocheckyoursoundsandseewhetheryoucansamplethemdown.

Finally,ifyouwanttomakeagamethatmanypeoplecanplay,makesureyoutestitonanumberofdifferentmachines,inparticularalsooldermachines.

TheGameMakerLanguage(GML)

GameMakercontainsabuilt-inprogramminglanguage.Thisprogramminglanguagegivesyoumuchmoreflexibilityandcontrolthanthestandardactions.ThislanguagewewillrefertoasGML(theGameMakerLanguage).InthissectionwedescribethelanguageGMLandwegiveanoverviewofallthe(closeto1000)functionsandvariablesavailabletocontrolallaspectsofyourgame.

InformationonGMLcanbefoundinthefollowingpages:

LanguageoverviewComputingthingsGameplayUserinteractionGamegraphicsSoundandmusicSplashscreens,highscoresandotherpop-upsResourcesChangingresourcesFiles,registry,andexecutingprogramsDatastructuresCreatingparticlesMultiplayergamesUsingDLL's3DGraphics

GMLLanguageoverview

GameMakercontainsabuilt-inprogramminglanguage.Thisprogramminglanguagegivesyoumuchmoreflexibilityandcontrolthanthestandardactions.ThislanguagewewillrefertoasGML(theGameMakerLanguage).Thereareanumberofdifferentplaceswhereyoucantypeprogramsinthislanguage.Firstofall,whenyoudefinescripts.AscriptisaprograminGML.Secondly,whenyouaddacodeactiontoanevent.InacodeactionyouagainhavetoprovideaprograminGML.Thirdly,intheroomcreationcode.Andfinally,whereveryouneedtospecifyavalueinanaction,youcanalsouseanexpressioninGML.Anexpression,aswewillseebelowisnotacompleteprogram,butapieceofcoderesultinginavalue.

InthischapterwewilldescribethebasicstructureofprogramsinGML.WhenyouwanttouseprogramsinGML,thereareacoupleofthingsyouhavetobecarefulabout.Firstofall,forallyourresources(sprites,objects,sounds,etc.)youmustusenamesthatstartwithaletterandonlyconsistofletters,digitsandtheunderscore'_'symbol.Otherwiseyoucannotrefertothemfromwithintheprogram.Makesureallresourceshavedifferentnames.Alsobecarefulnottonameresourcesself,other,global,orallbecausethesehavespecialmeaninginthelanguage.Alsoyoushouldnotuseanyofthekeywords,indicatedbelow.

InformationontheGMLlanguagecanbefoundinthefollowingpages:

AProgramVariablesAssignmentsExpressionsExtraVariablesAddressingVariablesinOtherInstancesArraysIfStatementRepeatStatementWhileStatement

DoStatementForStatementSwitchStatementBreakStatementContinueStatementExitStatementFunctionsScriptsWithConstructionCommentFunctionsandVariablesinGML

Aprogram

Aprogramconsistsofasetofinstructions,calledstatements.Aprogrammuststartwiththesymbol'{'andendwiththesymbol'}'.Betweenthesesymbolstherearethestatements.Statementsmustbeseparatedwitha';'symbol.Sotheglobalstructureofeveryprogramis:

{

<statement>;

<statement>;

...

}

Thereareanumberofdifferenttypesofstatements,whichwillbediscussedbelow.

Variables

LikeanyprogramminglanguageGMLcontainsvariables.Variablesarememorylocationsthatstoreinformation.Theyhaveanamesothatyoucanrefertothem.AvariableinGMLcanstoreeitherarealnumberorastring.Variablesdonotneedtobedeclaredlikeinmanyotherlanguages.Therearealargenumberofbuilt-invariables.Somearegeneral,likemouse_xandmouse_ythatindicatethecurrentmouseposition,whileallothersarelocaltotheobjectinstanceforwhichweexecutetheprogram,likexandythatindicatethecurrentpositionoftheinstance.Avariablehasanamethatmuststartwithaletterandcancontainonlyletters,numbers,andtheunderscoresymbol'_'.(Themaximallengthis64symbols.)Whenyouuseanewvariableitislocaltothecurrentinstanceandisnotknowninprogramsforotherinstances(evenofthesameobject).Youcanthoughrefertovariablesinotherinstances;seebelow.

Assignments

Anassignmentstoresavalueinavariable.Anassignmenthastheform:

<variable>=<expression>;

Anexpressioncanbeasimplevaluebutcanalsobemorecomplicated.Ratherthanassigningavaluetoavariable,onecanalsoaddthevaluetothecurrentvalueofthevariableusing+=.Similar,youcansubtractitusing-=,multiplyitusing*=,divideitusing/=,orusebitwiseoperatorsusing|=,&\,or^=.

Expressions

Expressionscanberealnumbers(e.g.3.4),hexadecimalnumbers,startingwitha$sign(e.g.$00FFAA),stringsbetweensingleordoublequotes(e.g.'hello'or“hello”)ormorecomplicatedexpressions.(Notethatstringscanrunovermultiplelines!)Forexpressions,thefollowingbinaryoperatorsexist(inorderofpriority):

&&||^^:combineBooleanvalues(&&=and,||=or,^^=xor)<<===!=>>=:comparisons,resultintrue(1)orfalse(0)|&^:bitwiseoperators(|=bitwiseor,&=bitwiseand,^=bitwisexor)<<>>:bitwiseoperators(<<=shiftleft,>>=shiftright)+-:addition,subtraction*/divmod:multiplication,division,integerdivision,andmodulo

Notethatvalueofxdivyisthevalueofx/yroundedinthedirectionofzerotothenearestinteger.Themodoperatorreturnstheremainderobtainedbydividingitsoperands.Inotherwords,xmody=x-(xdivy)*y.Also,thefollowingunaryoperatorsexist:

!:not,turnstrueintofalseandfalseintotrue-:negatesthenextvalue~:negatesthenextvaluebitwise

Asvaluesyoucanusenumbers,variables,orfunctionsthatreturnavalue.Sub-expressionscanbeplacedbetweenbrackets.Alloperatorsworkforrealvalues.Comparisonsalsoworkforstringsand+concatenatesstrings.(Pleasenotethat,contrarytocertainlanguages,bothargumentstoaBooleanoperationarealwayscomputed,evenwhenthefirstargumentalreadydeterminestheoutcome.)

Example

Hereisanexamplewithsomeassignments.

{

x=23;

color=$FFAA00;

str='helloworld';

y+=5;

x*=y;

x=y<<2;

x=23*((2+4)/sin(y));

str='hello'+"world";

b=(x<5)&&!(x==2||x==4);

}

Extravariables

Youcreatenewvariablesbyassigningavaluetothem(noneedtodeclarethemfirst).Ifyousimplyuseavariablename,thevariablewillbestoredwiththecurrentobjectinstanceonly.Sodon'texpecttofinditwhendealingwithanotherobject(oranotherinstanceofthesameobject)later.Youcanalsosetandreadvariablesinotherobjectsbyputtingtheobjectnamewithadotbeforethevariablename.

Tocreateglobalvariables,thatarevisibletoallobjectinstances,precedethemwiththewordglobalandadot.Soforexampleyoucanwrite:

{

if(global.doit)

{

//dosomething

global.doit=false;

}

}

Alternativelyyoucandeclarethevariablesasbeingglobal.Thisdeclarationlooksasfollows.

globalvar<varname1>,<varname2>,<varname3>,...;

Oncethisdeclarationhasbeenexecuted,thevariableisalwaystreatedasglobalwithouttheneedtoputthewordglobalandadotinfrontofit.Itonlyneedstobedeclaredonceinapieceofcodethatisexecuted.Afterthatinallotherplacesthevariableisconsideredasbeingglobal.

Sometimesyouwantvariablesonlywithinthecurrentpieceofcodeorscript.Inthiswayyouavoidwastingmemoryandyouaresurethereisnonamingconflict.Itisalsofasterthanusingglobalvariables.Toachievethisyoumustdeclarethevariablesatthebeginningofthepieceofcodeusingthekeywordvar.Thisdeclarationlooksasfollows.

var<varname1>,<varname2>,<varname3>,...;

Forexample,youcanwrite:

{

varxx,yy;

xx=x+10;

yy=y+10;

instance_create(xx,yy,ball);

}

Addressingvariablesinotherinstances

Asdescribedearlier,youcansetvariablesinthecurrentinstanceusingstatementslike

x=3;

Butinanumberofcasesyouwanttoaddressvariablesinanotherinstance.Forexample,youmightwanttostopthemotionofallballs,oryoumightwanttomovethemaincharactertoaparticularposition,or,inthecaseofacollision,youmightwanttosetthespritefortheotherinstanceinvolved.Thiscanbeachievedbyprecedingthevariablenamewiththenameofanobjectandadot.Soforexample,youcanwrite

ball.speed=0;

Thiswillchangethespeedofallinstancesofobjectball.Thereareanumberofspecial"objects".

self:Thecurrentinstanceforwhichweareexecutingtheactionother:Theotherinstanceinvolvedinacollisioneventall:Allinstancesnoone:Noinstanceatall(soundsweirdprobablybutitdoescomeinhandyaswewillseelateron)global:Notaninstanceatall,butacontainerthatstoresglobalvariables

So,forexample,youcanusethefollowingkindofstatements:

other.sprite_index=sprite5;

all.speed=0;

global.message='Agoodresult';

global.x=ball.x;

Nowyoumightwonderwhatthelastassignmentdoeswhentherearemultipleballs.Well,thefirstoneistakenanditsxvalueisassignedtothe

globalvalue.

Butwhatifyouwanttosetthespeedofoneparticularball,ratherthanallballs?Thisisslightlymoredifficult.Eachinstancehasauniqueid.Whenyouputinstancesinaroominthedesigner,thisinstanceidisshownwhenyourestthemouseontheinstance.Thesearenumberslargerthanorequalto100000.Suchanumberyoucanalsouseastheleft-handsideofthedot.Butbecareful.Thedotwillgetinterpretedasthedecimaldotinthenumber.Toavoidthis,putbracketsaroundit.Soforexample,assumingtheidoftheballis100032,youcanwrite:

(100032).speed=0;

Whenyoucreateaninstanceintheprogram,thecallreturnstheid.Soavalidpieceofprogramis

{

nnn=instance_create(100,100,ball);

nnn.speed=8;

}

Thiscreatesaballandsetsitsspeed.Notethatweassignedtheinstanceidtoavariableandusedthisvariableasindicationinfrontofthedot.Thisiscompletelyvalid.Letustrytomakethismoreprecise.Adotisactuallyanoperator.Ittakesavalueasleftoperandandavariable(address)asrightoperand,andreturnstheaddressofthisparticularvariableintheindicatedobjectorinstance.Alltheobjectnames,andthespecialobjectsindicatedabovesimplyrepresentvaluesandthesecanbedealtwithlikeanyvalue.Forexample,thefollowingprogramisvalid:

{

obj[0]=ball;

obj[1]=flag;

obj[0].alarm[4]=12;

obj[1].id.x=12;

}

Thelaststatementshouldbereadasfollows.Wetaketheidofthefirstflag.Fortheinstancewiththatidwesetthexcoordinateto12.

Objectnames,thespecialobjects,andtheinstanceid'scanalsobeusedinanumberoffunctions.Theyareactuallytreatedasconstantsintheprograms.

Arrays

Youcanuse1-and2-dimensionalarraysinGML.Simplyputtheindexbetweensquarebracketsfora1-dimensionalarray,andthetwoindiceswithacommabetweenthemfor2-dimensionalarrays.Atthemomentyouuseanindexthearrayisgenerated.Eacharrayrunsfromindex0.Sobecarefulwithusinglargeindicesbecausememoryforalargearraywillbereserved.Neverusenegativeindices.Thesystemputsalimitof32000oneachindexand1000000onthetotalsize.Soforexampleyoucanwritethefollowing:

{

a[0]=1;

i=1;

while(i<10){a[i]=2*a[i-1];i+=1;}

b[4,6]=32;

}

Ifstatement

Anifstatementhastheform

if(<expression>)<statement>

or

if(<expression>)<statement>else<statement>

Thestatementcanalsobeablock.Theexpressionwillbeevaluated.Ifthe(rounded)valueis<=0(false)thestatementafterelseisexecuted,otherwise(true)theotherstatementisexecuted.Itisagoodhabittoalwaysputcurlybracketsaroundthestatementsintheifstatement.Sobestuse

if(<expression>)

{

<statement>

}

else

{

<statement>

}

ExampleThefollowingprogrammovestheobjecttowardthemiddleofthescreen.

{

if(x<200){x+=4}else{x-=4};

}

Repeatstatement

Arepeatstatementhastheform

repeat(<expression>)<statement>

Thestatementisrepeatedthenumberoftimesindicatedbytheroundedvalueoftheexpression.

ExampleThefollowingprogramcreatesfiveballsatrandompositions.

{

repeat(5)instance_create(random(400),random(400),ball);

}

Whilestatement

Awhilestatementhastheform

while(<expression>)<statement>

Aslongastheexpressionistrue,thestatement(whichcanalsobeablock)isexecuted.Becarefulwithyourwhileloops.Youcaneasilymakethemloopforever,inwhichcaseyourgamewillhangandnotreacttoanyuserinputanymore.

ExampleThefollowingprogramtriestoplacethecurrentobjectatafreeposition(thisisaboutthesameastheactiontomoveanobjecttoarandomposition).

{

while(!place_free(x,y))

{

x=random(room_width);

y=random(room_height);

}

}

Dostatement

Adostatementhastheform

do<statement>until(<expression>)

Thestatement(whichcanalsobeablock)isexecuteduntiltheexpressionistrue.Thestatementisexecutedatleastonce.Becarefulwithyourdoloops.Youcaneasilymakethemloopforever,inwhichcaseyourgamewillhangandnotreacttoanyuserinputanymore.

ExampleThefollowingprogramtriestoplacethecurrentobjectatafreeposition(thisisaboutthesameastheactiontomoveanobjecttoarandomposition).

{

do

{



}

until(place_free(x,y))

}

Forstatement

Aforstatementhastheform

for(<statement1>;<expression>;<statement2>)<statement3>

Thisworksasfollows.Firststatement1isexecuted.Thentheexpressionisevaluated.Ifitistrue,statement3isexecuted;thenstatement2andthentheexpressionisevaluatedagain.Thiscontinuesuntiltheexpressionisfalse.

Thismaysoundcomplicated.Youshouldinterpretthisasfollows.Thefirststatementinitializesthefor-loop.Theexpressiontestswhethertheloopshouldbeended.Statement2isthestepstatementthatgoestothenextloopevaluation.

Themostcommonuseistohaveacounterrunthroughsomerange.

ExampleThefollowingprograminitializesanarrayoflength10withthevalues1-10.

{

for(i=0;i<=9;i+=1)list[i]=i+1;

}

Switchstatement

Inanumberofsituationsyouwanttoletyouractiondependonaparticularvalue.Youcandothisusinganumberofifstatementsbutitiseasiertousetheswitchstatement.Aswitchstatementhasthefollowingform:

switch(<expression>)

{

case<expression1>:<statement1>;...;break;

case<expression2>:<statement2>;...;break;

...

default:<statement>;...

}

Thisworksasfollows.Firsttheexpressionisexecuted.Nextitiscomparedwiththeresultsofthedifferentexpressionsafterthecasestatements.Theexecutioncontinuesafterthefirstcasestatementwiththecorrectvalue,untilabreakstatementisencountered.Ifnocasestatementhastherightvalue,executioniscontinuedafterthedefaultstatement.(Itisnotrequiredtohaveadefaultstatement.)Notethatmultiplecasestatementscanbeplacedforthesamestatement.Also,thebreakisnotrequired.Ifthereisnobreakstatementtheexecutionsimplycontinueswiththecodeforthenextcasestatement.

ExampleThefollowingprogramtakesactionbasedonakeythatispressed.

switch(keyboard_key)

{

casevk_left:

casevk_numpad4:

x-=4;break;

casevk_right:

casevk_numpad6:

x+=4;break;

}

Breakstatement

Thebreakstatementhastheform

break

Ifusedwithinafor-loop,awhile-loop,arepeat-loop,aswitchstatement,orawithstatement,itendthislooporstatement.Ifusedoutsidesuchastatementitendstheprogram(notthegame).

Continuestatement

Thecontinuestatementhastheform

continue

Ifusedwithinafor-loop,awhile-loop,arepeat-loop,orawithstatement,itcontinueswiththenextvalueforthelooporwithstatement.

Exitstatement

Theexitstatementhastheform

exit

Itsimplyendstheexecutionofthisscriptorpieceofcode.(Itdoesnotendtheexecutionofthegame!Forthisyouneedthefunctiongame_end();seebelow.)

Functions

Afunctionhastheformofafunctionname,followedbyzeroormoreargumentsbetweenbrackets,separatedbycommas.

<function>(<arg1>,<arg2>,...)

Therearetwotypesoffunctions.Firstofall,thereisahugecollectionofbuilt-infunctions,tocontrolallaspectsofyourgame.Secondly,anyscriptyoudefineinyourgamecanbeusedasafunction.

Notethatforafunctionwithoutargumentsyoustillneedtousethebrackets.Somefunctionsreturnvaluesandcanbeusedinexpressions.Otherssimplyexecutecommands.

Notethatitisimpossibletouseafunctionasthelefthandsideofanassignment.Forexample,youcannotwriteinstance_nearest(x,y,obj).speed=0.Insteadyoumustwrite(instance_nearest(x,y,obj)).speed=0.

Scripts

Whenyoucreateascript,youwanttoaccesstheargumentspassedtoit(eitherwhenusingthescriptaction,orwhencallingthescriptasafunctionfromaprogram(orfromanother,oreventhesamescript).Theseargumentsarestoredinthevariablesargument0,argument1,...,argument15.Sotherecanbeatmost16arguments.(Notethatwhencallingthescriptfromanaction,onlythefirst5argumentscanbespecified.)Youcanalsouseargument[0]etc.

Scriptscanalsoreturnavalue,sothattheycanbeusedinexpressions.Forthisendyouusethereturnstatement:

return<expression>

Executionofthescriptendsatthereturnstatement!

ExampleHereisthedefinitionforalittlescriptthatcomputesthesquareoftheargument:

{

return(argument0*argument0);

}

Tocallascriptfromwithinapieceofcode,justactthesamewayaswhencallingfunctions.Thatis,writethescriptnamewiththeargumentvaluesinparentheses.

Withconstructions

Asindicatedbefore,itispossibletoreadandchangethevalueofvariablesinotherinstances.Butinanumberofcasesyouwanttodoalotmorewithotherinstances.Forexample,imaginethatyouwanttomoveallballs8pixelsdown.Youmightthinkthatthisisachievedbythefollowingpieceofcode

ball.y=ball.y+8;

Butthisisnotcorrect.Therightsideoftheassignmentgetsthevalueofthey-coordinateofthefirstballandadds8toit.Nextthisnewvalueissetasy-coordinateofallballs.Sotheresultisthatallballsgetthesamey-coordinate.Thestatement

ball.y+=8;

willhaveexactlythesameeffectbecauseitissimplyanabbreviationofthefirststatement.Sohowdoweachievethis?Forthispurposethereisthewithstatement.Itsglobalformis

with(<expression>)<statement>

<expression>indicatesoneormoreinstances.Forthisyoucanuseaninstanceid,thenameofanobject(toindicateallinstancesofthisobject)oroneofthespecialobjects(all,self,other,noone).<statement>isnowexecutedforeachoftheindicatedinstances,asifthatinstanceisthecurrent(self)instance.So,tomoveallballs8pixelsdown,youcantype.

with(ball)y+=8;

Ifyouwanttoexecutemultiplestatements,putcurlybracketsaroundthem.Soforexample,tomoveallballstoarandomposition,youcanuse

with(ball)

{



}

Notethat,withinthestatement(s),theindicatedinstancehasbecometheselfinstance.Withinthestatementstheoriginalselfinstancehasbecometheotherinstance.Soforexample,tomoveallballstothepositionofthecurrentinstance,youcantype

with(ball)

{

x=other.x;

y=other.y;

}

Useofthewithstatementisextremelypowerful.Letmegiveafewmoreexamples.Todestroyallballsyoutype

with(ball)instance_destroy();

Ifabombexplodesandyouwanttodestroyallinstancesclosebyyoucanuse

with(all)

{

if(distance_to_object(other)<50)instance_destroy();

}

Comment

Youcanaddcommenttoyourprograms.Everythingonalineafter//isnotread.Youcanalsomakeamulti-linecommentbyplacingthetextbetween/*and*/.(Colorcodingmightnotworkcorrectlyhere!PressF12tore-colorcodethetextifanerroroccurs.)

FunctionsandvariablesinGML

GMLcontainsalargenumberofbuilt-infunctionsandvariables.Withtheseyoucancontrolanypartofthegame.Forallactionstherearecorrespondingfunctionssoyouactuallydon'tneedtouseanyactionsifyoupreferusingcode.Buttherearemanymorefunctionsandvariablesthatcontrolaspectsofthegamethatcannotbeusedwithactionsonly.Soifyouwanttomakeadvancedgamesyouarestronglyadvisedtoreadthroughthefollowingchapterstogetanoverviewofallthatispossible.Pleasenotethatthesevariablesandfunctionscanalsobeusedwhenprovidingvaluesforactions.Soevenifyoudon'tplanonusingcodeorwritingscripts,youwillstillbenefitfromthisinformation.

Thefollowingconventionisusedbelow.Variablenamesmarkedwitha*areread-only,thatis,theirvaluecannotbechanged.Variablenameswith[0..n]afterthemarearrays.Therangeofpossibleindicesisgiven.

Computingthings

GameMakercontainsalargenumberoffunctionstocomputecertainthings.Hereisacompletelist.

InformationontheGMLlanguagecanbefoundinthefollowingpages:

ConstantsReal-valuedfunctionsStringhandlingfunctionsDealingwithdatesandtime

Constants

Thefollowingmathematicalconstantsexist:

trueEqualto1.falseEqualto0.piEqualto3.1415...

Real-valuedfunctions

Thefollowingfunctionsexistthatdealwithrealnumbers.

random(x)Returnsarandomrealnumberbetween0andx.Thenumberisalwayssmallerthanx.random_range(x1,x2)Returnsarandomrealnumberbetweenx1(inclusive)andx2(exclusive).irandom(x)Returnsarandomintegernumberbetween0andx(inclusivewhenxisaninteger).irandom_range(x1,x2)Returnsarandomrealnumberbetweenx1(inclusive)andx2(inclusive).Bothx1andx2mustbeintegervalues(otherwisetheyareroundeddown).random_set_seed(seed)Setstheseed(aninteger)thatisusedfortherandomnumbergeneration.Canbeusedtorepeatthesamerandomsequence.(Notethoughthatalsosomeactionsandthesystemitselfusesrandomnumbers.)random_get_seed()Returnsthecurrentseed.randomize()Setstheseedtoarandomnumber.choose(val1,val2,val3,...)Returnsoneoftheargumentschoosenrandomly.Thefunctioncanhaveupto16arguments.abs(x)Returnstheabsolutevalueofx.sign(x)Returnsthesignofx(-1,0or1).round(x)Returnsxroundedtothenearestinteger.floor(x)Returnsthefloorofx,thatis,xroundeddowntoaninteger.ceil(x)Returnstheceilingofx,thatis,xroundeduptoaninteger.frac(x)Returnsthefractionalpartofx,thatis,thepartbehindthedecimaldot.sqrt(x)Returnsthesquarerootofx.xmustbenon-negative.sqr(x)Returnsx*x.power(x,n)Returnsxtothepowern.exp(x)Returnsetothepowerx.ln(x)Returnsthenaturallogarithmofx.log2(x)Returnsthelogbase2ofx.log10(x)Returnsthelogbase10ofx.

logn(n,x)Returnsthelogbasenofx.sin(x)Returnsthesineofx(xinradians).cos(x)Returnsthecosineofx(xinradians).tan(x)Returnsthetangentofx(xinradians).arcsin(x)Returnstheinversesineofx.arccos(x)Returnstheinversecosineofx.arctan(x)Returnstheinversetangentofx.arctan2(y,x)Calculatesarctan(Y/X),andreturnsanangleinthecorrectquadrant.degtorad(x)Convertsdegreestoradians.radtodeg(x)Convertsradianstodegrees.min(val1,val2,val3,...)Returnstheminimumofthevalues.Thefunctioncanhaveupto16arguments.Theymusteitherbeallrealorallstrings.max(val1,val2,val3,...)Returnsthemaximumofthevalues.Thefunctioncanhaveupto16arguments.Theymusteitherbeallrealorallstrings.mean(val1,val2,val3,...)Returnstheaverageofthevalues.Thefunctioncanhaveupto16arguments.Theymustallberealvalues.median(val1,val2,val3,...)Returnsthemedianofthevalues,thatis,themiddlevalue.(Whenthenumberofargumentsiseven,thesmallerofthetwomiddlevaluesisreturned.)Thefunctioncanhaveupto16arguments.Theymustallberealvalues.point_distance(x1,y1,x2,y2)Returnsthedistancebetweenpoint(x1,y1)andpoint(x2,y2).point_direction(x1,y1,x2,y2)Returnsthedirectionfrompoint(x1,y1)towardpoint(x2,y2)indegrees.lengthdir_x(len,dir)Returnsthehorizontalx-componentofthevectordeterminedbytheindicatedlengthanddirection.lengthdir_y(len,dir)Returnstheverticaly-componentofthevectordeterminedbytheindicatedlengthanddirection.is_real(x)Returnswhetherxisarealvalue(asopposedtoastring).is_string(x)Returnswhetherxisastring(asopposedtoarealvalue).

Stringhandlingfunctions

Thefollowingfunctionsdealwithcharactersandstring.

chr(val)Returnsastringcontainingthecharacterwithascicodeval.ord(str)Returnstheascicodeofthefirstcharacterinstr.real(str)Turnsstrintoarealnumber.strcancontainaminussign,adecimaldotandevenanexponentialpart.string(val)Turnstherealvalueintoastringusingastandardformat(nodecimalplaceswhenitisaninteger,andtwodecimalplacesotherwise).string_format(val,tot,dec)Turnsvalintoastringusingyourownformat:totindicatesthetotalnumberofplacesanddecindicatesthenumberofdecimalplaces.string_length(str)Returnsthenumberofcharactersinthestring.string_pos(substr,str)Returnsthepositionofsubstrinstr(0=nooccurrence).string_copy(str,index,count)Returnsasubstringofstr,startingatpositionindex,andoflengthcount.string_char_at(str,index)Returnsthecharacterinstratpositionindex.string_delete(str,index,count)Returnsacopyofstrwiththepartremovedthatstartsatpositionindexandhaslengthcount.string_insert(substr,str,index)Returnsacopyofstrwithsubstraddedatpositionindex.string_replace(str,substr,newstr)Returnsacopyofstrwiththefirstoccurrenceofsubstrreplacedbynewstr.string_replace_all(str,substr,newstr)Returnsacopyofstrwithalloccurrencesofsubstrreplacedbynewstr.string_count(substr,str)Returnsthenumberofoccurrencesofsubstrinstr.string_lower(str)Returnsalowercasecopyofstr.string_upper(str)Returnsanuppercasecopyofstr.string_repeat(str,count)Returnsastringconsistingofcountcopiesofstr.

string_letters(str)Returnsastringthatonlycontainsthelettersinstr.string_digits(str)Returnsastringthatonlycontainsthedigitsinstr.string_lettersdigits(str)Returnsastringthatcontainsthelettersanddigitsinstr.

Thefollowingfunctionsdealwiththeclipboardforstoringtext.

clipboard_has_text()Returnswhetherthereisanytextontheclipboard.clipboard_get_text()Returnsthecurrenttextontheclipboard.clipboard_set_text(str)Setsthestringstrontheclipboard.

Dealingwithdatesandtime

InGameMakerthereareanumberoffunctionstodealwithdatesandtime.Adate-timecombinationisstoredinarealnumber.Theintegralpartofadate-timevalueisthenumberofdaysthathavepassedsince12/30/1899.Thefractionalpartofthedate-timevalueisfractionofa24hourdaythathaselapsed.Thefollowingfunctionsexist:

date_current_datetime()Returnsthedate-timevaluethatcorrespondstothecurrentmoment.date_current_date()Returnsthedate-timevaluethatcorrespondstothecurrentdateonly(ignoringthetime).date_current_time()Returnsthedate-timevaluethatcorrespondstothecurrenttimeonly(ignoringthedate).date_create_datetime(year,month,day,hour,minute,second)Createsadate-timevaluecorrespondingtotheindicateddateandtime.date_create_date(year,month,day)Createsadate-timevaluecorrespondingtotheindicateddate.date_create_time(hour,minute,second)Createsadate-timevaluecorrespondingtotheindicatedtime.date_valid_datetime(year,month,day,hour,minute,second)Returnswhethertheindicateddateandtimearevalid.date_valid_date(year,month,day)Returnswhethertheindicateddateisvalid.date_valid_time(hour,minute,second)Returnswhethertheindicatedtimeisvalid.date_inc_year(date,amount)Returnsanewdatethatisamountyearsaftertheindicateddate.amountmustbeanintegernumber.date_inc_month(date,amount)Returnsanewdatethatisamountmonthsaftertheindicateddate.amountmustbeanintegernumber.date_inc_week(date,amount)Returnsanewdatethatisamountweeksaftertheindicateddate.amountmustbeanintegernumber.date_inc_day(date,amount)Returnsanewdatethatisamountdaysaftertheindicateddate.amountmustbeanintegernumber.date_inc_hour(date,amount)Returnsanewdatethatisamount

hoursaftertheindicateddate.amountmustbeanintegernumber.date_inc_minute(date,amount)Returnsanewdatethatisamountminutesaftertheindicateddate.amountmustbeanintegernumber.date_inc_second(date,amount)Returnsanewdatethatisamountsecondsaftertheindicateddate.amountmustbeanintegernumber.date_get_year(date)Returnstheyearcorrespondingtothedate.date_get_month(date)Returnsthemonthcorrespondingtothedate.date_get_week(date)Returnstheweekoftheyearcorrespondingtothedate.date_get_day(date)Returnsthedayofthemonthcorrespondingtothedate.date_get_hour(date)Returnsthehourcorrespondingtothedate.date_get_minute(date)Returnstheminutecorrespondingtothedate.date_get_second(date)Returnsthesecondcorrespondingtothedate.date_get_weekday(date)Returnsthedayoftheweekcorrespondingtothedate.date_get_day_of_year(date)Returnsthedayoftheyearcorrespondingtothedate.date_get_hour_of_year(date)Returnsthehouroftheyearcorrespondingtothedate.date_get_minute_of_year(date)Returnstheminuteoftheyearcorrespondingtothedate.date_get_second_of_year(date)Returnsthesecondoftheyearcorrespondingtothedate.date_year_span(date1,date2)Returnsthenumberofyearsbetweenthetwodates.Itreportsincompleteyearsasafraction.date_month_span(date1,date2)Returnsthenumberofmonthsbetweenthetwodates.Itreportsincompletemonthsasafraction.date_week_span(date1,date2)Returnsthenumberofweeksbetweenthetwodates.Itreportsincompleteweeksasafraction.date_day_span(date1,date2)Returnsthenumberofdaysbetweenthetwodates.Itreportsincompletedaysasafraction.date_hour_span(date1,date2)Returnsthenumberofhoursbetweenthetwodates.Itreportsincompletehoursasafraction.date_minute_span(date1,date2)Returnsthenumberofminutes

betweenthetwodates.Itreportsincompleteminutesasafraction.date_second_span(date1,date2)Returnsthenumberofsecondsbetweenthetwodates.Itreportsincompletesecondsasafraction.date_compare_datetime(date1,date2)Comparesthetwodate-timevalues.Returns-1,0,or1dependingonwhetherthefirstissmaller,equal,orlargerthanthesecondvalue.date_compare_date(date1,date2)Comparesthetwodate-timevaluesonlytakingthedatepartintoaccount.Returns-1,0,or1dependingonwhetherthefirstissmaller,equal,orlargerthanthesecondvalue.date_compare_time(date1,date2)Comparesthetwodate-timevaluesonlytakingthetimepartintoaccount.Returns-1,0,or1dependingonwhetherthefirstissmaller,equal,orlargerthanthesecondvalue.date_date_of(date)Returnsthedatepartoftheindicateddate-timevalue,settingthetimepartto0.date_time_of(date)Returnsthetimepartoftheindicateddate-timevalue,settingthedatepartto0.date_datetime_string(date)Returnsastringindicatingthegivendateandtimeinthedefaultformatforthesystem.date_date_string(date)Returnsastringindicatingthegivendateinthedefaultformatforthesystem.date_time_string(date)Returnsastringindicatingthegiventimeinthedefaultformatforthesystem.date_days_in_month(date)Returnsthenumberofdaysinthemonthindicatedbythedate-timevalue.date_days_in_year(date)Returnsthenumberofdaysintheyearindicatedbythedate-timevalue.date_leap_year(date)Returnswhethertheyearindicatedbythedate-timevalueisaleapyear.date_is_today(date)Returnswhethertheindicateddate-timevalueisontoday.

Gameplay

Therearealargenumberofvariablesandfunctionsthatyoucanusetodefinethegameplay.Theseinparticularinfluencethemovementandcreationofinstances,thetiming,theroom,andthehandlingofevents.

Informationongameplaycanbefoundinthefollowingpages:

MovingAroundPathsMotionPlanningCollisionDetectionInstancesDeactivatingInstancesTimingRoomsScoreGeneratingEventsMiscellaneousVariablesandFunctions

Movingaround

Obviously,animportantaspectofgamesisthemovingaroundofobjectinstances.Eachinstancehastwobuilt-invariablesxandythatindicatethepositionoftheinstance.(Tobeprecise,theyindicatetheplacewheretheoriginofthespriteisplaced.Position(0,0)isthetop-leftcorneroftheroom.Youcanchangethepositionoftheinstancebychangingitsxandyvariables.Ifyouwanttheobjecttomakecomplicatedmotionsthisisthewaytogo.Youtypicallyputthiscodeinthestepeventfortheobject.

Iftheobjectmoveswithconstantspeedanddirection,thereisaneasierwaytodothis.Eachobjectinstancehasahorizontalspeed(hspeed)andaverticalspeed(vspeed).Bothareindicatedinpixelsperstep.Apositivehorizontalspeedmeansamotiontotheright,anegativehorizontalspeedmeanamotiontotheleft.Positiveverticalspeedisdownwardsandnegativeverticalspeedisupwards.Soyouhavetosetthesevariablesonlyonce(forexampleinthecreatingevent)togivetheobjectinstanceaconstantmotion.

Thereisquiteadifferentwayforspecifyingmotion,usingadirection(indegrees0-359),andaspeed(shouldbenon-negative).Youcansetandreadthesevariablestospecifyanarbitrarymotion.(Internallythisischangedintovaluesforhspeedandvspeed.)Alsothereisthefrictionandthegravityandgravitydirection.Finally,thereisthefunctionmotion_add(dir,speed)toaddamotiontothecurrentone.

Tobecomplete,eachinstancehasthefollowingvariablesandfunctionsdealingwithitspositionandmotion:

xItsx-position.yItsy-position.xpreviousItspreviousx-position.ypreviousItspreviousy-position.xstartItsstartingx-positionintheroom.ystartItsstartingy-positionintheroom.hspeedHorizontalcomponentofthespeed.

vspeedVerticalcomponentofthespeed.directionItscurrentdirection(0-360,counter-clockwise,0=totheright).speedItscurrentspeed(pixelsperstep).frictionCurrentfriction(pixelsperstep).gravityCurrentamountofgravity(pixelsperstep).gravity_directionDirectionofgravity(270isdownwards).motion_set(dir,speed)Setsthemotionwiththegivenspeedindirectiondir.motion_add(dir,speed)Addsthemotiontothecurrentmotion(asavectoraddition).

Therearealargenumberoffunctionsavailablethathelpyouindefiningyourmotions:

place_free(x,y)Returnswhethertheinstanceplacedatposition(x,y)iscollision-free.Thisistypicallyusedasacheckbeforeactuallymovingtothenewposition.place_empty(x,y)Returnswhethertheinstanceplacedatposition(x,y)meetsnobody.Sothisfunctiontakesalsonon-solidinstancesintoaccount.place_meeting(x,y,obj)Returnswhethertheinstanceplacedatposition(x,y)meetsobj.objcanbeanobjectinwhichcasethefunctionreturnstrueissomeinstanceofthatobjectismet.Itcanalsobeaninstanceid,thespecialwordallmeaninganinstanceofanyobject,orthespecialwordother.place_snapped(hsnap,vsnap)Returnswhethertheinstanceisalignedwiththesnappingvalues.move_random(hsnap,vsnap)Movestheinstancetoafreerandom,snappedposition,likethecorrespondingaction.move_snap(hsnap,vsnap)Snapstheinstance,likethecorrespondingaction.move_wrap(hor,vert,margin)Wrapstheinstancewhenithaslefttheroomtotheotherside.horindicateswhethertowraphorizontalyandvertindicateswhethertowrapvertically.marginindicateshowfartheoriginoftheinstancemustbeoutsidetheroombeforethewraphappens.Soitisamarginaroundtheroom.Youtypicallyusethis

functionintheOutsideevent.move_towards_point(x,y,sp)Movestheinstanceswithspeedsptowardposition(x,y).move_bounce_solid(adv)Bouncesagainstsolidinstances,likethecorrespondingaction.advindicateswhethertouseadvancebounce,thatalsotakesslantedwallsintoaccount.move_bounce_all(adv)Bouncesagainstallinstances,insteadofjustthesolidones.move_contact_solid(dir,maxdist)Movestheinstanceinthedirectionuntilacontactpositionwithasolidobjectisreached.Ifthereisnocollisionatthecurrentposition,theinstanceisplacedjustbeforeacollisionoccurs.Iftherealreadyisacollisiontheinstanceisnotmoved.Youcanspecifythemaximaldistancetomove(useanegativenumberforanarbitrarydistance).move_contact_all(dir,maxdist)Sameasthepreviousfunctionbutthistimeyoustopatacontactwithanyobject,notjustsolidobjects.move_outside_solid(dir,maxdist)Movestheinstanceinthedirectionuntilitnolongerlieswithinasolidobject.Ifthereisnocollisionatthecurrentpositiontheinstanceisnotmoved.Youcanspecifythemaximaldistancetomove(useanegativenumberforanarbitrarydistance).move_outside_all(dir,maxdist)Sameasthepreviousfunctionbutthistimeyoumoveuntiloutsideanyobject,notjustsolidobjects.distance_to_point(x,y)Returnsthedistanceoftheboundingboxofthecurrentinstanceto(x,y).(Iftheinstancedoesnothaveaspriteormask,theresultofthefunctionisundefined.)distance_to_object(obj)Returnsthedistanceoftheinstancetothenearestinstanceofobjectobj.(Iftheinstanceorobjectdoesnothaveaspriteormask,theresultofthefunctionisundefined.)position_empty(x,y)Returnswhetherthereisnothingatposition(x,y).position_meeting(x,y,obj)Returnswhetheratposition(x,y)thereisaninstanceobj.objcanbeanobject,aninstanceid,orthekeywordsself,other,orall.

Paths

InGameMakeryoucandefinepathsandorderinstancestofollowsuchpaths.Althoughyoucanuseactionsforthis,therearefunctionsandvariablesthatgiveyoumoreflexibility:

path_start(path,speed,endaction,absolute)Startsapathforthecurrentinstance.Thepathisthenameofthepathyouwanttostart.Thespeedisthespeedwithwhichthepathmustbefollowed.Anegativespeedmeansthattheinstancemovesbackwardsalongthepath.Theendactionindicateswhatshouldhappenwhentheendofthepathisreached.Thefollowingvaluescanbeused:

0:stopthepath1:continuefromthestartposition(ifthepathisnotclosedwejumptothestartposition2:continuefromthecurrentposition3:reversethepath,thatischangethesignofthespeed

Theargumentabsoluteshouldbetrueorfalse.Whentruetheabsolutecoordinatesofthepathareused.Whenfalsethepathisrelativetothecurrentpositionoftheinstance.Tobemoreprecise,ifthespeedispositive,thestartpointofthepathwillbeplacedonthecurrentpositionandthepathisfollowedfromthere.Whenthespeedisnegativetheendpointofthepathwillbeplacedonthecurrentpositionandthepathisfollowedbackwardsfromthere.path_end()Endsthefollowingofapathforthecurrentinstance.path_index*Indexofthecurrentpaththeinstancefollows.Youcannotchangethisdirectlybutmustusethefunctionabove.path_positionPositioninthecurrentpath.0isthebeginningofthepath.1istheendofthepath.Thevaluemustliebetween0and1.path_positionpreviousPreviouspositioninthecurrentpath.Thiscanbeusede.g.incollisioneventstosetthepositiononthepathbacktothepreviousposition.path_speedSpeed(inpixelsperstep)withwhichthepathmustbefollowed.Useanegativespeedtomovebackwards.

path_orientationOrientation(counter-clockwise)intowhichthepathisperformed.0isthenormalorientationofthepath.path_scaleScaleofthepath.Increasetomakethepathlarger.1isthedefaultvalue.path_endactionTheactionthatmustbeperformedattheendofthepath.Youcanusethevaluesindicatedabove.

Motionplanning

Motionplanninghelpsyoutomovecertaininstancesfromagivenlocationtoadifferentlocationwhileavoidingcollisionswithcertainotherinstances(e.g.walls).Motionplanningisadifficultproblem.Itisimpossibletogivegeneralfunctionsthatwillworkproperlyinallsituations.Also,computingcollisionfreemotionsisatime-consumingoperation.Soyouhavebecarefulhowandwhenyouapplyit.Pleasekeeptheseremarksinmindwhenyouuseanyofthefollowingfunctions.

DifferentformsofmotionplanningareprovidedbyGameMaker.Thesimplestformletsaninstancetakeasteptowardsaparticulargoalposition,tryingtogostraightifpossiblebuttakingadifferentdirectionifrequired.Thesefunctionsshouldbeusedinthestepeventofaninstance.Theycorrespondtothemotionplanningactionsthatarealsoavailable:

mp_linear_step(x,y,stepsize,checkall)Thisfunctionletstheinstancetakeastepstraighttowardstheindicatedposition(x,y).Thesizeofthestepisindicatedbythestepsize.Iftheinstanceisalreadyatthepositionitwillnotmoveanyfurther.Ifcheckallistruetheinstancewillstopwhenithitsaninstanceofanyobject.Ifitisfalseitonlystopswhenhittingasolidinstance.Notethatthisfunctiondoesnottrytomakedetoursifitmeetsanobstacle.Itsimplyfailsinthatcase.Thefunctionreturnswhetherornotthegoalpositionwasreached.mp_linear_step_object(x,y,stepsize,obj)Sameasthefunctionabovebutthistimeonlyinstancesofobjareconsideredasobstacles.objcanbeanobjectoraninstanceid.mp_potential_step(x,y,stepsize,checkall)Likethepreviousfunction,thisfunctionletstheinstancetakeasteptowardsaparticularposition.Butinthiscaseittriestoavoidobstacles.Whentheinstancewouldrunintoasolidinstance(oranyinstancewhencheckallistrue)itwillchangethedirectionofmotiontotrytoavoidtheinstanceandmovearoundit.Theapproachisnotguaranteedto

workbutinmosteasycasesitwilleffectivelymovetheinstancetowardsthegoal.Thefunctionreturnswhetherornotthegoalwasreached.mp_potential_step_object(x,y,stepsize,obj)Sameasthefunctionabovebutthistimeonlyinstancesofobjareconsideredasobstacles.objcanbeanobjectoraninstanceid.mp_potential_settings(maxrot,rotstep,ahead,onspot)Thepreviousfunctiondoesitsworkusinganumberofparametersthatcanbechangedusingthisfunction.Globallythemethodworksasfollows.Itfirsttriestomovestraighttowardsthegoal.Itlooksanumberofstepsaheadwhichcanbesetwiththeparameterahead(default3).Reducingthisvaluemeansthattheinstancewillstartchangingdirectionlater.Increasingitmeansitwillstartchangingdirectionearlier.Ifthischeckleadstoacollisionitstartslookingatdirectionsmoretotheleftandtotherightofthebestdirection.Itdoesthisinstepsofsizerotstep(default10).Reducingthisgivestheinstancemoremovementpossibilitiesbutwillbeslower.Theparametermaxrotisabitmoredifficulttoexplain.Theinstancehasacurrentdirection.maxrot(default30)indicateshowmuchitisallowedtochangeitscurrentdirectioninastep.Soevenifitcanmovee.g.straighttothegoalitwillonlydosoifitdoesnotviolatethismaximalchangeofdirection.Ifyoumakemaxrotlargetheinstancecanchangealotineachstep.Thiswillmakeiteasiertofindashortpathbutthepathwillbeuglier.Ifyoumakethevaluesmallerthepathwillbesmootherbutitmighttakelongerdetours(andsometimesevenfailtofindthegoal).Whennostepcanbemadethebehaviordependsonthevalueoftheparameteronspot.Ifonspotistrue(thedefaultvalue),theinstancewillrotateonitsspotbytheamountindicatedwithmaxrot.Ifitisfalseitwillnotmoveatall.Settingittofalseisusefulfore.g.carsbutreducesthechanceoffindingapath.

Pleasenotethatthepotentialapproachusesonlylocalinformation.Soitwillonlyfindapathifthislocalinformationisenoughtodeterminetherightdirectionofmotion.Forexample,itwillfailtofindapathoutofamaze(mostofthetime).

Thesecondkindoffunctionscomputesacollision-freepathforthe

instance.Oncethispathhasbeencomputedyoucanassignittotheinstancetomovetowardsthegoal.Thecomputationofthepathwilltakesometimebutafterthattheexecutionofthepathwillbefast.Ofcoursethisisonlyvalidifthesituationhasnotchangedinthemeantime.Forexample,ifobstacleschangeyoupossiblywillneedtorecomputethepath.Againnoticethatthesefunctionsmightfail.ThesefunctionsareonlyavailableintheProEditionofGameMaker.

Thefirsttwofunctionsusethelinearmotionandpotentialfieldapproachthatwerealsousedforthestepfunctions.

mp_linear_path(path,xg,yg,stepsize,checkall)Thisfunctioncomputesastraight-linepathfortheinstancefromitscurrentpositiontotheposition(xg,yg)usingtheindicatedstepsize.Itusesstepsasinthefunctionmp_linear_step().Theindicatedpathmustalreadyexistandwillbeoverwrittenbythenewpath.(Seealaterchapteronhowtocreateanddestroypaths.)Thefunctionwillreturnwhetherapathwasfound.Thefunctionwillstopandreportfailureifnostraightpathexistsbetweenstartandgoal.Ifitfailsapathisstillcreatedthatrunstillthepositionwheretheinstancewasblocked.mp_linear_path_object(path,xg,yg,stepsize,obj)Sameasthefunctionabovebutthistimeonlyinstancesofobjareconsideredasobstacles.objcanbeanobjectoraninstanceid.mp_potential_path(path,xg,yg,stepsize,factor,checkall)Thisfunctioncomputesapathfortheinstancefromitscurrentpositionandorientationtotheposition(xg,yg)usingtheindicatedstepsizetryingtoavoidcollisionwithobstacles.Itusespotentialfieldsteps,likeinthefunctionmp_potential_step()andalsotheparametersthatcanbesetwithmp_potential_settings().Theindicatedpathmustalreadyexistandwillbeoverwrittenbythenewpath.(Seealaterchapteronhowtocreateanddestroypaths.)Thefunctionwillreturnwhetherapathwasfound.Toavoidthefunctioncontinuingtocomputeforeveryouneedtoprovidealengthfactorlargerthan1.Thefunctionwillstopandreportfailureifitcannotfindapathshorterthanthisfactortimesthedistancebetweenstartandgoal.Afactorof4isnormallygoodenoughbutifyouexpectlongdetoursyoumightmakeitlonger.Ifitfailsapathisstillcreatedthatrunsinthedirection

ofthegoalbutitwillnotreachit.mp_potential_path_object(path,xg,yg,stepsize,factor,obj)Sameasthefunctionabovebutthistimeonlyinstancesofobjareconsideredasobstacles.objcanbeanobjectoraninstanceid.

Theotherfunctionsuseamuchmorecomplexmechanismusingagrid-basedapproach(sometimescalledanA*algorithm).Itwillbemoresuccessfulinfindingpaths(althoughitstillmightfail)andwillfindshorterpathsbutitrequiredmoreworkonyourside.Theglobalideaisasfollows.Firstofallweputagridon(therelevantpartof)theroom.Youcanchoosetouseafinegrid(whichwillbeslower)oracoarsegrid.Next,forallrelevantobjectswedeterminethegridcellstheyoverlap(eitherusingboundingboxesorprecisechecking)andmarkthesecellsasbeingforbidden.Soacellwillbemarkedtotallyforbidden,evenifitonlypartiallyoverlapswithanobstacle.Finallywespecifyastartandagoalposition(whichmustlieinfreecells)andthefunctioncomputestheshortestpath(actuallyclosetotheshortest)betweenthese.Thepathwillrunbetweencentersoffreecells.Soifthecellsarelargeenoughsothattheinstanceplacedatitscenterwillliecompletelyinsideitthiswillbesuccessful.Thispathyoucannowgivetoaninstancetofollow.

Thegrid-basedapproachisverypowerful(andisusedinmanyprofessionalgames)butitrequiresthatyoudosomecarefulthinking.Youmustdeterminewhichareaandcellsizearegoodenoughforsolvingthegame.Alsoyoumustdeterminewhichobjectsmustbeavoidedandwhetherprecisecheckingisimportant.Alltheseparametersstronglyinfluencetheefficiencyoftheapproach.

Inparticularthesizeofthecellsiscrucial.Rememberthatthecellsmustbelargeenoughsothatthemovingobjectplacedwithitsoriginonthecenterofacellmustliecompletelyinsidethecell.(Becarefulaboutthepositionoftheoriginoftheobject.Alsorealizethatyoucanshiftthepathiftheoriginoftheobjectisnotinitscenter!)Ontheotherhand,thesmallerthecellsthemorepossiblepathsexist.Ifyoumakecellstoolarge,openingsbetweenobstaclesmaygetclosedbecauseallcellsintersectanobstacle.

Theactualfunctionsforthegrid-basedapproachareasfollows:

mp_grid_create(left,top,hcells,vcells,cellwidth,cellheight)Thisfunctioncreatesthegrid.Itreturnsanindexthatmustbeusedinallothercalls.Youcancreateandmaintainmultiplegridstructuresatthesamemoment.leftandtopindicatethepositionofthetop-leftcornerofthegrid.hcellsandvcellsindicatethenumberofhorizontalandverticalcells.Finallycellwidthandcellheightindicatethesizeofthecells.mp_grid_destroy(id)Destroystheindicatedgridstructureandfreesitsmemory.Don'tforgettocallthisifyoudon'tneedthestructureanymore.mp_grid_clear_all(id)Markallcellsinthegridtobefree.mp_grid_clear_cell(id,h,v)Clearstheindicatedcell.Cell0,0isthetopleftcell.mp_grid_clear_rectangle(id,left,top,right,bottom)Clearsallcellsthatintersecttheindicatedrectangle(inroomcoordinates).mp_grid_add_cell(id,h,v)Markstheindicatedcellasbeingforbidden.Cell0,0isthetopleftcell.mp_grid_add_rectangle(id,left,top,right,bottom)Marksallcellsthatintersecttheindicatedrectangleasbeingforbidden.mp_grid_add_instances(id,obj,prec)Marksallcellsthatintersectaninstanceoftheindicatedobjectasbeingforbidden.Youcanalsouseanindividualinstancebymakingobjtheidoftheinstance.Alsoyoucanusethekeywordalltoindicateallinstancesofallobjects.precindicateswhetherprecisecollisioncheckingmustbeused(willonlyworkifprecisecheckingisenabledforthespriteusedbytheinstance).mp_grid_path(id,path,xstart,ystart,xgoal,ygoal,allowdiag)

Computesapaththroughthegrid.pathmustindicateanexistingpaththatwillbereplacedbythecomputerpath.xstartandystartindicatethestartofthepathandxgoalandygoalthegoal.allowdiagindicateswhetherdiagonalmovesareallowedinsteadofjusthorizontalorvertical.Thefunctionreturnswhetheritsucceededinfindingapath.(Notethatthepathisindependentofthecurrentinstance;Itisapaththroughthegrid,notapathforaspecificinstance.)mp_grid_draw(id)Thisfunctiondrawsthegridwithgreencellsbeingfreeandredcellsbeingforbidden.Thisfunctionisslowandonly

providedasadebugtool.

Collisionchecking

Whenplanningmotionsordecidingoncertainactions,itisoftenimportanttoseewhethertherearecollisionswithotherobjectsatcertainplaces.Thefollowingroutinescanbeusedforthis.Allthesehavethreeargumentsincommon:Theargumentobjcanbeanobject,thekeywordall,ortheidofaninstance.Theargumentprecindicateswhetherthecheckshouldbepreciseoronlybasedontheboundingboxoftheinstance.Precisecheckingisonlydonewhenthespritefortheinstancehastheprecisecollisioncheckingset.Theargumentnotmecanbesettotruetoindicatethatthecallinginstanceshouldnotbechecked.Allthesefunctionsreturneithertheidofoneoftheinstancesthatcollide,ortheyreturnanegativevaluewhenthereisnocollision.

collision_point(x,y,obj,prec,notme)Thisfunctiontestswhetheratpoint(x,y)thereisacollisionwithentitiesofobjectobj.collision_rectangle(x1,y1,x2,y2,obj,prec,notme)Thisfunctiontestswhetherthereisacollisionbetweenthe(filled)rectanglewiththeindicatedoppositecornersandentitiesofobjectobj.Forexample,youcanusethistotestwhetheranareaisfreeofobstacles.collision_circle(xc,yc,radius,obj,prec,notme)Thisfunctiontestswhetherthereisacollisionbetweenthe(filled)circlecenteredatposition(xc,yc)withthegivenradiusandentitiesofobjectobj.Forexample,youcanusethistotestwhetherthereisanobjectclosetoaparticularlocation.collision_ellipse(x1,y1,x2,y2,obj,prec,notme)Thisfunctiontestswhetherthereisacollisionbetweenthe(filled)ellipsewiththeindicatedoppositecornersandentitiesofobjectobj.collision_line(x1,y1,x2,y2,obj,prec,notme)Thisfunctiontestswhetherthereisacollisionbetweenthelinesegmentfrom(x1,y1)to(x2,y2)andentitiesofobjectobj.Thisisapowerfulfunction.Youcane.g.useittotestwhetheraninstancecanseeanotherinstancebycheckingwhetherthelinesegmentbetweenthemintersectsawall.

Instances

Inthegame,thebasicunitsaretheinstancesofthedifferentobjects.Duringgameplayyoucanchangeanumberofaspectsoftheseinstances.Alsoyoucancreatenewinstancesanddestroyinstances.Besidesthemovementrelatedvariablesdiscussedaboveandthedrawingrelatedvariablesdiscussedbelow,eachinstancehasthefollowingvariables:

object_index*Indexoftheobjectthisisaninstanceof.Thisvariablecannotbechanged.id*Theuniqueidentifierfortheinstance(>=100000).(Notethatwhendefiningroomstheidoftheinstanceunderthemouseisalwaysindicated.)mask_indexIndexofthespriteusedasmaskforcollisions.Givethisavalueof-1tomakeitthesameasthesprite_index.solidWhethertheinstanceissolid.Thiscanbechangedduringthegame.persistentWhethertheinstanceispersistentandwillreappearwhenmovingtoanotherroom.Youoftenwanttoswitchpersistenceoffatcertainmoments.(Forexampleifyougobacktothefirstroom.)

Thereisoneproblemwhendealingwithinstances.Itisnotsoeasytoidentifyindividualinstances.Theydon'thaveaname.Whenthereisonlyoneinstanceofaparticularobjectyoucanusetheobjectnamebutotherwiseyouneedtogettheidoftheinstance.Thisisauniqueidentifierfortheinstance.youcanuseitinwithstatementsandasobjectidentifier.Fortunatelythereareanumberofvariablesandroutinesthathelpyoulocateinstanceid's.

instance_count*Numberofinstancesthatcurrentlyexistintheroom.instance_id[0..n-1]*Theidoftheparticularinstance.Herenisthenumberofinstance.

Notethattheassignmentoftheinstancestotheinstanceid'schangeseverystepsoyoucannotusevaluesfromprevioussteps.Alsopleasenotethatinstancesthataredeletedwillremaininthelistuntiltheendofthestep.Soifyouarealsodeletinginstancesyouneedtocheckwhethertheinstancestillexists.Letmegiveanexample.Assumeeachunitinyourgamehasaparticularpowerandyouwanttolocatethestrongestone,youcouldusethefollowingcode:

{

maxid=-1;

maxpower=0;

for(i=0;i<instance_count;i+=1)

{

iii=instance_id[i];

if(instance_exists(iii))

if(iii.object_index==unit)

{

if(iii.power>maxpower)

{maxid=iii;maxpower=iii.power;}

}

}

}

Aftertheloopmaxidwillcontaintheidoftheunitwithlargestpower.Ofcourse,forthisparticularsituationthefollowingcodewouldbebetter:

{

maxid=-1;

maxpower=0;

with(unit)do

{

if(power>maxpower)

{maxid=self;maxpower=power;}

}

}

instance_find(obj,n)Returnstheidofthe(n+1)'thinstanceoftypeobj.objcanbeanobjectorthekeywordall.Ifitdoesnotexist,thespecialobjectnooneisreturned.Notethattheassignmentoftheinstancestotheinstanceid'schangeseverystepsoyoucannotusevaluesfromprevioussteps.

instance_exists(obj)Returnswhetheraninstanceoftypeobjexists.objcanbeanobject,aninstanceid,orthekeywordall.instance_number(obj)Returnsthenumberofinstancesoftypeobj.objcanbeanobjectorthekeywordall.instance_position(x,y,obj)Returnstheidoftheinstanceoftypeobjatposition(x,y).Whenmultipleinstancesareatthatpositionthefirstisreturned.objcanbeanobjectorthekeywordall.Ifitdoesnotexist,thespecialobjectnooneisreturned.instance_nearest(x,y,obj)Returnstheidoftheinstanceoftypeobjnearestto(x,y).objcanbeanobjectorthekeywordall.instance_furthest(x,y,obj)Returnstheidoftheinstanceoftypeobjfurthestawayfrom(x,y).objcanbeanobjectorthekeywordall.instance_place(x,y,obj)Returnstheidoftheinstanceoftypeobjmetwhenthecurrentinstanceisplacedatposition(x,y).objcanbeanobjectorthekeywordall.Ifitdoesnotexist,thespecialobjectnooneisreturned.

Thefollowingfunctionscanbeusedforcreatinganddestroyinginstances.

instance_create(x,y,obj)Createsaninstanceofobjatposition(x,y).Thefunctionreturnstheidofthenewinstance.instance_copy(performevent)Createsacopyofthecurrentinstance.Theargumentindicateswhetherthecreationeventmustbeexecutedforthecopy.Thefunctionreturnstheidofthenewcopy.instance_destroy()Destroysthecurrentinstance.instance_change(obj,perf)Changestheinstanceintoobj.perfindicateswhethertoperformthedestroyandcreationevents.position_destroy(x,y)Destroysallinstanceswhosespritecontainsposition(x,y).position_change(x,y,obj,perf)Changesallinstancesat(x,y)intoobj.perfindicateswhethertoperformthedestroyandcreationevents.

Deactivatinginstances

Pleasebeawarethatdeactivatingandactivatinginstancescansometimesleadtounexpectedproblems.Soyouarestronglyadvisednottousethisfeatureexceptforverysimplesituationliketheonesdescribedbelow.Thefeatureismainlyleftinforbackwardcompatibility.

Whenyoucreatelargeroom,forexampleinplatformgames,withasmallview,manyinstanceslieoutsidetheview.Suchinstancesthougharestillactiveandwillexecutetheirevents.Alsowhenperformingcollisioncheckstheseinstancesaretakenintoaccount.Thiscancostalotoftime,whichisoftennotnecessary.(Forexample,oftenitisnotimportantwhetherinstancesoutsidetheviewmove.)TosolvethisproblemGameMakercontainssomefunctionstodeactivateandactivateinstances.Beforeusingthemyoumustthoughclearlyunderstandhowtheywork.

Whenyoudeactivateinstancestheyareinsomesenseremovedfromthegame.Theyarenotvisibleanymorenorareanyeventsexecutedforthem.Soforallactionsandfunctionstheydon'texistanymore.Thissavesalotoftimebutyouhavetobecareful.Forexample,whenyoudeleteallinstancesofaparticulartype,deactivatedinstancesarenotdeleted(becausetheydon'texist).Sodon'tthinkthatakeyaplayerpicksupcanunlockadeactivateddoor.Alsopersistentdeactivatedinstancesarenotmovedovertothenextroom(eventhoughtheyarepersistent).Alsomakesurethatafteryoudeactivateaninstancethatyounolongerexecutecodeforit.Thiscaninparticularhappenwhenaninstancedeactivatesitself.Ingeneralyoubetterneverhaveaninstancedeactivateitself.

Themostcrucialmistakeyoucanmakeistodeactivatetheinstancethatisresponsiblefortheactivation.Toavoidthissomeoftheroutinesbelowallowyoutoinsistthatthecallinginstanceshouldnotbedeactivateditself.

Herearetheavailableroutines:

instance_deactivate_all(notme)Deactivatesallinstancesintheroom.Ifnotmeistruethecallinginstanceisnotdeactivated(whichisnormallywhatyouwant).instance_deactivate_object(obj)Deactivatesallinstancesintheroomofthegivenobject.Youcanalsousealltoindicatethatallinstancesmustbedeactivatedortheidofaninstancetodeactivateanindividualinstance.instance_deactivate_region(left,top,width,height,inside,notme)

Deactivatesallinstancesintheindicatedregion(thatis,thosewhoseboundingboxliespartiallyinsidetheregion).Ifinsideisfalsetheinstancescompletelyoutsidetheregionaredeactivated.Ifnotmeistruethecallinginstanceisnotdeactivated(whichisnormallywhatyouwant).instance_activate_all()Activatesallinstancesintheroom.instance_activate_object(obj)Activatesallinstancesintheroomofthegivenobject.Youcanalsousealltoindicatethatallinstancesmustbeactivatedortheidofaninstancetoactivateanindividualinstance.instance_activate_region(left,top,width,height,inside)Activatesallinstancesintheindicatedregion.Ifinsideisfalsetheinstancescompletelyoutsidetheregionareactivated.

Forexample,todeactivateallinstancesoutsidetheviewandactivatetheonesinsidetheview,youcouldplacethefollowingcodeinthestepeventofthemovingcharacter:

{

instance_activate_all();

instance_deactivate_region(view_xview[0],view_yview[0],

view_wview[0],view_hview[0],false,true);

}

Inpracticeyoumightwanttousearegionslightlylargerthantheview.

Timing

Goodgamesrequirecarefultimingofthingshappening.FortunatelyGameMakerdoesmostofthetimingforyou.Itmakessurethingshappenataconstantrate.Thisrateisdefinedwhendefiningtherooms.Butyoucanchangeitusingtheglobalvariableroom_speed.Soforexample,youcanslowlyincreasethespeedofthegame,makingitmoredifficult,byaddingaverysmallamount(like0.001)toroom_speedineverystep.Ifyourmachineisslowthegamespeedmightnotbeachieved.Thiscanbecheckedusingthevariablefpsthatconstantlymonitorstheactualnumberofframespersecond.Finally,forsomeadvancedtimingyoucanusethevariablecurrent_timethatgivesthenumberofmillisecondssincethecomputerwasstarted.Hereisthetotalcollectionofvariablesavailable(onlythefirstonecanbechanged):

room_speedSpeedofthegameinthecurrentroom(instepspersecond).fps*Numberofframesthatareactuallydrawnpersecond.current_time*Numberofmillisecondsthathavepassedsincethesystemwasstarted.current_year*Thecurrentyear.current_month*Thecurrentmonth.current_day*Thecurrentday.current_weekday*Thecurrentdayoftheweek(1=sunday,...,7=saturday).current_hour*Thecurrenthour.current_minute*Thecurrentminute.current_second*Thecurrentsecond.

Sometimesyoumightwanttostopthegameforashortwhile.Forthis,usethesleepfunction.

sleep(numb)Sleepsnumbmilliseconds.

Asyoushouldknow,everyinstancehas12differentalarmclocksthatyoucanset.Tochangethevalues(orgetthevalues)ofthedifferent

alarmclocksusethefollowingvariable:

alarm[0..11]Valueoftheindicatedalarmclock.(Notethatalarmclocksonlygetupdatedwhenthealarmeventfortheobjectcontainsactions!)

Wehaveseenthatforcomplextimingissuesyoucanusethetimelineresource.Eachinstancecanhaveatimelineresourceassociatedwithit.Thefollowingvariablesdealwiththis:

timeline_indexIndexofthetimelineassociatedwiththeinstance.Youcansetthistoaparticulartimelinetousethatone.Setitto-1tostopusingatimelinefortheinstance.Notethatthisdoesnotstartthetimeline.Forthisusethevariabletimeline_running.timeline_positionCurrentpositionwithinthetimeline.Youcanchangethistoskipcertainpartsortorepeatparts.timeline_speedNormally,ineachstepthepositioninthetimelineisincreasedby1.Youcanchangethisamountbysettingthisvariabletoadifferentvalue.Youcanuserealnumberslike0.5.Ifthevalueislargerthanone,severalmomentscanhappenwithinthesametimestep.Theywillallbeperformedinthecorrectorder,sonoactionswillbeskipped.Youcanalsouseanegativevaluetoletthetimelineplaybackwards.timeline_runningIndicateswhetherthetimelineisrunning(true)orpausedorstopped(false).Youcanchangethisvariabletorunorstopthetimeline.timeline_loopingIndicatedwhetherthetimelineislooping(true)ornot(false).Youcanchangethisvariabletoswitchloopingonoroff.

Rooms

Gamesworkinrooms.Eachroomhasanindexthatisindicatedbythenameoftheroom.Thecurrentroomisstoredinvariableroom.Youcannotassumethatroomsarenumberedinaconsecutiveorder.Soneveraddorsubtractanumberfromtheroomvariable.Insteadusethefunctionsandvariablesindicatedbelow.Soatypicalpieceofcodeyouwilluseis:

{

if(room!=room_last)

{

room_goto_next();

}

else

{

game_end();

}

}

Thefollowingvariablesandfunctionsexistthatdealwithrooms.

roomIndexofthecurrentroom;canbechangedtogotoadifferentroom,butyouhadbetterusetheroutinesbelow.room_first*Indexofthefirstroominthegame.room_last*Indexofthelastroominthegame.room_goto(numb)Gototheroomwithindexnumb.room_goto_previous()Gotothepreviousroom.room_goto_next()Gotothenextroom.room_restart()Restartthecurrentroom.room_previous(numb)Returntheindexoftheroombeforenumb(-1=none)butdon'tgothere.room_next(numb)Returntheindexoftheroomafternumb(-1=none).game_end()Endthegame.game_restart()Restartthegame.

Whencallingoneoftheabovefunctionstochangetheroomorendorrestartthegame,pleaserealizethatthischangedoesactuallynotoccuratthatprecisemoment.Itonlyhappensafterthecurrentactionisfullyexecuted.Sotherestofthescriptwillstillbeexecuted,andthesameappliestopossiblecallingscripts.However,noeventsareexecutedanymore.Asthiscanleadtounexpectedbehavioryouarestronglyadvisednottoputanycodeanymoreaftertheuseofsuchfunctions.

Roomshaveanumberofadditionalproperties:

room_width*Widthoftheroominpixels.room_height*Heightoftheroominpixels.room_captionCaptionstringfortheroomthatisdisplayedinthecaptionofthewindow.room_persistentWhetherthecurrentroomispersistent.

Manygamesoffertheplayerthepossibilityofsavingthegameandloadingasavedgame.InGameMakerthishappensautomaticallywhentheplayerpress<F5>forsavingand<F6>forloading.Youcanalsosaveandloadgamesfromwithinapieceofcode(notethatloadingonlytakesplaceattheendofthecurrentstep).

game_save(string)Savesthegametothefilewithnamestring.game_load(string)Loadsthegamefromthefilewithnamestring.

Pleaserealizethatonlythebasicgamedataisbeingsaved.Ifforexampleyouplayaparticularpieceofmusic,theprecisepositioninthemusicisnotsaved.Alsochangedresourcesarenotsaved.Otherthingsthatarenotsavedarethecontentsofdatastructures,particles,andmultiplayersettings.

Transitions

Whenyoumovefromoneroomtoanotheryoucanselectatransition.Tosetthetransitiontothenextframeyoumustsetthevariablecalledtransition_kind.Ifyouassignavaluelargerthan0toitthecorrespondingtransitionisusedforthenextroomtransition.Itonlyaffectthenexttransition.Afterthisthevalueisresetto0,whichindicatesnotransition.

transition_kindIndicatesthenextroomtransition.Youcanusethefollowingbuiltinvalues

0=noeffect1=Createfromleft2=Createfromright3=Createfromtop4=Createfrombottom5=Createfromcenter6=Shiftfromleft7=Shiftfromright8=Shiftfromtop9=Shiftfrombottom10=Interlacedfromleft11=Interlacedfromright12=Interlacedfromtop13=Interlacedfrombottom14=Pushfromleft15=Pushfromright16=Pushfromtop17=Pushfrombottom18=Rotatetotheleft19=Rotatetotheright20=Blendtherooms21=Fadeoutandin

transition_stepsIndicatesthenumberofstepsinthetransition.The

moresteps,thelongerthetransitiontakes.Defaultis80.transition_define(kind,name)Youcanactuallycreateyourowntransitions.Tothisendyoumustdefineascript(possiblyinanextensionpackage)todothetransition.Withthisfunctionyoucanthenaddthetransitiontothesystem.kindistheindexofthetransition(eitheranewoneoranexistingtransitions).nameisthenameofthescript.Notethatthenameofthescriptisastring!Sotheremustbequotesaroundit.Notethatthisisreallyadvancedstuff.Thescriptmusttakefivearguments:asurfacewiththeimageofthepreviousroom,asurfacewiththeimageofthenextroom,thewidthofthesurfaces,theheightofthesurfaces,andthefractionofthetransition(between0and1).Itmustthendrawtheimageusingthetwosurfaces.transition_exists(kind)Thisfunctionreturnswhetheratransitionoftheindicatedkindexists.

Pleasenotethattransitionsdonotworkwhenusingusing3dgraphics.Also,roomtransitionsingeneraldonotworkcorrectlywhenthesizesoftherooms(ortobemorepreciseoftheregiononthescreen)arenotthesame.

Score

Otherimportantaspectsofmanygamesarethescore,thehealth,andthenumberoflives.GameMakerkeepstrackofthescoreinaglobalvariablescoreandthenumberoflivesinaglobalvariablelives.Youcanchangethescorebysimplychangingthevalueofthisvariable.Thesameappliestohealthandlives.Iflivesislargerthan0andbecomessmallerthanorequalto0theno-more-liveseventisperformedforallinstances.Ifyoudon'twanttoshowthescoreandlivesinthecaption,setthevariableshow_score,etc.,tofalse.Alsoyoucanchangethecaption.Formorecomplicatedgamesbestdisplaythescoreyourself.

scoreThecurrentscore.livesNumberoflives.healthThecurrenthealth(0-100).show_scoreWhethertoshowthescoreinthewindowcaption.show_livesWhethertoshowthenumberoflivesinthewindowcaption.show_healthWhethertoshowthehealthinthewindowcaption.caption_scoreThecaptionusedforthescore.caption_livesThecaptionusedforthenumberoflives.caption_healthThecaptionusedforthehealth.

Generatingevents

Asyouknow,GameMakeriscompletelyeventdriven.Allactionshappenastheresultofevents.Thereareanumberofdifferentevents.Creationanddestroyeventshappenwhenaninstanceiscreatedordestroyed.Ineachstep,thesystemfirsthandlesthebeginstepevents.Nextithandlesthealarmevents,keyboardandmouseeventsandnextthestepevent.Afterthistheinstancesaresettotheirnewpositionsafterwhichthecollisioneventishandled.Finallytheendstepeventsarehandledafterwhichthedraweventisusedtodrawtheinstances(notethatwhentherearemultipleviewsthedraweventiscalledmultipletimesineachstep).Youcanalsoapplyaneventtothecurrentinstancefromwithinapieceofcode.Thefollowingfunctionsexist:

event_perform(type,numb)Performseventnumboftheindicatedtypetothecurrentinstance.Thefollowingeventtypescanbeindicated:

ev_createev_destroyev_step

ev_alarm

ev_keyboard

ev_mouse

ev_collision

ev_other

ev_draw

ev_keypress

ev_keyrelease

ev_trigger

Whentherearemultipleeventsofthegiventype,numbcanbeusedtospecifythepreciseevent.Fortheeventtypeev_alarmnumbcanrangefrom0to11.Fortheev_keyboard,ev_keypress.andev_keyreleaseeventtypesyouhavetousethekeycodeforthekey.Forev_mouseeventsyoucanusefornumbthefollowingconstants:

ev_left_button

ev_right_button

ev_middle_button

ev_no_button

ev_left_press

ev_right_press

ev_middle_press

ev_left_release

ev_right_release

ev_middle_release

ev_mouse_enter

ev_mouse_leave

ev_mouse_wheel_up

ev_mouse_wheel_down

ev_global_left_button

ev_global_right_button

ev_global_middle_button

ev_global_left_press

ev_global_right_press

ev_global_middle_press

ev_global_left_release

ev_global_right_release

ev_global_middle_release

ev_joystick1_left

ev_joystick1_right

ev_joystick1_up

ev_joystick1_down

ev_joystick1_button1








ev_joystick2_left

ev_joystick2_right

ev_joystick2_up

ev_joystick2_down









Forthecollisioneventyougivetheindexoftheotherobject.Forthe

eventtypeev_otheryoucanusefornumbthefollowingconstants:

ev_outside

ev_boundary

ev_game_start

ev_game_end

ev_room_start

ev_room_end

ev_no_more_lives

ev_no_more_health

ev_animation_end

ev_end_of_path

ev_close_button

ev_user0

ev_user1

ev_user2

ev_user3

ev_user4

ev_user5

ev_user6

ev_user7

ev_user8

ev_user9

ev_user10

ev_user11

ev_user12

ev_user13

ev_user14

ev_user15

Fortheev_stepeventtypeyoucanusethefollowingconstantsfornumb:

ev_step_normal

ev_step_begin

ev_step_end

Finallyfortheev_triggereventtypeyoushouldusetheconstantsthatyoucanspecifywhendefiningtheseevents.event_perform_object(obj,type,numb)Thisfunctionsworksthesameasthefunctionaboveexceptthatthistimeyoucanspecifyeventsinanotherobject.Notethattheactionsintheseeventsareappliedtothecurrentinstance,nottoinstancesofthegivenobject!event_user(numb)Intheothereventsyoucanalsodefine16user

events.Theseareonlyperformedifyoucallthisfunction.numbmustlieintherange0to15.event_inherited()Performstheinheritedevent.Thisonlyworksiftheinstancehasaparentobject.

Youcangetinformationaboutthecurrenteventbeingexecutedusingthefollowingread-onlyvariables:

event_type*Typeofthecurrenteventbeginexecuted.event_number*Numberofthecurrenteventbeginexecuted.event_object*Theobjectindexforwhichthecurrenteventisbeingexecuted.event_action*Theindexoftheactionthatiscurrentlybeingexecuted(0isthefirstintheevent,etc.).

Miscellaneousvariablesandfunctions

Herearesomevariablesandfunctionsthatdealwitherrors.

error_occurredIndicateswhetheranerrorhasoccurred.error_lastStringindicatingthelasterrormessage.show_debug_message(str)Showsthestringindebugmode.debug_modeThisread-onlyvariableindicateswhetherthegameisrunningindebugmode.

ThefollowingvariablescanbeusedtomakesureyourcodewillworkfortheappropriateversionandeditionofGameMaker.

gamemaker_proIndicateswhetherthegameiscreatedwiththeProEdition.gamemaker_registeredSameasgamemaker_progamemaker_versionTheversionofGameMaker.Thisisaninteger.Forversion8.0thiscanbeanythingbetween800and809.Forversion8.1thiswillbesomethingbetween810and819,etc.Sonevercheckaparticularversionbutbettercheckforarange.Thisvariableisnotavailableinversionbefore800.

Thefollowingfunctionsexistthatallowyoutocheckwhethercertainvariablesexistandwithwhichyoucansetvariablesandgettheirvalues.Inallthesefunctionsthevariablenameispassedasastring!

variable_global_exists(name)Returnswhetheraglobalvariablewiththegivenname(astring)exists.variable_local_exists(name)Returnswhetheralocalvariablewiththegivenname(astring)existsforthecurrentinstance.variable_global_get(name)Returnsthevalueoftheglobalvariablewiththegivenname(astring).variable_global_array_get(name,ind)Returnsthevalueofindexindoftheglobalarrayvariablewiththegivenname(astring).variable_global_array2_get(name,ind1,ind2)Returnsthevalueofindexind1,ind2oftheglobal2-dimensionalarrayvariablewiththe

givenname(astring).variable_local_get(name)Returnsthevalueofthelocalvariablewiththegivenname(astring).variable_local_array_get(name,ind)Returnsthevalueofindexindofthelocalarrayvariablewiththegivenname(astring).variable_local_array2_get(name,ind1,ind2)Returnsthevalueofindexind1,ind2ofthelocal2-dimensionalarrayvariablewiththegivenname(astring).variable_global_set(name,value)Setstheglobalvariablewiththegivenname(astring)tothegivenvalue.variable_global_array_set(name,ind,value)Setstheindexindintheglobalarrayvariablewiththegivenname(astring)tothegivenvalue.variable_global_array2_set(name,ind1,ind2,value)Setstheindexind1,ind2intheglobal2-dimensionalarrayvariablewiththegivenname(astring)tothegivenvalue.variable_local_set(name,value)Setsthelocalvariablewiththegivenname(astring)tothegivenvalue.variable_local_array_set(name,ind,value)Setstheindexindinthelocalarrayvariablewiththegivenname(astring)tothegivenvalue.variable_local_array2_set(name,ind1,ind2,value)Setstheindexind1,ind2inthelocal2-dimensionalarrayvariablewiththegivenname(astring)tothegivenvalue.

Forexample,youcanwrite:

{

ifvariable_global_exists('ammunition')

global.ammunition+=1

else

global.ammunition=0

}

Youcanalsousethesefunctionstopassvariablestoascriptinasortofby-referenceway,bypassingtheirnamesasstringsandusingthefunctionstochangethem.

Youcanchangetheprogrampriorityusingthefollowingfunction:

set_program_priority(priority)Setsthepriorityfortheprogram.Youcanindicateavaluebetween-3and+3.Avalueof-3meansthattheprogramwillonlyrunifnootherprocessonthecomputerrequiresprocessingtime,orstateddifferently,whenallotherprocessesareidle.Valuesof-2and-1arebelownormal,sootherprocesseswillgetpriority.0isthenormalvalue.+1and+2giveahigherpriority,resultingpossiblyinhigherspeedandsmoothergameflow.Butotherprocesseswillgetmuchlessprocessingtime.+3indicatesreal-timemode.Inreal-timemodebasicallyalltimeisallottedtothegame.Thiscanleadtoseriousproblemswithanyotherapplicationsrunningonthecomputer.Alsokeyboardeventsande.g.thepressingofthecloseboxmightnolongerberecordedbyWindows.Soonlyusethisifyouwantalltheprocessortime.Alsobettercheckcarefullybeforeusingitandsavethegamebeforerunning.

Finally,youcanusethefollowingfunctiontosetthetitleoftheapplication:

set_application_title(title)Setsthetitleoftheapplicationtothegivenstring.Thetitleisforexampleshowninthetaskbar.

Userinteraction

Thereisnogamewithoutinteractionwiththeuser.ThestandardwayofdoingthisinGameMakeristoputactionsinmouseorkeyboardevents.Butsometimesyouneedmorecontrol.Fromwithinapieceofcodeyoucancheckwhethercertainkeysonthekeyboardarepressedandyoucancheckforthepositionofthemouseandwhetheritsbuttonsarepressed.Normallyyouchecktheseaspectsinthestepeventofsomecontrollerobjectandtakeactionaccordingly.

Informationonuserinteractioncanbefoundinthefollowingpages:

TheKeyboardTheMouseTheJoystick

Thekeyboard

Forkeyboardinteraction,thefollowingvariablesandfunctionsexist:

keyboard_lastkeyKeycodeoflastkeypressed.Seebelowforkeycodeconstants.Youcanchangeit,e.g.setitto0ifyouhandledit.keyboard_keyKeycodeofcurrentkeypressed(seebelow;0ifnone).keyboard_lastcharLastcharacterpressed(asstring).keyboard_stringStringcontainingthelastatmost1024characterstyped.Thisstringwillonlycontaintheprintablecharacterstyped.Italsocorrectlyrespondstopressingthebackspacekeybyerasingthelastcharacter.

Sometimesitisusefultomaponekeytoanother.Forexampleyoumightwanttoallowtheplayertouseboththearrowkeysandthenumpadkeys.Ratherthanduplicatingtheactionsyoucanmapthenumpadkeystothearrowkeys.Alsoyoumightwanttoimplementamechanisminwhichtheplayercansetthekeystouse.Forthisthefollowingfunctionsareavailable:

keyboard_set_map(key1,key2)Mapsthekeywithkeycodekey1tokey2.keyboard_get_map(key)Returnsthecurrentmappingforkey.keyboard_unset_map()Resetsallkeystomaptothemselves.

Tocheckwhetheraparticularkeyormousebuttonispressedyoucanusethefollowingfunctions.Thisisinparticularusefulwhenmultiplekeysarepressedsimultaneously.

keyboard_check(key)Returnswhetherthekeywiththeparticularkeycodeiscurrentlydown.keyboard_check_pressed(key)Returnswhetherthekeywiththeparticularkeycodewaspressedsincethelaststep.keyboard_check_released(key)Returnswhetherthekeywiththeparticularkeycodewasreleasedsincethelaststep.

keyboard_check_direct(key)Returnswhetherthekeywiththeparticularkeycodeispressedbycheckingthehardwaredirectly.Theresultisindependentofwhichapplicationhasfocus.Itallowsforafewmorechecks.Inparticularyoucanusekeycodesvk_lshift,vk_lcontrol,vk_lalt,vk_rshift,vk_rcontrolandvk_ralttocheckwhethertheleftorrightshift,controloraltkeyispressed.

Thefollowingroutinescanbeusedtomanipulatethekeyboardstate:

keyboard_get_numlock()Returnswhetherthenumlockisset.keyboard_set_numlock(on)Sets(true)orunsets(false)thenumlock.keyboard_key_press(key)Simulatesapressofthekeywiththeindicatedkeycode.keyboard_key_release(key)Simulatesareleaseofthekeywiththeindicatedkeycode.

Thefollowingconstantsforvirtualkeycodesexist:

vk_nokeykeycoderepresentingthatnokeyispressedvk_anykeykeycoderepresentingthatanykeyispressedvk_leftkeycodeforleftarrowkeyvk_rightkeycodeforrightarrowkeyvk_upkeycodeforuparrowkeyvk_downkeycodefordownarrowkeyvk_enterenterkeyvk_escapeescapekeyvk_spacespacekeyvk_shiftshiftkeyvk_controlcontrolkeyvk_altaltkeyvk_backspacebackspacekeyvk_tabtabkeyvk_homehomekeyvk_endendkeyvk_deletedeletekeyvk_insertinsertkeyvk_pageuppageupkeyvk_pagedownpagedownkey

vk_pausepause/breakkeyvk_printscreenprintscreen/sysrqkeyvk_f1...vk_f12keycodesforthefunctionkeysF1toF12vk_numpad0...vk_numpad9numberkeysonthenumerickeypadvk_multiplymultiplykeyonthenumerickeypadvk_dividedividekeyonthenumerickeypadvk_addaddkeyonthenumerickeypadvk_subtractsubtractkeyonthenumerickeypadvk_decimaldecimaldotkeysonthenumerickeypad

Fortheletterkeysuseforexampleord('A').(Thecapitalletters.)Forthedigitkeysuseforexampleord('5')togetthe<5>key.Thefollowingconstantscanonlybeusedinkeyboard_check_direct:

vk_lshiftleftshiftkeyvk_lcontrolleftcontrolkeyvk_laltleftaltkeyvk_rshiftrightshiftkeyvk_rcontrolrightcontrolkeyvk_raltrightaltkey

Forexample,assumeyouhaveanobjectthattheusercancontrolwiththearrowkeysyoucanputthefollowingpieceofcodeinthestepeventoftheobject:

{

if(keyboard_check(vk_left))x-=4;

if(keyboard_check(vk_right))x+=4;

if(keyboard_check(vk_up))y-=4;

if(keyboard_check(vk_down))y+=4;

}

Ofcourseitisaloteasiertosimplyputthisinthekeyboardevents.

Therearesomeadditionalfunctionsrelatedtokeyboardinteraction.

keyboard_clear(key)Clearsthestateofthekey.Thismeansthatitwillnolongergeneratekeyboardeventsuntilitstartsrepeating.io_clear()Clearsallkeyboardandmousestates.

io_handle()Handleuserio,updatingkeyboardandmousestatus.keyboard_wait()Waitstilltheuserpressesakeyonthekeyboard.

Themouse

Formouseinteraction,thefollowingvariablesandfunctionsexist:

mouse_x*X-coordinateofthemouseintheroom.Cannotbechanged.mouse_y*Y-coordinateofthemouseintheroom.Cannotbechanged.mouse_buttonCurrentlypressedmousebutton.Asvalueusemb_none,mb_any,mb_left,mb_middle,ormb_right.mouse_lastbuttonLastpressedmousebutton.

Tocheckwhetheraparticularmousebuttonispressedyoucanusethefollowingfunctions.Thisisinparticularusefulwhenmultiplekeysarepressedsimultaneously.

mouse_check_button(numb)Returnswhetherthemousebuttoniscurrentlydown(useasvaluesmb_none,mb_left,mb_middle,ormb_right).mouse_check_button_pressed(numb)Returnswhetherthemousebuttonwaspressedsincethelaststep.mouse_check_button_released(numb)Returnswhetherthemousebuttonwasreleasedsincethelaststep.

Thefollowingfunctionscanbeusedtocheckwhetherthemousewheelwasused.

mouse_wheel_up()Returnswhetherthemousewheelwasmovedupsincethelaststep.mouse_wheel_down()Returnswhetherthemousewheelwasmoveddownsincethelaststep.

Therearesomeadditionalfunctionsrelatedtomouseinteraction.

mouse_clear(button)Clearsthestateofthemousebutton.Thismeansthatitwillnolongergeneratemouseeventsuntiltheplayer

releasesitandpressesitagain.io_clear()Clearsallkeyboardandmousestates.io_handle()Handleuserio,updatingkeyboardandmousestatus.mouse_wait()Waitstilltheuserpressesamousebutton.

Youcanchangethewaythemousecursorlookslike.Youcanchooseanyspriteforthis.Tothisendyoucanusethefollowingvariable:

cursor_spriteIndicatesthespritethatisusedtorepresentthecursor(defaultnospriteisused,representedbyavalueof-1).Youcanassignoneofthespritestothisvariabletohaveitbeendrawnautomaticallyatthepositionofthemousecursor.(YoucanalsoswitchoffthewindowsmousecursorintheGlobalGameSettings.)

Thejoystick

Therearesomeeventsassociatedwithjoysticks.Buttohavefullcontroloverthejoysticksthereisawholesetoffunctionstodealwithjoysticks.GameMakersupportsuptotwojoysticks.Soallofthesefunctionstakeajoystickidasargument.

joystick_exists(id)Returnswhetherjoystickid(1or2)exists.joystick_name(id)Returnsthenameofthejoystickjoystick_axes(id)Returnsthenumberofaxesofthejoystick.joystick_buttons(id)Returnsthenumberofbuttonsofthejoystick.joystick_has_pov(id)Returnswhetherthejoystickhaspoint-of-viewcapabilities.joystick_direction(id)Returnsthekeycode(vk_numpad1tovk_numpad9)correspondingtothedirectionofjoystickid(1or2).joystick_check_button(id,numb)Returnswhetherthejoystickbuttonispressed(numbintherange1-32).joystick_xpos(id)Returnstheposition(-1to1)ofthex-axisofjoystickid.joystick_ypos(id)Returnsthejoysticksy-position.joystick_zpos(id)Returnsthejoysticksz-position(ifithasaz-axis).joystick_rpos(id)Returnsthejoysticksrudderposition(orfourthaxis).joystick_upos(id)Returnsthejoysticksu-position(orfifthaxis).joystick_vpos(id)Returnsthejoysticksv-position(orsixthaxis).joystick_pov(id)Returnsthejoystickspoint-ofviewposition.Thisisananglebetween0and360degrees.0isforwards,90totheright,180backwardsand270totheleft.Whennopoint-of-viewdirectionispressedbytheuser-1isreturned.

Gamegraphics

Animportantpartofagameisthegraphics.GameMakernormallytakescareofmostofthisandforsimplegamesthereisneedtoworryaboutit.Butsometimesyouwanttotakemorecontrol.Forsomeaspectsthereareactionsbutfromcodeyoucancontrolmanymoreaspects.Thischapterdescribesallvariablesandfunctionsavailableforthisandgivessomemoreinformationaboutwhatisreallyhappening.

Informationongamegraphicscanbefoundinthefollowingpages:

SpritesandImagesBackgroundsDrawingSpritesandBackgroundsDrawingShapesFontsandTextAdvancedDrawingFunctionsDrawingSurfacesTilesTheDisplayTheWindowViewsRepaintingtheScreen

Spritesandimages

Eachobjecthasaspriteassociatedwithit.Thisiseitherasingleimageoritconsistsofmultipleimages.Foreachinstanceoftheobjecttheprogramdrawsthecorrespondingimageonthescreen,withitsorigin(asdefinedinthespriteproperties)attheposition(x,y)oftheinstance.Whentherearemultipleimages,itcyclesthroughtheimagestogetananimationeffect.Thereareanumberofvariablesthataffectthewaytheimageisdrawn.Thesecanbeusedtochangetheeffects.Eachinstancehasthefollowingvariables:

visibleIfvisibleistrue(1)theimageisdrawn,otherwiseitisnotdrawn.Invisibleinstancesarestillactiveandcreatecollisionevents;onlyyoudon'tseethem.Settingthevisibilitytofalseisusefulfore.g.controllerobjects(makethemnon-solidtoavoidcollisionevents)orhiddenswitches.sprite_indexThisistheindexofthecurrentspritefortheinstance.Youcanchangeittogivetheinstanceadifferentsprite.Asvalueyoucanusethenamesofthedifferentspritesyoudefined.Changingthespritedoesnotchangetheindexofthecurrentlyvisiblesubimage.sprite_width*Indicatesthewidthofthesprite.Thisvaluecannotbechangedbutyoumightwanttouseit.sprite_height*Indicatestheheightofthesprite.Thisvaluecannotbechangedbutyoumightwanttouseit.sprite_xoffset*Indicatesthehorizontaloffsetofthespriteasdefinedinthespriteproperties.Thisvaluecannotbechangedbutyoumightwanttouseit.sprite_yoffset*Indicatestheverticaloffsetofthespriteasdefinedinthespriteproperties.Thisvaluecannotbechangedbutyoumightwanttouseit.image_number*Thenumberofsubimagesforthecurrentspritefortheinstance(cannotbechanged).image_indexWhentheimagehasmultiplesubimagestheprogramcyclesthroughthem.Thisvariableindicatesthecurrentlydrawnsubimage(theyarenumberedstartingfrom0).Youcanchangethe

currentimagebychangingthisvariable.Theprogramwillcontinuecycling,startingatthisnewindex.(Thevaluecanhaveafractionalpart.Inthiscaseitisalwaysroundeddowntoobtainthesubimagethatisdrawn.)image_speedThespeedwithwhichwecyclethroughthesubimages.Avalueof1indicatesthateachstepwegetthenextimage.Smallervalueswillswitchsubimagesslower,drawingeachsubimagemultipletimes.Largervalueswillskipsubimagestomakethemotionfaster.Sometimesyouwantaparticularsubimagetobevisibleanddon'twanttheprogramtocyclethroughallofthem.Thiscanbeachievedbysettingthespeedto0andchoosingthecorrectsubimage.Forexample,assumeyouhaveanobjectthatcanrotateandyoucreateaspritethathassubimagesforanumberoforientations(counter-clockwise).Then,inthestepeventoftheobjectyoucanset

{

image_index=direction*image_number/360;

image_speed=0;

}

depthNormallyimagesaredrawnintheorderinwhichtheinstancesarecreated.Youcanchangethisbysettingtheimagedepth.Thedefaultvalueis0,unlessyousetittoadifferentvalueintheobjectproperties.Thehigherthevaluethefurthertheinstanceisaway.(Youcanalsousenegativevalues.)Instanceswithhigherdepthwillliebehindinstanceswithalowerdepth.Settingthedepthwillguaranteethattheinstancesaredrawnintheorderyouwant(e.g.theplaneinfrontofthecloud).Backgroundinstancesshouldhaveahigh(positive)depth,andforegroundinstancesshouldhavealow(negative)depth.image_xscaleAscalefactortomakelargerorsmallerimages.Avalueof1indicatesthenormalsize.Youmustseparatelysetthehorizontalxscaleandverticalyscale.Changingthescalealsochangesthevaluesfortheimagewidthandheightandinfluencescollisioneventsasyoumightexpect.Changingthescalecanbeusedtogeta3-Deffect.Youcanuseavalueof-1tomirrorthespritehorizontally.

image_yscaleTheverticalyscale.1isnoscaling.Youcanuseavalueof-1toflipthespritevertically.image_angleTheanglewithwhichthespriteisrotated.Youspecifythisindegrees,counterclockwise.Avalueof0indicatesnorotation.ThisvariablecanonlybesetintheProEdition!image_alphaTransparency(alpha)valuetousewhendrawingtheimage.Avalueof1isthenormalopaquesetting;avalueof0iscompletelytransparent.image_blendBlendingcolorusedwhendrawingthesprite.Avalueofc_whiteisthedefault.Whenyouspecifyadifferentvaluetheimageisblendedwiththiscolor.Thiscanbeusedtocolorizethespriteonthefly.ThisvariablecanonlybesetintheProEdition!bbox_left*Leftsideoftheboundingboxoftheinstanceintheroom,asdefinedbyitsimage(takingscalingintoaccount).bbox_right*Rightsideoftheboundingboxoftheinstanceintheroom.bbox_top*Topsideoftheboundingboxoftheinstanceintheroom.bbox_bottom*Bottomsideoftheboundingboxoftheinstanceintheroom.

Backgrounds

Eachroomcanhaveupto8backgrounds.Alsoithasabackgroundcolor.Allaspectsofthesebackgroundsyoucanchangeinapieceofcodeusingthefollowingvariables(notethatsomearearraysthatrangefrom0to7,indicatingthedifferentbackgrounds):

background_colorBackgroundcolorfortheroom.background_showcolorWhethertoclearthewindowinthebackgroundcolor.background_visible[0..7]Whethertheparticularbackgroundimageisvisible.background_foreground[0..7]Whetherthebackgroundisactuallyaforeground.background_index[0..7]Backgroundimageindexforthebackground.background_x[0..7]Xpositionofthebackgroundimage.background_y[0...7]Ypositionofthebackgroundimage.background_width[0...7]*Widthofthebackgroundimage.background_height[0...7]*Heightofthebackgroundimage.background_htiled[0..7]Whetherhorizontallytiled.background_vtiled[0..7]Whetherverticallytiled.background_xscale[0..7]Horizontalscalingfactorforthebackground.(Thismustbepositive;youcannotuseanegativevaluetomirrorthebackground.)background_yscale[0..7]Verticalscalingfactorforthebackground.(Thismustbepositive;youcannotuseanegativevaluetoflipthebackground.)background_hspeed[0..7]Horizontalscrollingspeedofthebackground(pixelsperstep).background_vspeed[0..7]Verticalscrollingspeedofthebackground(pixelsperstep).background_blend[0..7]Blendingcolortousewhendrawingthebackground.Avalueofc_whiteisthedefault.OnlyavailableintheProEdition!

background_alpha[0..7]Transparency(alpha)valuetousewhendrawingthebackground.Avalueof1isthenormalsetting;avalueof0iscompletelytransparent.

Drawingspritesandbackgrounds

Objectsnormallyhaveaspriteassociatedtoitthatisdrawn.Butyoucanusethedraweventtodrawotherthings.Thissectionandthenextcouplegiveyouinformationonwhatispossible.Firstofall,therearefunctionstodrawspritesandbackgroundsindifferentways.Thesegiveyoumorecontrolovertheappearanceofthesprite.Alsoyoucandraw(partsof)backgrounds.

draw_sprite(sprite,subimg,x,y)Drawssubimagesubimg(-1=current)ofthespritewithitsoriginatposition(x,y).(Withoutcolorblendingandnoalphatransparency.)draw_sprite_stretched(sprite,subimg,x,y,w,h)Drawsthespritestretchedsothatitfillstheregionwithtop-leftcorner(x,y)andwidthwandheighth.draw_sprite_tiled(sprite,subimg,x,y)Drawsthespritetiledsothatitfillstheentireroom.(x,y)istheplacewhereoneofthespritesisdrawn.draw_sprite_part(sprite,subimg,left,top,width,height,x,y)Drawstheindicatedpartofsubimagesubimg(-1=current)ofthespritewiththetop-leftcornerofthepartatposition(x,y).

draw_background(back,x,y)Drawsthebackgroundatposition(x,y).(Withoutcolorblendingandnoalphatransparency.)draw_background_stretched(back,x,y,w,h)Drawsthebackgroundstretchedtotheindicatedregion.draw_background_tiled(back,x,y)Drawsthebackgroundtiledsothatitfillstheentireroom.draw_background_part(back,left,top,width,height,x,y)Drawstheindicatedpartofthebackgroundwiththetop-leftcornerofthepartatposition(x,y).

Thefollowingfunctionsareextendedfunctionsoftheonesindicatedabove.TheseextendedversionscanonlybeusedintheProEdition!

draw_sprite_ext(sprite,subimg,x,y,xscale,yscale,rot,color,alpha)

Drawsthespritescaledwithfactorsxscaleandyscaleandrotatedcounterclockwiseoverrotdegrees.coloristheblendingcolor(usec_whitefornoblending)andalphaindicatesthetransparencyfactorwithwhichtheimagesismergedwithitsbackground.Avalueof0makesthespritecompletelytransparent.Avalueof1makesitcompletelysolid.Thisfunctioncancreategreateffect(forexamplepartiallytransparentexplosions).draw_sprite_stretched_ext(sprite,subimg,x,y,w,h,color,alpha)

Drawsthespritestretchedsothatitfillstheregionwithtop-leftcorner(x,y)andwidthwandheighth.coloristheblendingcolorandalphaindicatesthetransparencysetting.draw_sprite_tiled_ext(sprite,subimg,x,y,xscale,yscale,color,alpha)

Drawsthespritetiledsothatitfillstheentireroombutnowwithscalefactorsandacolorandtransparencysetting.draw_sprite_part_ext(sprite,subimg,left,top,width,height,x,y,xscale,yscale,color,alpha)

Drawstheindicatedpartofsubimagesubimg(-1=current)ofthespritewiththetop-leftcornerofthepartatposition(x,y)butnowwithscalefactorsandacolorandtransparencysetting.draw_sprite_general(sprite,subimg,left,top,width,height,x,y,xscale,yscale,rot,c1,c2,c3,c4,alpha)

Themostgeneraldrawingfunction.Itdrawstheindicatedpartofsubimagesubimg(-1=current)ofthespritewiththetop-leftcornerofthepartatposition(x,y)butnowwithscalefactors,arotationangle,acolorforeachofthefourvertices(top-left,top-right,bottom-right,andbottom-left),andanalphatransparencyvalue.Notethatrotationtakesplacearoundthetop-leftcornerofthepart.

draw_background_ext(back,x,y,xscale,yscale,rot,color,alpha)

Drawsthebackgroundscaledandrotatedwithblendingcolor(usec_whitefornoblending)andtransparencyalpha(0-1).draw_background_stretched_ext(back,x,y,w,h,color,alpha)Drawsthebackgroundstretchedtotheindicatedregion.coloristheblendingcolorandalphaindicatesthetransparencysetting.draw_background_tiled_ext(back,x,y,xscale,yscale,color,alpha)

Drawsthebackgroundtiledsothatitfillstheentireroombutnowwithscalefactorsandacolorandtransparencysetting.draw_background_part_ext(back,left,top,width,height,x,y,xscale,yscale,color,alpha)

Drawstheindicatedpartofthebackgroundwiththetop-leftcornerofthepartatposition(x,y)butnowwithscalefactorsandacolorand

transparencysetting.draw_background_general(back,left,top,width,height,x,y,xscale,yscale,rot,c1,c2,c3,c4,alpha)

Themostgeneraldrawingfunction.Itdrawstheindicatedpartofthebackgroundwiththetop-leftcornerofthepartatposition(x,y)butnowwithscalefactors,arotationangle,acolorforeachofthefourvertices(top-left,top-right,bottom-right,andbottom-left),andanalphatransparencyvalue.Notethatrotationtakesplacearoundthetop-leftcornerofthepart.

Drawingshapes

Thereisawholecollectionoffunctionsavailabletodrawdifferentshapes.Alsotherearefunctionstodrawtext(seenextsection).Youcanonlyusetheseinthedrawingeventofanobject;thesefunctionsingeneraldon'tmakeanysenseanywhereelseincode.Realizethatcollisionsbetweeninstancesaredeterminedbytheirsprites(ormasks)andnotbywhatyouactuallydraw.Thefollowingdrawingfunctionsexistthatcanbeusedtodrawbasicshapes.

draw_clear(col)Clearstheentireroominthegivencolor(noalphablending).draw_clear_alpha(col,alpha)Clearstheentireroominthegivencolorandalphavalue(inparticularusefulforsurfaces).draw_point(x,y)Drawsapointat(x,y)inthecurrentcolor.draw_line(x1,y1,x2,y2)Drawsalinefrom(x1,y1)to(x2,y2).draw_line_width(x1,y1,x2,y2,w)Drawsalinefrom(x1,y1)to(x2,y2)withwidthw.draw_rectangle(x1,y1,x2,y2,outline)Drawsarectangle.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_roundrect(x1,y1,x2,y2,outline)Drawsaroundedrectangle.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_triangle(x1,y1,x2,y2,x3,y3,outline)Drawsatriangle.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_circle(x,y,r,outline)Drawsacircleat(x,y)withradiusr.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_ellipse(x1,y1,x2,y2,outline)Drawsanellipse.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_set_circle_precision(precision)Setstheprecisionwithwhichcirclesaredrawn,thatis,thenumberofsegmentstheyconsistof.

Theprecisionmustliebetween4and64andmustbedividableby4.Thisisalsousedfordrawingellipsesandroundedrectangles.draw_arrow(x1,y1,x2,y2,size)Drawsanarrowfrom(x1,y1)to(x2,y2).sizeindicatesthesizeofthearrowinpixels.draw_button(x1,y1,x2,y2,up)Drawsabutton,upindicateswhetherup(1)ordown(0).draw_path(path,x,y,absolute)Withthisfunctionyoucandrawtheindicatedpathintheroomwithitsstartatposition(x,y).Ifabsoluteistruethepathisdrawnatthepositionwhereitwasdefinedandthevaluesofxandyareignored.draw_healthbar(x1,y1,x2,y2,amount,backcol,mincol,maxcol,direction,showback,showborder)

Withthisfunctionyoucandrawahealthbar(oranyotherbarthatindicatessomevalue,likee.g.thedamage).Theargumentsx1,y1,x2andy2indicatethetotalareaforthebar.amountindicatesthepercentageofthebarthatmustbefilled(mustliebetween0and100).backcolisthecolorofthebackgroundforthebar.mincolandmaxcolindicatethecolorwhentheamountis0and100respectively.Foranamountinbetweenthecolorisinterpolated.Soyoucaneasilymakeabarthatgoese.g.fromgreentored.Thedirectionisthedirectioninwhichthebarisdrawn.0indicatesthatthebarisanchoredattheleft,1attheright,2atthetopand3atthebottom.Finallyshowbackindicateswhetherabackgroundboxmustbeshownandshowborderindicatedwhethertheboxandbarshouldhaveablackborderline.

Mostoftheabovefunctionsusethecolorandalphasettingthatcanbechangedwithfollowingfunctions.

draw_set_color(col)Setsthedrawingcolortobeusedfromnowonfordrawingprimitives.draw_set_alpha(alpha)Setsthealphatransparencyvaluetobeusedfromnowonfordrawingprimitives.Shouldlieintherange0-1.0isfullytransparent,1isfullyopaque.draw_get_color()Returnsthedrawingcolorusedfordrawingprimitives.draw_get_alpha()Returnsthealphavalueusedfordrawingprimitives.

Awholerangeofpredefinedcolorsisavailable:

c_aqua

c_black

c_blue

c_dkgray

c_fuchsia

c_gray

c_green

c_lime

c_ltgray

c_maroon

c_navy

c_olive

c_orange

c_purple

c_red

c_silver

c_teal

c_white

c_yellow

Thefollowingfunctionscanhelpyoutocreatethecolorsyouwant.

make_color_rgb(red,green,blue)Returnsacolorwiththeindicatedred,green,andbluecomponents,wherered,greenandbluemustbevaluesbetween0and255.make_color_hsv(hue,saturation,value)Returnsacolorwiththeindicatedhue,saturationandvaluecomponents(eachbetween0and255).color_get_red(col)Returnstheredcomponentofthecolor.color_get_green(col)Returnsthegreencomponentofthecolor.color_get_blue(col)Returnsthebluecomponentofthecolor.color_get_hue(col)Returnsthehuecomponentofthecolor.color_get_saturation(col)Returnsthesaturationcomponentofthecolor.color_get_value(col)Returnsthevaluecomponentofthecolor.merge_color(col1,col2,amount)Returnsamergedcolorofcol1andcol2.Themergingisdeterminedbyamount.Avalueof0correspondstocol1,avalueof1tocol2,andvaluesinbetweentomergedvalues.

Thefollowingmiscellaneousfunctionsexist.

draw_getpixel(x,y)Returnsthecolorofthepixelcorrespondingtoposition(x,y)intheroom.Thisisnotveryfast,sousewithcare.screen_save(fname)Savesapngimageofthescreeninthegivenfilename.Usefulformakingscreenshots.screen_save_part(fname,x,y,w,h)Savespartofthescreeninthegivenpngfilename.

Fontsandtext

Ingamesyousometimesneedtodrawtexts.Todrawatextyouhavetospecifythefonttouse.Fontscanbedefinedbycreatingfontresources(eitherintheGameMakerprogramorusingthefunctionstocreateresources).Therearedifferentfunctionstodrawtextsindifferentway.Ineachfunctionyouspecifythepositionofthetextonthescreen.Therearetwofunctionstosetthehorizontalandverticalalignmentofthetextwithrespecttothatposition.

Fortextdrawingthefollowingfunctionsexist:

draw_set_font(font)Setsthefontthatwillbeusedwhendrawingtext.Use-1tosetthedefaultfont(Arial12).draw_set_halign(halign)Setsthehorizontalalignmentusedwhendrawingtext.Chooseoneofthefollowingconstantsasvalues:

fa_left

fa_center

fa_right

draw_set_valign(valign)Setstheverticalalignmentusedwhendrawingtext.Chooseoneofthefollowingconstantsasvalues:

fa_top

fa_middle

fa_bottom

draw_text(x,y,string)Drawsthestringatposition(x,y),usingthedrawingcolorandalpha.A#symbolorcarriagereturnchr(13)orlinefeedchr(10)areinterpretedasnewlinecharacters.Inthiswayyoucandrawmulti-linetexts.(Use\#togetthe#symbolitself.)draw_text_ext(x,y,string,sep,w)Similartothepreviousroutinebutyoucanspecifytwomorethings.Firstofall,sepindicatestheseparationdistancebetweenthelinesoftextinamultilinetext.Use-1togetthedefaultdistance.Usewtoindicatethewidthofthetextinpixels.Linesthatarelongerthanthiswidtharesplit-upatspaces

or-signs.Use-1tonotsplituplines.string_width(string)Widthofthestringinthecurrentfontasitwouldbedrawnusingthedraw_text()function.Canbeusedforpreciselypositioninggraphics.string_height(string)Heightofthestringinthecurrentfontasitwouldbedrawnusingthedraw_text()function.string_width_ext(string,sep,w)Widthofthestringinthecurrentfontasitwouldbedrawnusingthedraw_text_ext()function.Canbeusedforpreciselypositioninggraphics.string_height_ext(string,sep,w)Heightofthestringinthecurrentfontasitwouldbedrawnusingthedraw_text_ext()function.

Thefollowingroutinesallowyoutodrawscaledandrotatedtextandalsotousegradientcolorsontexts.ThesefunctionsareonlyavailableintheProEdition!

draw_text_transformed(x,y,string,xscale,yscale,angle)Drawsthestringatposition(x,y)inthesamewayasabove,butscaleithorizontallyandverticallywiththeindicatedfactorsandrotateitcounter-clockwiseoverangledegrees.draw_text_ext_transformed(x,y,string,sep,w,xscale,yscale,angle)

Combinesthefunctiondraw_text_extanddraw_text_transformed.Itmakesitpossibletodrawamulti-linetextrotatedandscaled.draw_text_color(x,y,string,c1,c2,c3,c4,alpha)Drawsthestringatposition(x,y)likeabove.Thefourcolorsspecifythecolorsofthetop-left,top-right,bottom-right,andbottom-leftcornerofthetext.alphaisthealphatransparencytobeused(0-1).draw_text_ext_color(x,y,string,sep,w,c1,c2,c3,c4,alpha)Similartodraw_text_ext()butwithcoloredvertices.draw_text_transformed_color(x,y,string,xscale,yscale,angle,c1,c2,c3,c4,alpha)

Similartodraw_text_transformed()butwithcoloredvertices.draw_text_ext_transformed_color(x,y,string,sep,w,xscale,yscale,angle,c1,c2,c3,c4,alpha)

Similartodraw_text_ext_transformed()butwithcoloredvertices.

Advanceddrawingfunctions


Above,anumberofbasicdrawingfunctionshavebeendescribed.Hereyoufindanumberofadditionalfunctionsthatofferyoualotmorepossibilities.Firstofalltherearefunctionstodrawshapeswithgradientcolors.Secondlytherearefunctionstodrawmoregeneralpolygons,andfinallythereisthepossibilitytodrawtexturemappedpolygons.

Thefollowingextendedversionsofthebasicdrawingfunctionsexist.eachofthemgetsextracolorparametersthatareusedthedeterminethecoloratdifferentvertices.Thestandarddrawingcolorisnotusedinthesefunctions.

draw_point_color(x,y,col1)Drawsapointat(x,y)inthegivencolor.draw_line_color(x1,y1,x2,y2,col1,col2)Drawsalinefrom(x1,y1)to(x2,y2),interpolatingthecolorbetweencol1andcol2.draw_line_width_color(x1,y1,x2,y2,w,col1,col2)Drawsalinefrom(x1,y1)to(x2,y2)withwidthwinterpolatingthecolorbetweencol1andcol2.draw_rectangle_color(x1,y1,x2,y2,col1,col2,col3,col4,outline)

Drawsarectangle.Thefourcolorsindicatedthecolorsatthetop-left,top-right,bottom-right,andbottom-leftvertex.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_roundrect_color(x1,y1,x2,y2,col1,col2,outline)Drawsaroundedrectangle.col1isthecolorinthemiddleandcol2thecolorattheboundary.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_triangle_color(x1,y1,x2,y2,x3,y3,col1,col2,col3,outline)

Drawsatriangle.Thethreecolorsarethecolorsofthethreeverticeswhichisinterpolatedoverthetriangle.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_circle_color(x,y,r,col1,col2,outline)Drawsacircleat(x,y)withradiusr.col1isthecolorinthemiddleandcol2thecoloratthe

boundary.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).draw_ellipse_color(x1,y1,x2,y2,col1,col2,outline)Drawsanellipse.col1isthecolorinthemiddleandcol2thecolorattheboundary.outlineindicateswhetheronlytheoutlinemustbedrawn(true)oritshouldbefilled(false).

Youcanalsodrawlargerprimitives.Thisworksslightlydifferent.Youbeginbyspecifyingtheprimitiveyouwanttodraw.Nextyouspecifytheverticesforit,andfinallyyouendtheprimitive,atwhichmomentitisdrawn.Therearesixtypesofprimitives:

pr_pointlistTheverticesareasetofpoints.pr_linelistTheverticesareasetoflinesegments.Eachpairofverticesformsalinesegment.Sotheremustbeanevensetofvertices.pr_linestripTheverticesformapolylinewiththefirstconnectedtothesecond,thesecondtothethird,etc.Thelastoneisnotconnectedtothefirstone.Youhavetospecifyanextracopyofthefirstvertexforthis.pr_trianglelistTheverticesareasetoftriangles.Eachtripleofverticesformsatriangle.Sothenumberofverticesmustbeamultipleof3.pr_trianglestripTheverticesagainformtrianglesbutthistimeitworksslightlydifferent.Thefirstthreeformthefirsttriangle.Thelasttwoofthesevertices,togetherwiththenextvertex,formthesecondtriangle,etc.Soeachnewvertexspecifiesanewtriangle,connectedtothepreviousone.pr_trianglefanSimilartoatrianglelistbutthistimethefirstvertexispartofallthetriangles.Again,eachnewvertexspecifiesanewtriangle,connectedtothepreviousvertexandthefirstvertex.

Thefollowingfunctionsexistfordrawingprimitives

draw_primitive_begin(kind)Startaprimitiveoftheindicatedkind.draw_vertex(x,y)Addvertex(x,y)totheprimitive,usingthecolorandalphavaluesetbefore.draw_vertex_color(x,y,col,alpha)Addvertex(x,y)totheprimitive,

withitsowncolorandalphavalue.Thisallowsyoutocreateprimitiveswithsmoothlychangingcolorandalphavalues.draw_primitive_end()Endthedescriptionoftheprimitive.Thisfunctionactuallydrawsit.

Finally,itispossibletodrawprimitivesusingspritesorbackgroundsastextures.Whenusingatexturetheimageisplacedontheprimitive,reshapingittofittheprimitive.Texturesareusedtoadddetailtoprimitives,e.g.abrickwall.Tousetexturesyoufirstmustobtaintheidofthetextureyouwanttouse.Forthisthefollowingfunctionsexist:

sprite_get_texture(spr,subimg)Returnstheidofthetexturecorrespondingtosubimagesubimgoftheindicatedsprite.background_get_texture(back)Returnstheidofthetexturecorrespondingtotheindicatedbackground.

Aselectedtexturemightnotyetbeinvideomemory.Thesystemwillputitthereonceyouneeditbutsometimesyouwanttodecidethisyourself.Forthisthefollowingtwofunctionsexist:

texture_preload(texid)Putsthetextureimmediatelyintovideomemory.texture_set_priority(texid,prio)Whenthereistoolittlevideomemorysomewillberemovedtemporarilytomakeroomforothersthatareneeded.Theoneswithlowestpriorityareremovedfirst.Default,allhavepriority0butyoucanchangethepriorityhere.(Usepositivevalues!)

Toaddtexturestoprimitivesyoumustspecifywhichpartsofthetexturesmustbeputwhereontheprimitive.Positionsinthetextureareindicatedwithvaluesbetween0and1butthereisaproblemhere.Sizesoftexturesmustbepowersof2(soe.g.32x32or64x64).Ifyouwanttousespritesorbackgroundastexturesyoubettermakesuretheyhavesuchasize.Ifnot,thetestwillbeblank.Tofindoutwhichpartofthetextureisactuallyusedyoucanusethefollowingtwofunctions.Theyreturnavaluebetween0and1thatindicatesthewidthorheightoftheactualpartofthetexturebeingused.Specifyingthisvalueastexturecoordinatewillindicatetherightorbottomsideofthetexture.

texture_get_width(texid)Returnsthewidthofthetexturewiththegivenid.Thewidthliesintherange0-1.texture_get_height(texid)Returnstheheightofthetexturewiththegivenid.Theheightliesintherange0-1.

Todrawtexturedprimitivesyouusethefollowingfunctions:

draw_primitive_begin_texture(kind,texid)Startaprimitiveoftheindicatedkindwiththegiventexture.draw_vertex_texture(x,y,xtex,ytex)Addvertex(x,y)totheprimitivewithposition(xtex,ytex)inthetexture,blendingwiththecolorandalphavaluesetbefore.xtexandytexshouldnormallyliebetween0and1butalsolargervaluescanbeused,leadingtoarepetitionofthetexture(seebelow).draw_vertex_texture_color(x,y,xtex,ytex,col,alpha)Addvertex(x,y)totheprimitivewithposition(xtex,ytex)inthetexture,blendingwithitsowncolorandalphavalue.draw_primitive_end()Endthedescriptionoftheprimitive.Thisfunctionactuallydrawsit.

Therearethreefunctionsthatinfluencehowtexturesaredrawn:

texture_set_interpolation(linear)Indicateswhethertouselinearinterpolation(true)orpickthenearestpixel(false).Linearinterpolationgivessmoothertexturesbutcanalsobeabitblurryandsometimescostsextratime.Thissettingalsoinfluencethedrawingofspritesandbackground.Defaultisfalse.(Thiscanalsobechangedintheglobalgamesettings.)texture_set_blending(blend)Indicateswhethertouseblendingwithcolorsandalphavalues.Switchingthisoffmightbefasteronoldhardware.Thissettingalsoinfluencethedrawingofspritesandbackground.Defaultistrue.texture_set_repeat(repeat)Indicateswhethertouserepeatthetexture.Thisworksasfollows.Asindicatedabovetexturecoordinateslieintherange0-1.Ifyouspecifyavaluelargerthan1,defaulttherestisnotdrawn.Bysettingrepeattotruethetextureisrepeated.Notethatspritesandbackgroundsarealwaysdrawnwithoutrepeating.Soonceyoudrawaspriteofbackgroundthis

valueisresettofalse.Defaultisfalse.

Therearetwomorefunctionthatarenotonlyusefulfordrawingtextures.Normallyprimitivesareblendedwiththebackgroundusingthealphavalue.Youcanactuallyindicatehowthismusthappen.Besidesthenormalmodeitispossibletoindicatethatthenewcolormustbeaddedtotheexistingcolororsubtractedfromtheexistingcolor.Thiscanbeusedtocreatee.g.spotlightsorshadows.Alsoitispossibletosortoftakethemaximumofthenewandexistingcolor.Thiscanavoidcertainsaturationeffectsthatyoucangetwithadding.Notethatbothsubtractingandmaximumdonottakethealphavaluefullyintoaccount.(DirectXdoesnotallowthis.)Soyoubettermakesuretheoutsideareaisblack.Therearetwofunctions.Thefirstoneonlygivesyouthefouroptionsdescribedabove.Thesecondfunctiongivesyoualotmorepossibilities.Youshouldexperimentabitwiththesettings.Ifusedeffectivelytheycanbeusedtocreatee.g.interestingexplosionorhaloeffects.

draw_set_blend_mode(mode)Indicateswhatblendmodetouse.Thefollowingvaluesarepossible:bm_normal,bm_add,bm_subtract,andbm_max.Don'tforgettoresetthemodetonormalafterusebecauseotherwisealsootherspritesandeventhebackgroundsaredrawnwiththenewblendmode.draw_set_blend_mode_ext(src,dest)Indicateswhatblendmodetouseforboththesourceanddestinationcolor.Thenewcolorissomefactortimesthesourceandanotherfactortimesthedestination.Thesefactorsaresetwiththisfunction.Tounderstandthis,thesourceanddestinationbothhaveared,green,blue,andalphacomponent.Sothesourceis(Rs,Gs,Bs,As)andthedestinationis(Rd,Gd,Bd,Ad).Allareconsideredtoliebetween0and1.Theblendfactorsyoucanchooseforsourceanddestinationare:

bm_zero:Blendfactoris(0,0,0,0).bm_one:Blendfactoris(1,1,1,1).bm_src_color:Blendfactoris(Rs,Gs,Bs,As).bm_inv_src_color:Blendfactoris(1–Rs,1–Gs,1–Bs,1–As).bm_src_alpha:Blendfactoris(As,As,As,As).bm_inv_src_alpha:Blendfactoris(1–As,1–As,1–As,1–As).bm_dest_alpha:Blendfactoris(Ad,Ad,Ad,Ad).

bm_inv_dest_alpha:Blendfactoris(1–Ad,1–Ad,1–Ad,1–Ad).bm_dest_color:Blendfactoris(Rd,Gd,Bd,Ad).bm_inv_dest_color:Blendfactoris(1–Rd,1–Gd,1–Bd,1–Ad).bm_src_alpha_sat:Blendfactoris(f,f,f,1);f=min(As,1–Ad).

Forexample,thenormalblendingmodesetsthesourceblendingtobm_src_alphaandthedestinationblendingtobm_inv_src_alpha.Don'tforgettoresetthemodetonormalafterusebecauseotherwisealsootherspritesandeventhebackgroundsaredrawnwiththenewblendmode.

Drawingtextureprimitivesisabitofworkbutcanleadtogreatresults.Youcanevenuseittomakefake3Dgames.

DrawingSurfaces


Incertainsituationsyoumightwanttopaintnotdirectlyonthescreenbutonacanvasthatcanthenlaterbeusedtopaintthingsonthescreen.Suchacanvasiscalledasurface.Forexample,youwanttolettheuserdrawonthescreen.Thepaintshouldnotbedrawnonthescreen(becauseitwillberemovedeachnextstep),butinsteadyouwanttodrawitonaseparatesurfacethatiscopiedontothescreenineachstep.Oryouwanttouseatexturethatchangesovertime.

Surfacesmakethisallpossible.Theyareactuallyrathersimpletouse.Youfirstcreateasurface.Nextyouindicatethatfurtherdrawingshouldhappenonthissurface.Fromthatmomentonalldrawingfunctionsoperateonthesurface.Onceyouaredoneyouresetthedrawingtargetandfurtherdrawinghappensonthescreenagain.Youcandrawthesurfaceonthescreeninmanydifferentwaysoruseitasatexture.Therearethoughafewthingsyoumustbeawareof.Seetheremarksattheend.

Thefollowingfunctionsexisttodealwithsurfaces

surface_create(w,h)Createsasurfaceoftheindicatedwidthandheight.Returnstheidofthesurface,whichmustbeusedinallfurthercalls.Notethatthesurfacewillnotbecleared.Thisistheresponsibilityoftheuser.(Setitasatargetandcalltheappropriateclearfunction.)surface_free(id)Freesthememoryusedbythesurface.surface_exists(id)Returnswhetherthesurfacewiththeindicatedidexists.

surface_get_width(id)Returnsthewidthofthesurface.surface_get_height(id)Returnstheheightofthesurface.surface_get_texture(id)Returnsthetexturecorrespondingtothesurface.Thiscanbeusedtodrawtexturedobjectswiththeimageof

thesurface.

surface_set_target(id)Setstheindicatedsurfaceasthedrawingtarget.Allsubsequentdrawinghappensonthissurface.Itresetstheprojectiontosimplycoverthesurface.surface_reset_target()Resetsthedrawingtargettothenormalscreen.

surface_getpixel(id,x,y)Returnsthecolorofthepixelcorrespondingtoposition(x,y)inthesurface.Thisisnotveryfast,sousewithcare.surface_save(id,fname)Savesapngimageofthesurfaceinthegivenfilename.Usefulformakingscreenshots.surface_save_part(id,fname,x,y,w,h)Savespartofthesurfaceinthegivenpngfilename.

draw_surface(id,x,y)Drawsthesurfaceatposition(x,y).(Withoutcolorblendingandnoalphatransparency.)draw_surface_stretched(id,x,y,w,h)Drawsthesurfacestretchedtotheindicatedregion.draw_surface_tiled(id,x,y)Drawsthesurfacetiledsothatitfillstheentireroom.draw_surface_part(id,left,top,width,height,x,y)Drawstheindicatedpartofthesurfacewithitsoriginatposition(x,y).draw_surface_ext(id,x,y,xscale,yscale,rot,color,alpha)Drawsthesurfacescaledandrotatedwithblendingcolor(usec_whitefornoblending)andtransparencyalpha(0-1).draw_surface_stretched_ext(id,x,y,w,h,color,alpha)Drawsthesurfacestretchedtotheindicatedregion.coloristheblendingcolorandalphaindicatesthetransparencysetting.draw_surface_tiled_ext(id,x,y,xscale,yscale,color,alpha)Drawsthesurfacetiledsothatitfillstheentireroombutnowwithscalefactorsandacolorandtransparencysetting.draw_surface_part_ext(id,left,top,width,height,x,y,xscale,yscale,color,alpha)

Drawstheindicatedpartofthesurfacewithitsoriginatposition(x,y)butnowwithscalefactorsandacolorandtransparencysetting.draw_surface_general(id,left,top,width,height,x,y,xscale,yscale,rot,c1,c2,c3,c4,alpha)

Themostgeneraldrawingfunction.Itdrawstheindicatedpartofthesurfacewithitsoriginatposition(x,y)butnowwithscalefactors,arotationangle,acolorforeachofthefourvertices(top-left,top-right,bottom-right,andbottom-left),andanalphatransparencyvalue.

surface_copy(destination,x,y,source)Copiesthesourcesurfaceatposition(x,y)inthedestinationsurface.(Withoutanyformofblending.)surface_copy_part(destination,x,y,source,xs,ys,ws,hs)Copiestheindicatedpartofthesourcesurfaceatposition(x,y)inthedestinationsurface.(Withoutanyformofblending.)

Notethattherearenofunctionstocopypartofthescreentoasurface.(Thisisimpossibleduetopossibleformatdifferencesbetweenthescreenandthesurfaces.)Ifthisisrequiredyoumustsetasurfaceasrendertargetandnextdrawtheroom.Youcanthenusethesurfacecopyingroutinestogetpartsofit.

Notethatyoucanalsocreatespritesandbackgroundsfromsurfaces.Seethesectiononchangingresourcesformoreinformation.

Somecaremustbetakenwhenusingthesefunctions.Inparticularpleasenoticethefollowing:

Youshouldneverchangethedrawingtargetwhileyouareactuallydrawingonthescreen,thatis,neveruseitindrawingevents.Thiswillcauseseriousproblemswiththeprojectionandviewport.Surfacesdonotworkcorrectlywith3Dmode.Youcanusethemwhilenotin3Dmode(bycallingd3d_end()beforeusingthem),butonceyoustart3Dmodeagainthesurfaceswillbedestroyed.Forreasonsofspeed,thesurfaceismaintainedinvideomemoryonly.Asaresult,youmightloosethesurfacewhene.g.thescreenresolutionchangesorthescreensaverpopsup.Surfaceswillnotbesavedwhensavingagame.

Tiles

Asyoushouldknowyoucanaddtilestorooms.Atileisapartofabackgroundresource.Tilesarejustvisibleimages.Theydonotreacttoeventsandtheydonotgeneratecollisions.Asaresult,tilesarehandledalotfasterthanobjects.Anythingthatdoesnotneedeventsorcollisionscanbestbedonethroughtiles.Also,oftenonebetterusesatileforthenicegraphicswhileasimpleobjectisusedtogeneratethecollisionevents.

Youactuallyhavemorecontrolovertilesthanyoumightthink.Youcanaddthemwhendesigningtheroombutyoucanalsoaddthemduringtherunningofthegame.Youcanchangetheirposition,andevenscalethemormakethempartiallytransparent.Atilehasthefollowingproperties:

background.Thebackgroundresourcefromwhichthetileistaken.left,top,width,height.Thepartofthebackgroundthatisused.x,y.Thepositionofthetopleftcornerofthetileintheroom.depth.Thedepthofthetile.Youcanchooseanydepthyoulike,makingtilesappearbetweenobjectinstances.visible.Whetherthetileisvisible.xscale,yscale.Eachtilecanbedrawnscaled(defaultis1).blend.Ablendingcolorusedwhendrawingthetile.alpha.Analphavalueindicatingtiletransparency.1=nottransparent,0=fullytransparent.

Tochangethepropertiesofaparticulartileyouneedtoknowitsid.Whenyouaddtileswhencreatingroomstheidisshownintheinformationbaratthebottom.Thereisalsoafunctiontofindtheidofatileataparticularposition.

Thefollowingfunctionsexistthatdealwithtiles:

tile_add(background,left,top,width,height,x,y,depth)Addsanewtiletotheroomwiththeindicatedvalues(seeabovefortheirmeaning).Thefunctionreturnstheidofthetilethatcanbeused

lateron.tile_delete(id)Deletesthetilewiththegivenid.tile_exists(id)Returnswhetheratilewiththegivenidexists.

tile_get_x(id)Returnsthex-positionofthetilewiththegivenid.tile_get_y(id)Returnsthey-positionofthetilewiththegivenid.tile_get_left(id)Returnstheleftvalueofthetilewiththegivenid.tile_get_top(id)Returnsthetopvalueofthetilewiththegivenid.tile_get_width(id)Returnsthewidthofthetilewiththegivenid.tile_get_height(id)Returnstheheightofthetilewiththegivenid.tile_get_depth(id)Returnsthedepthofthetilewiththegivenid.tile_get_visible(id)Returnswhetherthetilewiththegivenidisvisible.tile_get_xscale(id)Returnsthexscaleofthetilewiththegivenid.tile_get_yscale(id)Returnstheyscaleofthetilewiththegivenid.tile_get_background(id)Returnsthebackgroundofthetilewiththegivenid.tile_get_blend(id)Returnstheblendingcolorofthetilewiththegivenid.tile_get_alpha(id)Returnsthealphavalueofthetilewiththegivenid.

tile_set_position(id,x,y)Setsthepositionofthetilewiththegivenid.tile_set_region(id,left,top,width,height)Setstheregionofthetilewiththegivenidinitsbackground.tile_set_background(id,background)Setsthebackgroundforthetilewiththegivenid.tile_set_visible(id,visible)Setswhetherthetilewiththegivenidisvisible.tile_set_depth(id,depth)Setsthedepthofthetilewiththegivenid.tile_set_scale(id,xscale,yscale)Setsthescalingofthetilewiththegivenid.tile_set_blend(id,color)Setstheblendingcolorofthetilewiththegivenid.OnlyavailableintheProEdition!tile_set_alpha(id,alpha)Setsthealphavalueofthetilewiththegivenid.

Thefollowingfunctionsdealwithlayersoftiles,thatis,collectionsoftilesatthesamedepth.

tile_layer_hide(depth)Hidesalltilesattheindicateddepthlayer.tile_layer_show(depth)Showsalltilesattheindicateddepthlayer.tile_layer_delete(depth)Deletesalltilesattheindicateddepthlayer.tile_layer_shift(depth,x,y)Shiftsalltilesattheindicateddepthlayeroverthevectorx,y.Canbeusedtocreatescrollinglayersoftiles.tile_layer_find(depth,x,y)Returnstheidofthetilewiththegivendepthatposition(x,y).Whennotileexistsattheposition-1isreturned.Whenmultipletileswiththegivendepthexistatthepositionthefirstoneisreturned.tile_layer_delete_at(depth,x,y)Deletesthetilewiththegivendepthatposition(x,y).Whenmultipletileswiththegivendepthexistatthepositiontheyarealldeleted.tile_layer_depth(depth,newdepth)Changesthedepthofalltilesattheindicateddepthtothenewdepth.Withthisfunctionyoucanmovewholetilelayerstoanewdepth.

Thedisplay

Thedisplayrepresentsthewholeareaonthemonitor.Ithasasize(typically1024x768,or1280x1024),acolordepth,thatis,thenumberofbitsthatareusedtorepresentasinglepixel(typically16=HighColoror32=FullColor)andarefreshfrequency,thatis,thenumberoftimespersecondthedisplayisrefreshed(typicallybetween60and120).Thesesettingscannormallybechangedthoughthedisplayproperties.Forgamesthough,inparticularwhentheyruninfull-screenmode,itisimportanttobeabletochangethesesettings.AllthesesettingscanbeinitializedforthegameintheGameSettings.Foruseduringgameplaythefollowingfunctionsexist.Notethoughthatchangingthesettingsduringgameplaywillresultinatimedelayasthingshastoberebuilt.ThefunctionstosetthemodeareonlyavailableintheProEdition.

display_get_width()Returnsthewidthofthedisplayinpixels.display_get_height()Returnstheheightofthedisplayinpixels.display_get_colordepth()Returnsthecolordepthinbits.display_get_frequency()Returnstherefreshfrequencyofthedisplay.display_set_size(w,h)Setsthewidthandheightofthedisplayinpixels.Returnswhetherthiswassuccessful.(Realizethatonlycertaincombinationsareallowed.)display_set_colordepth(coldepth)Setsthecolordepth.Ingeneralonly16and32areallowedvalues.Returnswhethersuccessful.display_set_frequency(frequency)Setstherefreshfrequencyforthedisplay.Onlyfewfrequenciesareallowed.Typicallyyoucouldsetthisto60withasameroomspeedtogetsmooth60framespersecondmotion.Returnswhethersuccessful.display_set_all(w,h,frequency,coldepth)Setsallatonce.Use-1forvaluesyoudonotwanttochange.Returnswhethersuccessful.display_test_all(w,h,frequency,coldepth)Testswhethertheindicatedsettingsareallowed.Itdoesnotchangethesettings.Use-1forvaluesyoudonotwanttochange.Returnswhetherthesettingsareallowed.

display_reset()Resetsthedisplaysettingstotheoneswhentheprogramwasstarted.

Sometimesitisusefultogetinformationaboutthepositionofthemouseonthedisplayortochangethisposition.Forthisthefollowingfunctionsexist:

display_mouse_get_x()Returnsthex-coordinateofthemouseonthedisplay.display_mouse_get_y()Returnsthey-coordinateofthemouseonthedisplay.display_mouse_set(x,y)Setsthepositionofthemouseonthedisplaytotheindicatedvalues.

Thewindow

Theactualgamehappensinawindow.Thiswindowhasanumberofproperties,likewhetherithasaborder,whetheritisfullscreen,etc.NormallythesearesetintheGameSettings.Butyoucanchangethenduringthegame.Thefollowingfunctionsexistforthis:

window_set_visible(visible)Setswhetherthegamewindowisvisible.Clearlyyounormallywantthewindowtoremainvisibleduringthewholegame.Theprogramwillnotreceivekeyboardeventswhenthewindowisinvisible.window_get_visible()Returnswhetherthegamewindowisvisible.window_set_fullscreen(full)Setswhetherthewindowisshowninfullscreenmode.window_get_fullscreen()Returnswhetherthewindowisshowninfullscreenmode.window_set_showborder(show)Setswhethertheborderaroundthewindowisshown.(Infullscreenmodeitisnevershown.)window_get_showborder()Returnswhethertheborderaroundthewindowisshowninwindowedmode.window_set_showicons(show)Setswhetherthebordericons(iconize,maximize,close)areshown.(Infullscreenmodethesearenevershown.)window_get_showicons()Returnswhetherthebordericonsareshowninwindowedmode.window_set_stayontop(stay)Setswhetherthewindowmustalwaysstayontopofotherwindows.window_get_stayontop()Returnswhetherthewindowalwaysstaysontopofotherwindows.window_set_sizeable(sizeable)Setswhetherthewindowissizeablebytheplayer.(Theplayercanonlysizeitwhentheborderisshownandthewindowisnotinfullscreenmode.)window_get_sizeable()Returnswhetherthewindowissizeablebytheplayer.window_set_caption(caption)Setsthecaptionstringforthewindow.

Normallyyouspecifythiswhendefiningtheroomanditcanbechangedusingthevariableroom_caption.Sothisfunctionisnormallynotuseful,unlessyoudrawtheroomyourselfratherthanlettingGameMakerdoit.Thecaptionisonlyvisiblewhenthewindowhasaborderandwhenitisnotinfullscreenmode.window_get_caption()Returnsthewindowcaption.window_set_cursor(curs)Setsthemousecursorusedinthewindow.Youcanusethefollowingconstant:

cr_default

cr_none

cr_arrow

cr_cross

cr_beam

cr_size_nesw

cr_size_ns

cr_size_nwse

cr_size_we

cr_uparrow

cr_hourglass

cr_drag

cr_nodrop

cr_hsplit

cr_vsplit

cr_multidrag

cr_sqlwait

cr_no

cr_appstart

cr_help

cr_handpoint

cr_size_all

Inparticular,tohidethemousecursor,usecr_noneasvalue.window_get_cursor()Returnsthecursorusedinthewindow.window_set_color(color)Setsthecolorofthepartofthewindowthatisnotusedfordisplayingtheroom.window_get_color()Returnsthewindowcolor.window_set_region_scale(scale,adaptwindow)Ifthewindowislargerthantheactualroomnormallytheroomisdisplayedinaregioncenteredinthewindow.Itisthoughpossibletoindicatethatitmustbescaledtofillthewholeorpartofthewindow.Avalueof1isnoscaling.Ifyouuseavalueof0theregionwillbescaledtofillthe

wholewindow.Ifyousetittoanegativevalueitwillbescaledtothemaximalsizeinsidethewindowwhilemaintainingtheaspectratio(thisisoftenwhatyouwant).adaptwindowindicateswhetherthewindowsizemustbeadaptedifthescaledroomdoesnotfitin.Adaptingthewindowisonlyeffectivewhenthescalefactorispositive.window_get_region_scale()Returnsthescalefactorforthedrawingregion.

Thewindowhasapositiononthescreenandasize.(Whenwetalkaboutpositionandsizewealwaysmeantheclientpartofthewindowwithouttheborders.)Youcanchangethesealthoughyouhardlyeverdofromwithinyourgame.Normallytheyaredeterminedautomaticallyorbytheplayer.Thefollowingfunctionscanbeusedtochangethewindowpositionandsize.Notethatthesefunctionsdealwiththewindowedmode.Ifthewindowisinfullscreenmodetheycanstillbeusedbutwillonlyhaveeffectwhenswitchingfullscreenmodeoff.

window_set_position(x,y)Setsthepositionofthe(clientpartofthe)windowtotheindicatedposition.window_set_size(w,h)Setsthesizeofthe(clientpartofthe)windowtotheindicatedsize.Notethatistheindicatedsizeistoosmalltofitthedrawingregionitiskeptlargeenoughfortheregiontofitit.window_set_rectangle(x,y,w,h)Setsthepositionandsizeofthewindowrectangle.(Doesbothpreviousroutinesinonestep.)window_center()Centersthewindowonthescreen.window_default()Givesthewindowthedefaultsizeandposition(centered)onthescreen.window_get_x()Returnsthecurrentx-coordinateofthewindow.window_get_y()Returnsthecurrenty-coordinateofthewindow.window_get_width()Returnsthecurrentwidthofthewindow.window_get_height()Returnsthecurrentheightofthewindow.

Again,youprobablyneverwanttouseanyofthewindowpositioningfunctionsasGameMakertakescareoftheseautomatically.

Inrarecasesyoumightwanttoknowthepositionofthemousewithrespecttothewindow.(Normallyyoualwaysusethemousepositionwith

respecttotheroomorwithrespecttoaview.)Thefollowingfunctionsexistforthis.

window_mouse_get_x()Returnsthex-coordinateofthemouseinthewindow.window_mouse_get_y()Returnsthey-coordinateofthemouseinthewindow.window_mouse_set(x,y)Setsthepositionofthemouseinthewindowtotheindicatedvalues.

Views

Asyoushouldknowyoucandefineuptoeightdifferentviewswhendesigningrooms.Aviewisdefinedbyitsviewareaintheroomanditsviewportonthescreen(ortobepreciseinthedrawingregionwithinthewindow).Usingviewsyoucanshowdifferentpartsoftheroomatdifferentplacesonthescreen.Also,youcanmakesurethataparticularobjectalwaysstaysvisible.

Youcancontroltheviewsfromwithincode.Youcanmakeviewsvisibleandinvisibleandchangetheplaceorsizeoftheviewsinthedrawingregionorthepositionandsizeoftheviewintheroom(whichisinparticularusefulwhenyouindicatenoobjecttobevisible).Youcanchangethesizeofthehorizontalandverticalborderaroundthevisibleobject,andyoucanindicatewhichobjectmustremainvisibleintheviews.Thelatterisveryimportantwhentheimportantobjectchangesduringthegame.Forexample,youmightchangethemaincharacterobjectbasedonitscurrentstatus.Unfortunately,thisdoesmeanthatitisnolongertheobjectthatmustremainvisible.Thiscanberemediedbyonelineofcodeinthecreationeventofallthepossiblemainobjects(assumingthismusthappeninthefirstview):

{

view_object[0]=object_index;

}

Thefollowingvariablesexistthatinfluencetheview.All,exceptthefirsttwoarearraysrangingfrom0(thefirstview)to7(thelastview).

view_enabledWhetherviewsareenabledornot.view_current*Thecurrentlydrawnview(0-7).Usethisonlyinthedrawingevent.Youcanforexamplecheckthisvariabletodrawcertainthingsinonlyoneview.Variablecannotbechanged.view_visible[0..7]Whethertheparticularviewisvisibleonthescreen.

view_xview[0..7]Xpositionoftheviewintheroom.view_yview[0..7]Ypositionoftheviewintheroom.view_wview[0..7]Widthoftheviewintheroom.view_hview[0..7]Heightoftheviewintheroom.view_xport[0..7]X-positionoftheviewportinthedrawingregion.view_yport[0..7]Y-positionoftheviewportinthedrawingregion.view_wport[0..7]Widthoftheviewportinthedrawingregion.view_hport[0..7]Heightoftheviewportinthedrawingregion.view_angle[0..7]Rotationangleusedfortheviewintheroom(counter-clockwiseindegrees).view_hborder[0..7]Sizeofhorizontalborderaroundthevisibleobject(inpixels).view_vborder[0..7]Sizeofverticalborderaroundvisibleobject(inpixels).view_hspeed[0..7]Maximalhorizontalspeedoftheview.view_vspeed[0..7]Maximalverticalspeedoftheview.view_object[0..7]Objectwhoseinstancemustremainvisibleintheview.Iftherearemultipleinstancesofthisobjectonlythefirstoneisfollowed.Youcanalsoassignaninstanceidtothisvariable.Inthatcasetheparticularinstanceisfollowed.

Notethatthesizeoftheimageonthescreenisdecidedbasedonthevisibleviewsatthebeginningoftheroom.Ifyouchangeviewsduringthegame,theymightnolongerfitonthescreen.Thescreensizethoughisnotadaptedautomatically.Soifyouneedthisyouhavetodoityourself,usingthefollowingfunctions:

window_set_region_size(w,h,adaptwindow)Setthewidthandheightofthedrawingregioninthewindow.adaptwindowindicateswhetherthewindowsizemustbeadaptediftheregiondoesnotfitin.Thewindowsizewillalwaysbeadaptedifyouusefixedscaling.(Seethefunctionwindow_set_region_scale().)window_get_region_width()Returnsthecurrentwidthofthedrawingregion.window_get_region_height()Returnsthecurrentheightofthedrawingregion.

Inagameyouoftenneedthepositionofthemousecursor.Normallyyou

useforthisthevariablesmouse_xandmouse_y.Whentherearemultipleviews,thesevariablesgivethemousepositionwithrespecttotheviewthemouseisin.Sometimesthough,youmightneedthemousepositionwithrespecttoaparticularview,alsowhenitisoutsidethatview.Forthisthefollowingfunctionsexist.

window_view_mouse_get_x(id)Returnsthex-coordinateofthemousewithrespecttotheviewwithindexid.window_view_mouse_get_y(id)Returnsthey-coordinateofthemousewithrespecttotheviewwithindexid.window_view_mouse_set(id,x,y)Setsthepositionofthemousewithrespecttotheviewwithindexid.window_views_mouse_get_x()Returnsthex-coordinateofthemousewithrespecttotheviewitisin(sameasmouse_x).window_views_mouse_get_y()Returnsthey-coordinateofthemousewithrespecttotheviewitisin(sameasmouse_y).window_views_mouse_set(x,y)Setsthepositionofthemousewithrespecttothefirstviewthatisvisible.

Repaintingthescreen

Normallyattheendofeachsteptheroomisrepaintedonthescreen.Butinrarecircumstancesyouneedtorepainttheroomatothermoments.Thishappenswhenyourprogramtakesoverthecontrol.Forexample,beforesleepingalongtimearepaintmightbewanted.Also,whenyourcodedisplaysamessageandwantstowaitfortheplayertopressakey,youneedarepaintinbetween.Therearetwodifferentroutinestodothis.

screen_redraw()Redrawstheroombycallingalldrawevents.screen_refresh()Refreshesthescreenusingthecurrentroomimage(notperformingdrawingevents).

Tounderstandthesecondfunction,youwillneedtounderstandmorefullyhowdrawingworksinternally.Thereisinternallyanimageonwhichalldrawinghappens.Thisimageisnotvisibleonthescreen.Onlyattheendofastep,afteralldrawinghastakenplace,isthescreenimagereplacedbythisinternalimage.(Thisiscalleddoublebuffering.)Thefirstfunctionredrawstheinternalimageandthenrefreshesthescreenimage.Thesecondfunctiononlyrefreshestheimageonthescreen.

Nowyoushouldalsorealizewhyyoucannotusedrawingactionsorfunctionsinothereventsthandrawingevents.Theywilldrawthingsontheinternalimagebutthesewon'tbevisibleonthescreen.Andwhenthedrawingeventsareperformed,firsttheroombackgroundisdrawn,erasingallyoudrewontheinternalimage.Butwhenyouusescreen_refresh()afteryourdrawing,theupdatedimagewillbecomevisibleonthescreen.So,forexample,ascriptcandrawsometextonthescreen,calltherefreshfunctionandthenwaitfortheplayertopressakey,likeinthefollowingpieceofcode.

{

draw_text(room_width/2,100,'Pressanykeytocontinue.');

screen_refresh();

keyboard_wait();

}

Pleaserealizethat,whenyoudrawinanothereventthanthedrawingevent,youdrawsimplyontheimage,notinaview!Sothecoordinatesyouusearethesameasiftherearenoviews.Becarefulwhenusingthistechnique.Makesureyouunderstanditfirstandrealizethatrefreshingthescreentakessometime.

WhenyouaredrawingtheroomyourselfitcanbeusefultoNOTletitbedrawnautomaticatall.Forexample,youmightwanttodrawtheroomonlyevery5steps.Youcanusethefollowingfunctionsforthis:

set_automatic_draw(value)Indicateswhethertoautomaticallyredrawtheroom(true,default)ornot(false).

Finallythereisafunctionwithwhichyoucansetwhethertosynchronizethedrawingwiththerefreshfrequencyofthemonitor:

set_synchronization(value)Indicateswhethertosynchronizethedrawingwiththerefreshfrequencyofthemonitor.

Youcanalsoforceawaitforthenextverticalsynchronizationusingthefollowingfunction:

screen_wait_vsync()Waitsforthenextverticalsynchronizationofthemonitor.

Soundandmusic

Soundplaysacrucialroleincomputergames.Soundsareaddedtoyourgameintheformofsoundresources.Makesurethatthenamesyouusearevalidvariablenames.Asyouwillhaveseenyoucanindicatefourdifferenttypesofsound:normalsounds,backgroundmusic,3Dsounds,andsoundsthatmustbeplayedthroughthemediaplayer.

Normalsoundsareusedforsoundeffects.Ingeneralwavefilesareusedforthis.Manyofthemcanplayatthesamemoment(evenmultipleinstancesofthesamenormalsound).Youcanapplyallsortsofeffectstothem.

Backgroundmusictypicallyconsistofmidifilesbutsometimesalsowavefilesareused.Soundeffectscanbeappliedtoit.Theonlydifferencewithnormalsoundsisthatonlyonebackgroundmusiccanplayatanymoment.Ifyoustartonethecurrentoneisstopped.

3Dsoundsallowfor3Dsoundeffectswhichisdescribedbelow.Theyaremonosounds(waveormidi).

Finally,ifyouwanttouseanothersoundtype,inparticularmp3,thesecannotbeplayedthroughDirectX.Asaresultthenormalmediaplayermustbeusedforthis.Thisismuchmorelimited.Onlyonesoundcanplayatthesametime.Noeffectscanbeapplied(notevenvolumechanges)andthetimingfore.g.loopingsoundsispoor.Therecanalsobedelaysinplayingthesesounds.Youarestronglyencouragednottousethem.(Somecomputersmightalsonotsupportthem)

Informationonsoundandmusiccanbefoundinthefollowingpages:

BasicsoundfunctionsSpecialeffects3DmusicCDmusic

Basicsoundfunctions

Therearefivebasicfunctionsrelatedtosounds,twotoplayasound,onetocheckwhetherasoundisplaying,andtwotostopsounds.Mosttaketheindexofthesoundasargument.Thenameofthesoundrepresentsitsindex.Butyoucanalsostoretheindexinavariable,andusethat.

sound_play(index)Playstheindicatessoundonce.Ifthesoundisbackgroundmusicthecurrentbackgroundmusicisstopped.sound_loop(index)Playstheindicatessound,loopingcontinuously.Ifthesoundisbackgroundmusicthecurrentbackgroundmusicisstopped.sound_stop(index)Stopstheindicatessound.Iftherearemultiplesoundswiththisindexplayingsimultaneously,allwillbestopped.sound_stop_all()Stopsallsounds.sound_isplaying(index)Returnswhether(acopyof)theindicatedsoundisplaying.Notethatthisfunctionsreturnstruewhenthesoundactuallyplaysthroughthespeakers.Afteryoucallthefunctiontoplayasounditdoesnotimmediatelyreachthespeakerssothefunctionmightstillreturnfalseforawhile.Similar,whenthesoundisstoppedyoustillhearitforawhile(e.g.becauseofecho)andthefunctionwillstillreturntrue.

Itispossibletousefurthersoundeffects.Inparticularyoucanchangethevolumeandthepan,thatis,whetherthesoundcomesfromtheleftorrightspeaker.Inallthesecasesthevolumecanonlybereduced.Thesefunctionsdonotworkforfilesthatplaythroughthemediaplayer(likemp3files).

sound_volume(index,value)Changesthevolumefortheindicatedsound(0=low,1=high).sound_global_volume(value)Changestheglobalvolumeforallsounds(0=low,1=high).sound_fade(index,value,time)Changesthevolumefortheindicatedsoundtothenewvalue(0=low,1=high)duringtheindicatedtime(inmilliseconds).Thiscanbeusedtofadeoutorfadeinmusic.

sound_pan(index,value)Changesthepanfortheindicatedsound(-1=left,0=center,1=right).sound_background_tempo(factor)Changesthetempoofthebackgroundmusic(ifitisamidifile).factorindicatesthefactorwithwhichtomultiplythetempo.Soavalueof1correspondstothenormaltempo.Largervaluescorrespondtoafastertempo,smallervaluestoaslowertempo.Mustliebetween0.01and100.

Besidesmidiandwavefiles(andmp3file)thereisactuallyafourthtypeoffilethatcanbeplayed:directmusicfiles.Thesehavetheextension.sgt.Suchfilesthoughoftenrefertootherfilesdescribinge.g.bandorstyleinformation.Tofindthesefiles,thesoundsystemmustknowwheretheyarelocated.Tothisendyoucanusethefollowingfunctionstosetthesearchdirectoryforfiles.Notethoughthatyoumustaddthefilesyourself.GameMakerdoesnotautomaticallyincludesuchadditionalfiles.

sound_set_search_directory(dir)Setsthedirectoryinwhichdirectmusicfilesaretobefound.Thedirstringshouldnotinclucethefinalbackslash.

Soundeffects


Soundeffectscanbeusedtochangethewaysoundsandbackgroundmusicsounds.Realizethatsoundeffectsonlyapplytowavefilesandmidifiles,nottomp3files.Thissectiondescribesthefunctionsthatexistforusingandchangingsoundeffects.Realizethattousethesefunctionsyouneedtohaveagoodunderstandingofhowsoundandsynthesizerswork.Noexplanationofthedifferentparametersisgivenhere.Searchtheweborbooksforfurtherinformations.

Toapplyasoundeffecttoaparticularsoundyoucaneitherindicatethiswhendefiningthesoundresourceoryoucanusethefollowingfunction

sound_effect_set(snd,effect)Setsa(combinationof)soundeffect(s)fortheindicatedsound.effectcanbeanyofthefollowingvalues:

se_nonese_chorusse_echo

se_flanger

se_gargle

se_reverb

se_compressor

se_equalizer

Youcansetacombinationofeffectsbyaddingupthevalues.Soe.g.youcanuse

sound_effect_set(snd,se_echo+se_reverb);

togetacombinationofechoandreverbeffects.

Alleffectshavesomedefaultsettings.Youcanchangethesesettingsonceaneffecthasbeenappliedtoasound.Theorderhereiscrucial.Youfirstapplytheeffecttothesoundandnextsettheparametersforit.

Onceyoureapplyeffectstothesound,thesettingsaregoneandyouhavetosetthemagain.Notethatallparametersmustlieinaparticularrange,whichisindicatedbelow.Thefollowingfunctionsexistforchangingeffectparameters:

sound_effect_chorus(snd,wetdry,depth,feedback,frequency,wave,delay,phase)

Setstheparametersforthechoruseffectfortheindicatedsound.Thefollowingparameterscanbeset:

wetdryRatioofwet(processed)signaltodry(unprocessed)signal.(range:0to100,default50)depthPercentagebywhichthedelaytimeismodulatedbythelow-frequencyoscillator,inhundredthsofapercentagepoint.(range:0to100,default25)feedbackPercentageofoutputsignaltofeedbackintotheeffect'sinput.(range:-99to99,default0)frequencyFrequencyoftheLFO.(range:0to10,default0)waveWaveformoftheLFO.(0=triangle,1=wave,default1)delayNumberofmillisecondstheinputisdelayedbeforeitisplayedback.(range:0to20,default0)phasePhasedifferentialbetweenleftandrightLFOs.(range:0to4,default2)

sound_effect_echo(snd,wetdry,feedback,leftdelay,rightdelay,pandelay)

Setstheparametersfortheechoeffectfortheindicatedsound.Thefollowingparameterscanbeset:

wetdryRatioofwet(processed)signaltodry(unprocessed)signal.(range:0to100,default50)feedbackPercentagefedbackintoinput(range:0to100,default0)leftdelayDelayforleftchannel,inmilliseconds.(range:1to2000,default333)rightdelayDelayforrightchannel,inmilliseconds.(range:1to2000,default333)pandelayWhethertoswapleftandrightdelayswitheachsuccessiveecho.(0=don'tswap,1=swap,default0)

sound_effect_flanger(snd,wetdry,depth,feedback,frequency,wave,delay,phase)

Setstheparametersfortheflangereffectfortheindicatedsound.Thefollowingparameterscanbeset:

wetdryRatioofwet(processed)signaltodry(unprocessed)signal.(range:0to100,default50)depthPercentagebywhichthedelaytimeismodulatedbythelow-frequencyoscillator,inhundredthsofapercentagepoint.(range:0to100,default25)feedbackPercentageofoutputsignaltofeedbackintotheeffect'sinput.(range:-99to99,default0)frequencyFrequencyoftheLFO.(range:0to10,default0)waveWaveformoftheLFO.(0=triangle,1=wave,default1)delayNumberofmillisecondstheinputisdelayedbeforeitisplayedback.(range:0to20,default0)phasePhasedifferentialbetweenleftandrightLFOs.(range:0to4,default2)

sound_effect_gargle(snd,rate,wave)Setstheparametersforthegargleeffectfortheindicatedsound.Thefollowingparameterscanbeset:

rateRateofmodulation,inHertz.(range:1to1000,default1)waveShapeofthemodulationwave.(0=triangle,1=square,default0)

sound_effect_reverb(snd,gain,mix,time,ratio)Setstheparametersforthereverbeffectfortheindicatedsound.Thefollowingparameterscanbeset:

gainInputgainofsignal,indecibels(dB).(range:-96to0,default0)mixReverbmix,indB.(range:-96to0,default0)timeReverbtime,inmilliseconds.(range:0.001to3000,default1000)ratioFrequencyratio.(range:0.001to0.999,default0.001)

sound_effect_compressor(snd,gain,attack,release,threshold,ratio,delay)

Setstheparametersforthecompressoreffectfortheindicatedsound.Thefollowingparameterscanbeset:

gainOutputgainofsignalaftercompression.(range:-60to60,default0)attackTimebeforecompressionreachesitsfullvalue.(range:0.01to500,default0.01)releaseSpeedatwhichcompressionisstoppedafterinputdropsbelowthreshold.(range:50to3000,default50)thresholdPointatwhichcompressionbegins,indecibels.(range:-60to0,default-10)ratioCompressionratio.(range:1to100,default10)delayTimeafterthresholdisreachedbeforeattackphaseisstarted,inmilliseconds.(range:0to4,default0)

sound_effect_equalizer(snd,center,bandwidth,gain)Setstheparametersfortheequalizereffectfortheindicatedsound.Thefollowingparameterscanbeset:

centerCenterfrequency,inhertz.(range:80to16000)bandwidthBandwidth,insemitones.(range:1to36)gainGain.(range:-15to15)

3Dsound


3Dsoundsreferstosoundthathasaposition(andvelocity)withrespecttothelistener.Althoughitsmostprominentuseisin3Dgamesyoucanalsoeffectivelyuseitin2Dgames.Theideaisthatasoundhasapositioninspace.Inallfunctionsthelistenerisassumedtobeatposition(0,0,0).Thesystemcalculateshowthelistenerwouldhearthesoundandadaptitaccordingly.Theeffectisespeciallygoodwhenyouhaveagoodspeakersystembutisalreadyworksonsmallspeakers.

Besidesaposition,thesoundcanalsohasavelocity.Thisleadstowell-knowndopplereffectswhicharecorrectlymodelled.Finallythesoundcanhaveanorientationand,again,thesoundisadaptedaccordingly.

GameMakersupports3Dsoundoptionsthroughthefunctionsbelow.Theyonlyworkforsoundresourcesthatwereindicatedtobe3D.(Thedisadvantageisthat3Dsoundswillbemono,notstereo.)

sound_3d_set_sound_position(snd,x,y,z)Setsthepositionoftheindicatedsoundwithrespecttothelistenertotheindicatedpositioninspace.Valuesonthex-axisincreasefromlefttoright,onthey-axisfromdowntoup,andonthez-axisfromneartofar.Thevaluesaremeasuredinmeters.Thevolumewithwhichthesoundishearddependsonthismeasureinthesamewayasintherealworld.sound_3d_set_sound_velocity(snd,x,y,z)Setsthevelocityoftheindicatedsoundtotheindicatedvectorinspace.Pleasenotethatsettingthevelocitydoesnotmeanthatthepositionchanges.Thevelocityisonlyusedforcalculatingdopplereffects.Soifyouwanttomovethesoundyoumustyourselfchangethepositionofthesound.sound_3d_set_sound_distance(snd,mindist,maxdist)Setstheminimumdistanceatwhichthesounddoesnolongerincreaseinloudnessandthemaximumdistanceatwhichthesoundcannolongerbeheard.Sowhenthedistanceliesbetween0andtheminimumdistancethesoundisatmaximalamplitude.When

betweentheminimaldistanceandthemaximaldistancetheamplitudeslowlydecreasesuntileitherthemaximaldistanceisreachedorthesoundisanywaynolongeraudible.Defaulttheminimumdistanceis1meterandthemaximaldistanceis1billionmeters.sound_3d_set_sound_cone(snd,x,y,z,anglein,angleout,voloutside)

Normallysoundhasthesameamplitudeatagivendistanceinalldirections.Youcansetthesoundconetochangethisandmakesounddirectional.x,y,zspecifythedirectionofthesoundcone.angleinspecifiestheinsideangle.Ifthelistenerisinsidethisangleithearsthesoundatitsnormalvolume.angleoutspecifiestheoutsideangle.Whenthelistenerisoutsidethisthevolumeisindicatedwithvoloutside.Tobeprecise,voloutsideisanegativenumberthatindicatesthenumberofhundredsofdecibelthatmustbesubtractedfromtheinsidevolume.Betweentheinsideandoutsideanglethevolumegraduallydecreases.

CDmusic


TherearealsoanumberoffunctionsdealingwithplayingmusicfromaCD.

cd_init()Mustbecalledbeforeusingtheotherfunctions.ShouldalsobecalledwhenaCDischanged(orsimplyfromtimetotime).cd_present()ReturnswhetheraCDispresentinthedefaultCDdrive.cd_number()ReturnsthenumberoftracksontheCD.cd_playing()ReturnswhethertheCDisplaying.cd_paused()ReturnswhethertheCDispausedorstopped.cd_track()Returnsthenumberofthecurrenttrack(1=thefirst).cd_length()ReturnsthelengthofthetotalCDinmilliseconds.cd_track_length(n)ReturnsthelengthoftracknoftheCDinmilliseconds.cd_position()ReturnsthecurrentpositionontheCDinmilliseconds.cd_track_position()Returnsthecurrentpositioninthetrackbeingplayedinmilliseconds.cd_play(first,last)TellstheCDtoplaytracksfirstuntillast.IfyouwanttoplaythefullCDgive1and1000asarguments.cd_stop()Stopsplaying.cd_pause()Pausestheplaying.cd_resume()Resumestheplaying.cd_set_position(pos)SetsthepositionontheCDinmilliseconds.cd_set_track_position(pos)Setsthepositioninthecurrenttrackinmilliseconds.cd_open_door()OpensthedooroftheCDplayer.cd_close_door()ClosesthedooroftheCDplayer.

Thereisoneverygeneralfunctiontoaccessthemultimediafunctionalityofwindows.

MCI_command(str)ThisfunctionssendsthecommandstringtotheWindowsmultimediasystemusingtheMediaControlInterface(MCI).Itreturnsthereturnstring.Youcanusethistocontrolallsortsofmultimediadevices.SeetheWindowsdocumentationforinformationinhowtousethiscommand.ForexampleMCI_command('playcdaudiofrom1')playsaCD(afteryouhavecorrectlyinitializeditusingothercommands).Thisfunctionisonlyforadvanceduse!

Splashscreens,highscores,andotherpop-ups

Inthissectionwewilldescribeanumberoffunctionsthatcanbeusedtodisplaysplashscreenswithvideos,images,etc.,todisplaymessagesandaskquestionstotheplayer,andtoshowthehighscorelist.

Informationonsplashscreenandmessagescanbefoundinthefollowingpages:

SplashScreensPopupMessagesandQuestionsHighscoreList

Splashscreens


Manygameshaveso-calledsplashscreens.Thesescreensshowavideo,animage,orsometext.Oftentheyareusedatthebeginningofthegame(asanintro),thebeginningofalevel,orattheendofthegame(forexamplethecredits).InGameMakersuchsplashscreenswithtext,imagesorvideocanbeshownatanymomentduringthegame.

Defaultthesesplashscreensareshowninsidethegamewindow,butitisalsopossibletoshowtheminaseparatewindow.Thegameisinterruptedwhilethesplashscreenisshown.Theplayercanreturntothegamebypressingtheescapekeyorbyclickingwiththemouseinthewindow.(Thesesettingscanbechanged;seebelow.)

Thefollowingfunctionscanbeusedtodisplaythesplashscreens:

splash_show_video(fname,loop)Showsavideosplashscreen.fnameisthenameofthevideofile.Whetheraparticularmoviefileissupporteddependsonthedriversonthemachine.Typicallyyoucanuse.avi,.mpg,and.wmvfilesbutavoidspecialcodecs.Youbestputthisfileinthefolderofthegameyourselforinasubfolder.loopindicateswhethertoloopthevideo.splash_show_text(fname,delay)Showsatextsplashscreen.fnameisthenameofthetextfile.Youcaneitherdisplaystandardtextfiles(.txt)orrichtextfiles(.rtf).Onlypartoftherichtextfeaturesaretakenintoaccount.E.g.imagesandotherembeddedobjectsarenotshown.delayindicatesthedelayinmillisecondsbeforereturningtothegame.use0oranegativevaluetowaituntiltheplayerpressestheescapekeyorclickswiththemouseinthewindow.(Notethatnoscrollbarwillbeshownnoristhereanotherwaytoscrollthetext.Sothetextmustfitthewindow.)splash_show_image(fname,delay)Showsanimagesplashscreen.fnameisthenameoftheimagefile.Manyimagetypesaresupported(forexample.bmp,.jpg,.tif,and.wmf)butnoanimated

images.delayisthedelayinmillisecondsbeforereturningtothegame.splash_show_web(url,delay)Showsawebpagesplashscreen.urlistheurlofthewebpage(startingwithhttp://)oritisthefilenameforalocalhtmlfile.Notehoweverthatyoumustprovidethefullpathforthistowork.Soyoubeste.g.useasurlsomethinglikeworking_directory+"\index.html".delayisthedelayinmillisecondsbeforereturningtothegame.

Youcanchangethewaythesplashscreensaredisplayedusingthefunctionsbelow:

splash_set_main(main)Indicatedwhetherthesplashscreenmustbeshowninthemaingamewindow(true,default)orinaseparatewindow(false).splash_set_scale(scale)Setsthescalefactortobeusedwhendisplayingasplashvideoorimage.Whenusingavalueof0thescalefactorischosensuchthatthewindowisfilled(default).splash_set_cursor(vis)Setswhetherthecursorshouldbevisibleinthesplashscreen.Defaultitisvisible.Formoviesthecursorcannotbeswitchedoff.splash_set_color(col)Setsthecoloroftheareasurroundingtheimageorvideo.splash_set_caption(cap)Setsthecaptionforthesplashwindow.Thisonlyhaseffectwhenisaseparatesplashwindowisused.Defaulttheemptystringisused.splash_set_fullscreen(full)Indicateswhethertouseafullscreenwindowornot.Thisonlyhaseffectwhenisaseparatesplashwindowisused.Defaultanormalwindowisused.splash_set_border(border)Indicateswhetherthewindowshouldhaveaborder.Thisonlyhaseffectwhenisaseparatenormalsplashwindowisused.Defaultaborderisused.splash_set_size(w,h)Setsthesizeofthesplashwindow.Thisonlyhaseffectwhenisaseparatenormalsplashwindowisused.Defaultsizeis640x480.splash_set_position(x,y)Setsthepositionofthesplashwindow.Thisonlyhaseffectwhenisaseparatenormalsplashwindowis

used.DefaultWindowsdeterminestheposition.splash_set_adapt(adapt)Indicatedwhetherthesizeofthewindowmustbeadaptedtothescaledsizeofthevideoorimage.Thisonlyhaseffectwhenisaseparatesplashwindowisused.Defaultadaptistrue.splash_set_top(top)Indicateswhetherthewindowshouldstayontopofotherwindows.Thisonlyhaseffectwhenisaseparatesplashwindowisused.Defaultthevalueistrue.splash_set_interrupt(interrupt)Indicateswhetherthegameplayshouldbeinterruptedwhileshowingthesplashwindow.Thisonlyhaseffectwhenisaseparatesplashwindowisused.Defaultthevalueistrue.splash_set_stop_key(stop)IndicateswhethertostopthedisplayofthesplashscreenwhentheplayerpressedtheEscapekey.Defaultthevalueistrue.splash_set_stop_mouse(stop)Indicateswhethertostopthedisplayofthesplashscreenwhentheplayerpressedthemouseinsidethesplashscreen.Defaultthevalueistrue.splash_set_close_button(show)Indicateswhethertoshowaclosebuttoninthetoprightcornerofthesplashscreen.Thisisusefulwhenrunninggamesinfullscreenmodeorwithoutaborder.Defaultthevalueistrue.

Thereisoneparticulartypeofsplashinfo,whichisthegameinformationthattheusercanenterinGameMaker.Youcandisplayitusingthefollowingfunction.Youcanalsoloadaseparateinfofile.Thisiscloselyrelatedtothedisplayingofthetextsplashscreenbutthedisplayisgovernedbythesettingsprovidedwhendefiningthegameinformationandnotbythesettingsabove.Itisalsodisplayedinadifferentwindow,soitispossibletodisplayboththegameinformationandasplashscreenatthesamemoment.ThesefunctionsalsoworkintheLiteEdition.

show_info()Displaysthegameinformationwindow.load_info(fname)Loadsthegameinformationfromthefilenamedfname.Thisshouldbearichtextfile(.rtf).Thismakesitpossibletoshowdifferenthelpfilesatdifferentmoments.Notethatcontrarytothespashscreens,thisrtffilecannotcontainimages.

Pop-upmessagesandquestions

Anumberofotherfunctionsexisttopopupmessages,questions,amenuwithchoices,oradialoginwhichtheplayercanenteranumber,astring,orindicateacolororfilename:

show_message(str)Displaysadialogboxwiththestringasamessage.show_message_ext(str,but1,but2,but3)Displaysadialogboxwiththestringasamessageanduptothreebuttons.But1,but2andbut3containthebuttontext.Anemptystringmeansthatthebuttonisnotshown.Inthetextsyoucanusethe&symboltoindicatethatthenextcharactershouldbeusedasthekeyboardshortcutforthisbutton.Thefunctionreturnsthenumberofthebuttonpressed(0iftheuserpressestheEsckey).show_question(str)Displaysaquestion;returnstruewhentheuserselectsyesandfalseotherwise.get_integer(str,def)Askstheplayerinadialogboxforanumber.stristhemessage.defisthedefaultnumbershown.get_string(str,def)Askstheplayerinadialogboxforastring.stristhemessage.defisthedefaultvalueshown.message_background(back)Setsthebackgroundimageforthepop-upboxforanyofthefunctionsabove.backmustbeoneofthebackgroundsdefinedinthegame.Unfortunately,alphavaluesarenottakenintoaccount.However,iftheleft-bottompixelhasanalphavalueof0,allpixelswiththatcolorwillbeconsideredtransparent.message_alpha(alpha)Setsthealphatranslucenceforthepop-upboxforanyofthefunctionsabove.alphamustliebetween0(completelytranslucent)and1(nottranslucent)(onlyforWindows2000orlater).message_button(spr)Setsthespriteusedforthebuttonsinthepop-upbox.sprmustbeaspriteconsistingofthreeimages,thefirstindicatesthebuttonwhenitisnotpressedandthemouseisfaraway,thesecondindicatesthebuttonwhenthemouseisaboveitbutnotpressedandthethirdisthebuttonwhenitispressed.

Unfortunately,alphavaluesarenottakenintoaccount.However,iftheleft-bottompixelhasanalphavalueof0,allpixelswiththatcolorwillbeconsideredtransparent.message_text_font(name,size,color,style)Setsthefontforthetextinthepop-upbox.(ThisisanormalWindowsfont,notoneofthefontresourcesyoucanoutinyourgame!)styleindicatesthefontstyle(0=normal,1=bold,2=italic,and3=bold-italic).message_button_font(name,size,color,style)Setsthefontforthebuttonsinthepop-upbox.styleindicatesthefontstyle(0=normal,1=bold,2=italic,and3=bold-italic).message_input_font(name,size,color,style)Setsthefontfortheinputfieldinthepop-upbox.styleindicatesthefontstyle(0=normal,1=bold,2=italic,and3=bold-italic).message_mouse_color(col)Setsthecolorofthefontforthebuttonsinthepop-upboxwhenthemouseisaboveit.message_input_color(col)Setsthecolorforthebackgroundoftheinputfiledinthepop-upbox.message_caption(show,str)Setsthecaptionforthepop-upbox.showindicateswhetherabordermustbeshown(1)ornot(0)andstrindicatesthecaptionwhentheborderisshown.message_position(x,y)Setsthepositionofthepop-upboxonthescreen.Use-1,-1tocenterthebox.message_size(w,h)Fixesthesizeofthepop-upboxonthescreen.Ifyouchoose-1forthewidththewidthoftheimageisused.Ifyouchoose-1fortheheighttheheightiscalculatedbasedonthenumberoflinesinthemessage.show_menu(str,def)Showsapopupmenu.strindicatesthemenutext.Thisconsistsofthedifferentmenuitemswithaverticalbarbetweenthem.Forexample,str='menu0|menu1|menu2'.Whenthefirstitemisselecteda0isreturned,etc.Whentheplayerselectsnoitem,thedefaultvaluedefisreturned.show_menu_pos(x,y,str,def)Showsapopupmenuasinthepreviousfunctionbutatpositionx,yonthescreen.get_color(defcol)Askstheplayerforacolor.defcolisthedefaultcolor.IftheuserpressesCancelthevalue-1isreturned.get_open_filename(filter,fname)Askstheplayerforafilenametoopenwiththegivenfilter.Thefilterhastheform

'name1|mask1|name2|mask2|...'.Amaskcontainsthedifferentoptionswithasemicolonbetweenthem.*meansanystring.Forexample:'bitmaps|*.bmp;*.wmf'.IftheuserpressesCancelanempystringisreturned.get_save_filename(filter,fname)Asksforafilenametosavewiththegivenfilter.IftheuserpressesCancelanempystringisreturned.get_directory(dname)Asksforadirectory.dnameisthedefaultname.IftheuserpressesCancelanempystringisreturned.get_directory_alt(capt,root)Analternativewaytoaskforadirectory.captisthecaptiontobeshow.rootistherootofthedirectorytreetobeshown.Usetheemptystringtoshowthewholetree.IftheuserpressesCancelanempystringisreturned.show_error(str,abort)Displaysastandarderrormessage(and/orwritesittothelogfile).abortindicateswhetherthegameshouldabort.

Highscorelist

Onespecialpop-upisthehighscorelistthatismaintainedforeachgame.Thefollowingfunctionsexist:

highscore_show(numb)Showsthehighscoretable.numbisthenewscore.Ifthisscoreisgoodenoughtobeaddedtothelist,theplayercaninputaname.Use-1tosimpledisplaythecurrentlist.highscore_set_background(back)Setsthebackgroundimagetouse.backmustbetheindexofoneofthebackgroundresources.highscore_set_border(show)Setswhetherthehighscoreformmusthaveaborderornot.highscore_set_font(name,size,style)Setsthefontusedforthetextinthetable.(ThisisanormalWindowsfont,notoneofthefontresources.)Youspecifythename,sizeandstyle(0=normal,1=bold,2=italic,3=bold-italic).highscore_set_colors(back,new,other)Setsthecolorsusedforthebackground,thenewentryinthetable,andtheotherentries.highscore_set_strings(caption,nobody,escape)Changesthedifferentdefaultstringsusedwhenshowingthehighscoretable.captionisthecaptionoftheform.nobodyisthestringusedwhenthereisnobodyattheparticularrank.escapeisthestringatthebottomindicatingtopresstheescapekey.Youcaninparticularusethiswhenyourgameshoulduseadifferentlanguage.highscore_show_ext(numb,back,border,col1,col2,name,size)Showsthehighscoretablewithanumberofoptions(canalsobeachievedbyusinganumberofthepreviousfunctions).numbisthenewscore.Ifthisscoreisgoodenoughtobeaddedtothelist,theplayercaninputaname.Use-1tosimpledisplaythecurrentlist.backisthebackgroundimagetouse,borderindicateswhetherornottoshowtheborder.col1isthecolorforthenewentry,col2thecolorfortheotherentries.nameisthenameofthefonttouse,andsizeisthefontsize.highscore_clear()Clearsthehighscorelist.highscore_add(str,numb)Addsaplayerwithnamestrandscore

numbtothelist.highscore_add_current()Addsthecurrentscoretothehighscorelist.Theplayerisaskedtoprovideaname.highscore_value(place)Returnsthescoreofthepersononthegivenplace(1-10).Thiscanbeusedtodrawyourownhighscorelist.highscore_name(place)Returnsthenameofthepersononthegivenplace(1-10).draw_highscore(x1,y1,x2,y2)Drawsthehighscoretableintheroomintheindicatedbox,usingthecurrentfont.

Resources

InGameMakeryoucandefinevarioustypesofresources,likesprites,sounds,fonts,objects,etc.Inthischapteryouwillfindanumberoffunctionsthatgiveinformationabouttheresources.Inthenextchapteryoufindinformationonhowtomodifyandcreateresourcesonthefly.

Informationonresourcescanbefoundinthefollowingpages:

SpritesSoundsBackgroundsFontsPathsScriptsTimelinesObjectsRooms

Sprites

Thefollowingfunctionswillgiveyouinformationaboutasprite:

sprite_exists(ind)Returnswhetheraspritewiththegivenindexexists.sprite_get_name(ind)Returnsthenameofthespritewiththegivenindex.sprite_get_number(ind)Returnsthenumberofsubimagesofthespritewiththegivenindex.sprite_get_width(ind)Returnsthewidthofthespritewiththegivenindex.sprite_get_height(ind)Returnstheheightofthespritewiththegivenindex.sprite_get_xoffset(ind)Returnsthex-offsetofthespritewiththegivenindex.sprite_get_yoffset(ind)Returnsthey-offsetofthespritewiththegivenindex.sprite_get_bbox_left(ind)Returnstheleftsideoftheboundingboxofthespritewiththegivenindex.sprite_get_bbox_right(ind)Returnstherightsideoftheboundingboxofthespritewiththegivenindex.sprite_get_bbox_top(ind)Returnsthetopsideoftheboundingboxofthespritewiththegivenindex.sprite_get_bbox_bottom(ind)Returnsthebottomsideoftheboundingboxofthespritewiththegivenindex.

Incertainsituationsyoumightwanttosavethebitmapcorrespondingtoaparticularsubimageofthespritetoafile.Forthisthefollowingfunctionscanbeused:

sprite_save(ind,subimg,fname)Savessubimagesubimgofspriteindtothefilewiththenamefname.Thismustbea.pngfile.OnlyavailableintheProEdition.sprite_save_strip(ind,fname)Savesallsubimagesofspriteindasastriptothefilewiththenamefname.Thismustbea.pngfile.Only

availableintheProEdition.

Sounds

Thefollowingfunctionswillgiveyouinformationaboutasound:

sound_exists(ind)Returnswhetherasoundwiththegivenindexexists.sound_get_name(ind)Returnsthenameofthesoundwiththegivenindex.sound_get_kind(ind)Returnsthekindofthesoundwiththegivenindex(0=normal,1=background,2=3d,3=mmplayer).sound_get_preload(ind)Returnswhetherthesoundwiththegivenindexhaspreloadset.

Soundsusemanyresourcesandmostsystemscanstoreandplayonlyalimitednumberofsounds.Ifyoumakealargegameyouwouldliketohavemorecontroloverwhichsoundsareloadedinaudiomemoryatwhattimes.Youcanusetheswitchoffthepreloadoptionforsoundstomakesuresoundsareonlyloadedwhenused.Thisthoughhastheproblemthatyoumightgetasmallhiccupwhenthesoundisusedfirst.Also,soundsarenotautomaticallyunloadedwhenyoudon'tneedthemanymore.Formorecontrolyoucanusethefollowingfunctions.

sound_discard(index)Freestheaudiomemoryusedfortheindicatedsound.sound_restore(index)Restorestheindicatedsoundinaudiomemoryforimmediateplaying.

Backgrounds

Thefollowingfunctionswillgiveyouinformationaboutabackground:

background_exists(ind)Returnswhetherabackgroundwiththegivenindexexists.background_get_name(ind)Returnsthenameofthebackgroundwiththegivenindex.background_get_width(ind)Returnsthewidthofthebackgroundwiththegivenindex.background_get_height(ind)Returnstheheightofthebackgroundwiththegivenindex.

Incertainsituationsyoumightwanttosavethebitmapcorrespondingthebackgroundtoafile.Forthisthefollowingfunctioncanbeused:

background_save(ind,fname)Savesthebackgroundindtothefilewiththenamefname.Thismustbea.pngfile.OnlyavailableintheProEdition.

Fonts

Thefollowingfunctionswillgiveyouinformationaboutafont:

font_exists(ind)Returnswhetherafontwiththegivenindexexists.font_get_name(ind)Returnsthenameofthefontwiththegivenindex.font_get_fontname(ind)Returnsthefontnameofthefontwiththegivenindex.font_get_bold(ind)Returnswhetherthefontwiththegivenindexisbold.font_get_italic(ind)Returnswhetherthefontwiththegivenindexisitalic.font_get_first(ind)Returnstheindexofthefirstcharacterinthefontwiththegivenindex.font_get_last(ind)Returnstheindexofthelastcharacterinthefontwiththegivenindex.

Paths

Thefollowingfunctionswillgiveyouinformationaboutapath:

path_exists(ind)Returnswhetherapathwiththegivenindexexists.path_get_name(ind)Returnsthenameofthepathwiththegivenindex.path_get_length(ind)Returnsthelengthofthepathwiththegivenindex.path_get_kind(ind)Returnsthekindofconnectionsofthepathwiththegivenindex(0=straight,1=smooth).path_get_closed(ind)Returnswhetherthepathisclosedornot.path_get_precision(ind)Returnstheprecisionusedforcreatingsmoothedpaths.path_get_number(ind)Returnsthenumberofdefiningpointsforthepath.path_get_point_x(ind,n)Returnsthex-coordinateofthen'thdefiningpointforthepath.0isthefirstpoint.path_get_point_y(ind,n)Returnsthey-coordinateofthen'thdefiningpointforthepath.0isthefirstpoint.path_get_point_speed(ind,n)Returnsthespeedfactoratthen'thdefiningpointforthepath.0isthefirstpoint.path_get_x(ind,pos)Returnsthex-coordinateatpositionposforthepath.posmustliebetween0and1.path_get_y(ind,pos)Returnsthey-coordinateatpositionposforthepath.posmustliebetween0and1.path_get_speed(ind,pos)Returnsthespeedfactoratpositionposforthepath.posmustliebetween0and1.

Scripts

Thefollowingfunctionswillgiveyouinformationaboutascript:

script_exists(ind)Returnswhetherascriptwiththegivenindexexists.script_get_name(ind)Returnsthenameofthescriptwiththegivenindex.script_get_text(ind)Returnsthetextstringofthescriptwiththegivenindex.

Timelines

Thefollowingfunctionswillgiveyouinformationaboutatimeline:

timeline_exists(ind)Returnswhetheratimelinewiththegivenindexexists.timeline_get_name(ind)Returnsthenameofthetimelinewiththegivenindex.

Objects

Thefollowingfunctionswillgiveyouinformationaboutanobject:

object_exists(ind)Returnswhetheranobjectwiththegivenindexexists.object_get_name(ind)Returnsthenameoftheobjectwiththegivenindex.object_get_sprite(ind)Returnstheindexofthedefaultspriteoftheobjectwiththegivenindex.object_get_solid(ind)Returnswhethertheobjectwiththegivenindexisdefaultsolid.object_get_visible(ind)Returnswhethertheobjectwiththegivenindexisdefaultvisible.object_get_depth(ind)Returnsthedepthoftheobjectwiththegivenindex.object_get_persistent(ind)Returnswhethertheobjectwiththegivenindexispersistent.object_get_mask(ind)Returnstheindexofthemaskoftheobjectwiththegivenindex(-1ifishasnospecialmask).object_get_parent(ind)Returnsindexoftheparentobjectofobjectind(anegativevalueisreturnedifithasnoparent).object_is_ancestor(ind1,ind2)Returnswhetherobjectind2isanancestorofobjectind1.

Rooms

Thefollowingfunctionswillgiveyouinformationaboutaroom:

room_exists(ind)Returnswhetheraroomwiththegivenindexexists.room_get_name(ind)Returnsthenameoftheroomwiththegivenindex.

Notethat,becauseroomschangeduringtheplayingofthegame,thereareotherroutinestogetinformationaboutthecontentsofthecurrentroom.

Changingresources


Itispossibletocreatenewresourcesduringthegame.Alsoyoucanchangeexistingresources.Thischapterdescribesthepossibilities.Bewarnedthough.Changingresourceseasilyleadstoseriouserrorsinyourgames!!!Youmustfollowthefollowingruleswhenchangingresources:

Don'tchangeresourcesthatarebeingused.Thiswillleadtoerrors!Forexample,don'tchangeaspritethatisbeingusedbyaninstance.Whenyousavethegameduringplaying,addedandchangedresourcesareNOTstoredwiththesavegame.Soifyouloadthesavedgamelater,thesemightnotbethereanymore.Ingeneral,whenyoumanipulateresourcesyoucannolongerusethebuilt-insystemforloadingandsavinggames.Whenyourestartthegameduringplaying,thechangedresourcesareNOTrestoredtotheiroriginalshape.Ingeneral,whenyoumanipulateresourcesyoucannolongerusetheactionorfunctiontorestartthegame.Resourcemanipulationcanbeslow.Forexample,changingspritesorbackgroundsisrelativelyslow.Sodon'tuseitduringthegameplay.Creatingresourcesduringgameplay(inparticularspritesandbackground)easilyuseshugeamountofmemory.Sobeextremelycarefulwiththis.Forexample,ifyouhavea32frame128x128animatedspriteandyoudecidetocreate36rotatedcopiesofityouwilluseup36x32x128x128x4=72MBofmemory!Makesureyoudeleteresourcesyounolongerneed.Otherwisethesystemsoonrunsoutofmemory.

Ingeneral,youshouldnotchangeanyresourcesduringgameplay.Bettercreateandchangetheresourcesatthebeginningofthegameormaybeatthebeginningofaroom.

Informationonchangingresourcescanbefoundinthefollowingpages:

SpritesSoundsBackgroundsFontsPathsScriptsTimelinesObjectsRooms

Sprites

Thefollowingroutinesareavailableforchangingspriteproperties:

sprite_set_offset(ind,xoff,yoff)Setstheoffsetofthespritewiththegivenindex.

Thefollowingroutinescanbeusedtocreatenewspritesandtoremovethem.

sprite_duplicate(ind)Createsaduplicateofthespritewiththegivenindex.Itreturnstheindexofthenewsprite.Whenanerroroccurs-1isreturned.sprite_assign(ind,spr)Assignstheindicatedspritetospriteind.Sothismakesacopyofthesprite.Inthiswayyoucaneasilysetanexistingspritetoadifferent,e.g.newsprite.sprite_merge(ind1,ind2)Mergestheimagesfromspriteind2intospriteind1,addingthemattheend.Ifthesizesdon'tmatchthespritesarestretchedtofit.Spriteind2isnotdeleted!sprite_add(fname,imgnumb,removeback,smooth,xorig,yorig)Addstheimagestoredinthefilefnametothesetofspriteresources.Manydifferentimagefiletypescanbedealtwith.Whentheimageisnotagifimageitcanbeastripcontaininganumberofsubimagesforthespritenexttoeachother.Useimgnumbtoindicatetheirnumber(1forasingleimage).For(animated)gifimages,thisargumentisnotused;thenumberofimagesinthegiffileisused.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeedges.xorigandyorigindicatethepositionoftheorigininthesprite.Thefunctionreturnstheindexofthenewspritethatyoucanthenusetodrawitortoassignittothevariablesprite_indexofaninstance.Whenanerroroccurs-1isreturned.sprite_replace(ind,fname,imgnumb,removeback,smooth,xorig,yorig)

Sameasabovebutinthiscasethespritewithindexindisreplaced.Thefunctionreturnswhetheritissuccessful.sprite_add_sprite(fname)Addsthespritestoredthefilefnameto

thesetofspriteresources.Thefilemustbea.gmsprfilethatissavedinthespritepropertyforminGameMaker.Asthisfilecontainsallspritesettings,nofurtherargumentsarerequired.Thefunctionreturnstheindexofthenewspritethatyoucanthenusetodrawitortoassignittothevariablesprite_indexofaninstance.Whenanerroroccurs-1isreturned.sprite_replace_sprite(ind,fname)Sameasabovebutinthiscasethespritewithindexindisreplaced.Thefunctionreturnswhetheritissuccessful.sprite_create_from_screen(x,y,w,h,removeback,smooth,xorig,yorig)

Createsaspritebycopyingthegivenareafromthescreen.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeboundaries.Thismakesitpossibletocreateanyspriteyouwant.Drawtheimageonthescreenusingthedrawingfunctionsandnextcreateaspritefromit.(Ifyoudon'tdothisinthedrawingeventyoucanevendoitinsuchawaythatitisnotvisibleonthescreenbynotrefreshingthescreen.)Theotherparametersareasabove.Thefunctionreturnstheindexofthenewsprite.Aworkofcautionisrequiredhere.Eventhoughwespeakaboutthescreen,itisactuallythedrawingregionthatmatters.Thefactthatthereisawindowonthescreenandthattheimagemightbescaledinthiswindowdoesnotmatter.sprite_add_from_screen(ind,x,y,w,h,removeback,smooth)Addsanareaofthescreenasanextsubimagetothespritewithindexind.sprite_create_from_surface(id,x,y,w,h,removeback,smooth,xorig,yorig)

Createsaspritebycopyingthegivenareafromthesurfacewiththegivenid.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeboundaries.Thismakesitpossibletocreateanyspriteyouwant.Drawtheimageonthesurfaceusingthedrawingfunctionsandnextcreateaspritefromit.Thefunctionreturnstheindexofthenewsprite.Notethatalphavaluesaremaintainedinthesprite.sprite_add_from_surface(ind,id,x,y,w,h,removeback,smooth)Addsanareaofthesurfaceidasanextsubimagetothespritewithindexind.

sprite_delete(ind)Deletesthespritefrommemory,freeingthememoryused.

Thefollowingroutineexiststochangetheappearanceofasprite.

sprite_set_alpha_from_sprite(ind,spr)Changesthealpha(transparancy)valuesinthespritewithindexindusingtheintensityvaluesinthespritespr.Thiscannotbeundone.

Finally,youcanchangethecollisioncheckingmaskforthespritewiththefollowingroutine.Pleaserealizethatthisdoesnotworkcorrectlywhenaninstancewiththatspriteisalreadypresentintheroom.

sprite_collision_mask(ind,sepmasks,bboxmode,bbleft,bbright,bbtop,bbbottom,kind,tolerance)

Changesthecollisionmaskforthespritewithindexind.sepmasksindicateswhethertheremustbeseparatecollisionmasksforallsubimages.bboxmodeistheboundingboxmode(0=automatic,1=fullimage,2=userdefined).bbleft,bbright,bbtop,bbbottomindicatetheboundingboxincaseofuserdefinedboundingbox.Youcanuse0forallthesevaluesintheothercases.kindisthekindofmask(0=precise,1=boundingbox,2=disk,3=diamond).toleranceindicatesthetoleranceinthetransparencyvalue(0=notolerance,255=fulltolerance).

Sounds

Thefollowingroutinescanbeusedtocreatenewsoundsandtoremovethem.

sound_add(fname,kind,preload)Addsasoundresourcetothegame.fnameisthenameofthesoundfile.kindindicatesthekindofsound(0=normal,1=background,2=3d,3=mmplayer)preloadindicateswhetherthesoundshouldimmediatelybestoredinaudiomemory(trueorfalse).Thefunctionreturnstheindexofthenewsound,whichcanbeusedtoplaythesound.(-1ifanerroroccurred,e.g.thefiledoesnotexist).sound_replace(index,fname,kind,preload)Sameasthepreviousfunctionbutthistimeanewsoundisnotcreatedbuttheexistingsoundindexisreplaced,freeingtheoldsound.Returnswhethercorrect.sound_delete(index)Deletestheindicatedsound,freeingallmemoryassociatedwithit.Itcannolongerberestored.

Backgrounds

Thefollowingroutinescanbeusedtocreatenewbackgroundsandtoremovethem.

background_duplicate(ind)Createsaduplicateofthebackgroundwiththegivenindex.Itreturnstheindexofthenewbackground.Whenanerroroccurs-1isreturned.background_assign(ind,back)Assignstheindicatedbackgroundtobackgroundind.Sothismakesacopyofthebackground.background_add(fname,removeback,smooth)Addstheimagestoredinthefilefnametothesetofbackgroundresources.Manydifferenttypesofimagescanbedealtwith.Whentheimagehasanalphachannel,thisisusedfortransparency.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeboundaries.Thefunctionreturnstheindexofthenewbackgroundthatyoucanthenusetodrawitortoassignittothevariablebackground_index[0]tomakeitvisibleinthecurrentroom.Whenanerroroccurs-1isreturned.background_replace(ind,fname,removeback,smooth)Sameasabovebutinthiscasethebackgroundwithindexindisreplaced.Thefunctionreturnswhetheritissuccessful.Whenthebackgroundiscurrentlyvisibleintheroomitwilbereplacedalso.background_add_background(fname)Addsthebackgroundstoredthefilefnametothesetofbackgroundresources.Thefilemustbea.gmbckfilethatissavedinthebackgroundpropertyforminGameMaker.Asthisfilecontainsallbackgroundsettings,nofurtherargumentsarerequired.Thefunctionreturnstheindexofthenewbackgroundthatyoucanthenusetodrawitortoassignittothevariablebackground_index[0]tomakeitvisibleinthecurrentroom.Whenanerroroccurs-1isreturned.background_replace_background(ind,fname)Sameasabovebutinthiscasethebackgroundwithindexindisreplaced.Thefunctionreturnswhetheritissuccessful.Whenthebackgroundiscurrently

visibleintheroomitwilbereplacedalso.background_create_color(w,h,col)Createsabackgroundofthegivensizeandwiththegivencolor.Itreturnstheindexofthenewbackground.Whenanerroroccurs-1isreturned.background_create_gradient(w,h,col1,col2,kind)Createsagradientfilledbackgroundofthegivensize.col1andcol2indicatethetwocolors.kindisanumberbetween0and5indicatingthekindofgradient:0=horizontal1=vertical,2=rectangle,3=ellipse,4=doublehorizontal,5=doublevertical.Itreturnstheindexofthenewbackground.Whenanerroroccurs-1isreturned.background_create_from_screen(x,y,w,h,removeback,smooth)

Createsabackgroundbycopyingthegivenareafromthescreen.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeboundaries.Thisfunctionmakesitpossibletocreateanybackgroundyouwant.Drawtheimageonthescreenusingthedrawingfunctionsandnextcreateabackgroundfromit.(Ifyoudon'tdothisinthedrawingeventyoucanevendoitinsuchawaythatitisnotvisibleonthescreenbynotrefreshingthescreen.)Thefunctionreturnstheindexofthenewbackground.Aworkofcautionisrequiredhere.Eventhoughwespeakaboutthescreen,itisactuallythedrawingregionthatmatters.Thefactthatthereisawindowonthescreenandthattheimagemightbescaledinthiswindowdoesnotmatter.background_create_from_surface(id,x,y,w,h,removeback,smooth)

Createsabackgroundbycopyingthegivenareafromthesurfacewiththegivenid.removebackindicateswhethertomakeallpixelswiththebackgroundcolor(left-bottompixel)transparent.smoothindicateswhethertosmooththeboundaries.Thisfunctionmakesitpossibletocreateanybackgroundyouwant.Drawtheimageonthesurfaceusingthedrawingfunctionsandnextcreateabackgroundfromit.Notethatalphavaluesaremaintainedinthebackground.background_delete(ind)Deletesthebackgroundfrommemory,freeingthememoryused.

Thefollowingroutineexiststochangetheappearanceofabackground.

background_set_alpha_from_background(ind,back)Changesthe

alpha(transparancy)valuesinthebackgroundwithindexindusingtheintensityvaluesinthebackgroundback.Thiscannotbeundone.

Fonts

Itispossibletocreate,replace,anddeletefontsduringthegameusingthefollowingfunctions.(Don'treplaceafontthatissetasthecurrentfontoratleastsetitagainafterwards.)

font_add(name,size,bold,italic,first,last)Addsanewfontandreturnsitsindex,indicatingthename,size,whetheritisboldoritalic,andthefirstandlastcharacterthatmustbecreated.font_add_sprite(spr,first,prop,sep)Addsanewfontandreturnsitsindex.Thefontiscreatedfromasprite.Thespriteshouldcontainasubimageforeachcharacter.firstindicatetheindexofthefirstcharacterinthesprite.Forexample,useord('0')ifyourspriteonlycontainsthedigits.propindicateswhetherthefontisproportional.Inaproportionalfont,foreachcharacterthewidthoftheboundingboxisusedasthecharacterwidth.Finally,sepindicatestheamountofwhitespacethatmustseparatethecharactershorizontally.Atypicalvaluewouldliebetween2and8dependingonthefontsize.font_replace(ind,name,size,bold,italic,first,last)Replacesthefontindwithanewfont,indicatingthename,size,whetheritisboldoritalic,andthefirstandlastcharacterthatmustbecreated.font_replace_sprite(ind,spr,first,prop,sep)Replacesthefontindwithanewsprite-basedfont.font_delete(ind)Deletesthefontwiththegivenindex,freeingthememoryituses.

Paths

Itispossibletocreatepathsandtoaddpointstopaths.However,neverchangeapaththatisbeingusedbyaninstance.Thiscanleadtounexpectedresults.Thefollowingfunctionsexist:

path_set_kind(ind,val)Setsthekindofconnectionsofthepathwiththegivenindex(0=straight,1=smooth).path_set_closed(ind,closed)Setswhetherthepathmustbeclosed(true)oropen(false).path_set_precision(ind,prec)Setstheprecisionwithwhichthesmoothpathiscalculated(shouldliebetween1and8).path_add()Addsanewemptypaths.Theindexofthepathisreturned.path_delete(ind)Deletesthepathwiththegivenindex.path_duplicate(ind)Createsaduplicatecopyofthepathwiththegivenindex.Returnstheindexofthecopy.path_assign(ind,path)Assignstheindicatedpathtopathind.Sothismakesacopyofthepath.Inthiswayyoucaneasilysetanexistingpathtoadifferent,e.g.newpath.path_append(ind,path)Appendstheindicatedpathtopathind.path_add_point(ind,x,y,speed)Addsapointtothepathwiththegivenindex,atposition(x,y)andwiththegivenspeedfactor.Rememberthatafactorof100correspondstotheactualspeed.Lowervaluesmeanslowingdownandhighermeanspeedingup.path_insert_point(ind,n,x,y,speed)Insertsapointinthepathwiththegivenindexbeforepointn,atposition(x,y)andwiththegivenspeedfactor.path_change_point(ind,n,x,y,speed)Changesthepointninthepathwiththegivenindextoposition(x,y)andthegivenspeedfactor.path_delete_point(ind,n)Deletesthepointninthepathwiththegivenindex.path_clear_points(ind)Clearsallthepointsinthepath,turningitintoanemptypath.path_reverse(ind)Reversesthepath.

path_mirror(ind)Mirrorsthepathhorizontally(withrespecttoitscenter).path_flip(ind)Flipsthepathvertically(withrespecttoitscenter).path_rotate(ind,angle)Rotatesthepathcounterclockwiseoverangledegrees(arounditscenter).path_scale(ind,xscale,yscale)Scalesthepathwiththegivenfactors(fromitscenter).path_shift(ind,xshift,yshift)Shiftsthepathoverthegivenamount.

Scripts

Scriptscannotbechangedduringtheexecutionofthegame.Thescriptsarepartofthegamelogic.Changingscriptswouldleadtoself-rewritingcodewhichveryeasilyleadstoerrors.Alsothereareotherwaystoachievethis.Ifyoureallyneedtoexecuteapieceofcodethatisnotknownatdesigntime(e.g.fromafile)youcanusethefollowingfunctions:

execute_string(str,arg0,arg1,...)Executethepieceofcodeinthestringstrwiththeindicatedarguments.execute_file(fname,arg0,arg1,...)Executethepieceofcodeinthefilewiththeindicatedarguments.

Sometimesyouwanttostoreascriptindexinavariableandexecuteit.Forthisyoucanusethefollowingfunction

script_execute(scr,arg0,arg1,...)Executethescriptwithindexscrwiththegivenarguments.

Timelines

Thefollowingroutinesareavailableforcreatingandchangingtimelines.Don'tchangetimelinesthatareinuse!

timeline_add()Addsanewtimeline.Itreturnstheindexofthetimeline.timeline_delete(ind)Deletesthetimelinewiththegivenindex.Makesurenoinstancesusesthetimelineinanyroom.timeline_clear(ind)Clearsthetimelinewiththegivenindexremovingallitsmoments.Makesurenoinstancesusesthetimelineatthemoment.timeline_moment_add(ind,step,codestr)Addsacodeactiontothetimelineatmomentstep.codestrcontainsthecodefortheactions.Ifthestepdoesnotexistitiscreated.Soyoucanaddmultiplecodeactionsforthesamemoment.timeline_moment_clear(ind,step)Youcanusethisfunctiontoclearalltheactionsforaparticularmoment.

Objects

Alsoobjectscanbemanipulatedandcreatedduringthegameplay.NEVERchangeordeleteanobjectforwhichthereareinstances.Thiscanleadtounexpectedeffectsascertainobjectpropertiesarestoredwiththeinstanceand,hence,changingthemintheobjectwillnothavethedesiredeffect.

object_set_sprite(ind,spr)Setsthespriteoftheobjectwiththegivenindex.Use-1toremovethecurrentspritefromtheobject.object_set_solid(ind,solid)Setswhetherinstancescreatedoftheobjectmustdefaultbesolid(trueorfalse).object_set_visible(ind,vis)Setswhetherinstancescreatedoftheobjectmustdefaultbevisible(trueorfalse).object_set_depth(ind,depth)Setsthedefaultdepthofinstancescreatedoftheobject.object_set_persistent(ind,pers)Setswhetherinstancescreatedoftheobjectmustdefaultbepersistent(trueorfalse).object_set_mask(ind,spr)Setsthespritemaskoftheobjectwiththegivenindex.Use-1tosetthemasktobethespriteoftheobject.object_set_parent(ind,obj)Setstheparentoftheobject.Use-1tonothaveaparent.Changingtheparentchangesthebehaviorofinstancesoftheobject.

Thefollowingroutinesareusefulforcreatingobjectsonthefly.Aswithallresourcechangingroutines,beverycarefulthatyoudon'tcreatenewobjectsallthetime.

object_add()Addsanewobject.Itreturnstheindexoftheobject.Youcannowusethisindexintheroutinesabovetosetcertainpropertiesoftheobjectandthenyoucanusetheindextocreateinstancesoftheobject.object_delete(ind)Deletestheobjectwiththegivenindex.Makesurenoinstancesoftheobjectexistinanyoftherooms.object_event_add(ind,evtype,evnumb,codestr)Togivetheobjectabehaviorwemustdefineeventsfortheobject.Youcanonlyadd

codeactionstoevents.Youneedtospecifytheobject,theeventtype,theeventnumber(usetheconstantsthathavebeenspecifiedbeforefortheevent_perform()function).Finallyyouprovidethecodestringthatmustbeexecuted.Youcanaddmultiplecodeactionstoeachevent.object_event_clear(ind,evtype,evnumb)Youcanusethisfunctiontoclearalltheactionsforaparticularevent.

Creatingobjectsisinparticularusefulwhenyouaredesigningscriptsoractionlibraries.Forexample,aninitializationscriptcancreateanobjecttodisplayatextandanotherscriptcanaddsuchanobjectwithaparticulartext.Inthiswayyouhaveasimplemechanismtodisplaytextswithouttheneedtocreateobjectsusingthestandardinterface.

Rooms

Manipulatingroomsontheflyisadangerousthingtodo.Youhavetorealizethatroomschangeallthetimeduetowhatishappeninginthegame.Thisnormallyonlyinvolvesthecurrentlyactiveroomandtherearemanyroutinesdescribedinprevioussectionstomanipulatetheinstances,backgrounds,andtilesintheactiveroom.Butchangesintheactiveroomwilllastiftheroomispersistent.Hence,youshouldnevermanipulateaspectsofthecurrentlyactiveroomoranyroomthatispersistentandthathasalreadybeenvisitedbefore.Suchchangesingeneralwon'tbenoticedbutmightsometimesevenleadtounexpectederrors.Duetothefactthatroomsarelinkedinacomplicatedwaythereisalsonoroutinetodeletearoom.

Thefollowingroutinesareavailable

room_set_width(ind,w)Setsthewidthfortheroomwiththeindicatedindex.room_set_height(ind,h)Setstheheightfortheroomwiththeindicatedindex.room_set_caption(ind,str)Setsthecaptionfortheroomwiththeindicatedindex.room_set_persistent(ind,val)Setswhethertheroomwiththeindicatedindexispersistentornot.room_set_code(ind,str)Setstheinitializationcodestringfortheroomwiththeindicatedindex.room_set_background_color(ind,col,show)Setsthecolorpropertiesfortheroomwiththeindicatedindexifisdoesnothaveabackgroundimage.colindicatesthecolorandshowindicateswhetherthecolormustbeshownornot.room_set_background(ind,bind,vis,fore,back,x,y,htiled,vtiled,hspeed,vspeed,alpha)

Setsbackgroundwithindexbind(0-7)fortheroomwiththeindicatedindex.visindicateswhetherthebackgroundisvisibleandforewhetheritisactuallyaforeground.backistheindexofthebackgroundimage.x,yindicatethepositionoftheimageandhtiledandvtiledindicatewhethertheimagemustbetiled.hspeedand

vspeedindicatethespeedwithwhichthebackgroundmovesandalphaindicatesanalphatranslucencyvalue(1=solidandfastest).room_set_view(ind,vind,vis,xview,yview,wview,hview,xport,yport,wport,hport,hborder,vborder,hspeed,vspeed,obj)

Setstheviewwithindexvind(0-7)fortheroomwiththeindicatedindex.visindicateswhethertheviewisvisible.xview,yview,wview,andhviewindicatethepositionoftheviewintheroom.xport,yport,wport,andhportindicatethepositiononthescreen.Whentheviewmustfollowanobjecthborderandvborderindicatetheminimalvisibleborderthatmustbekeptaroundtheobject.hspeedandvspeedindicatethemaximalspeedwithwhichtheviewcanmove.objistheindexoftheobjectortheindexoftheinstance.room_set_view_enabled(ind,val)Setswhetherviewsmustbeenabledfortheroomwiththeindicatedindex.room_add()Addsanewroom.Itreturnstheindexoftheroom.Notethattheroomwillnotbepartoftheroomorder.Sothenewroomdoesnothaveapreviousoranextroom.Ifyouwanttomovetoanaddedroomyoumustprovidetheindexoftheroom.room_duplicate(ind)Addsacopyoftheroomwiththegivenindex.Itreturnstheindexoftheroom.room_assign(ind,room)Assignstheindicatedroomtoroomind.Sothismakesacopyoftheroom.room_instance_add(ind,x,y,obj)Addsanewinstanceofobjectobjtotheroom,placingitattheindicateposition.Itreturnstheindexoftheinstance.room_instance_clear(ind)Removesallinstancesfromtheindicatedroom.room_tile_add(ind,back,left,top,width,height,x,y,depth)Addsanewtiletotheroomattheindicateposition.Itreturnstheindexofthetile.backisthebackgroundfromwhichthetileistaken.left,top,widthandheightindicatethepartofthebackgroundthatformsthetile.x,yisthepositionofthetileintheroomanddepthisthedepthofthetile.room_tile_add_ext(ind,back,left,top,width,height,x,y,depth,xscale,yscale,alpha)

Sameasthepreviousroutinebutthistimeyoucanalsospecifyascalingfactorinxandydirectionandanalphatransparencyforthetile.room_tile_clear(ind)Removesalltilesfromtheindicatedroom.

Files,registry,andexecutingprograms

Inmoreadvancedgamesyouprobablywanttoreaddatafromafilethatyouprovidewiththegame.Oryoumightwanttostoreinformationbetweenrunsofthegame.Andinsomesituationsyoumightneedtoexecuteexternalprograms.

Informationcanbefoundinthefollowingpages:

FilesRegistryINIFilesExecutingPrograms

Files

Itisusefultouseexternalfilesingames.Forexample,youcouldmakeafilethatdescribesatwhatmomentscertainthingsshouldhappen.Alsoyouprobablywanttosaveinformationforthenexttimethegameisrun(forexample,thecurrentroom).Thefollowingfunctionsexisttoreadandwritedataintextfiles:

file_text_open_read(fname)Opensthefilewiththeindicatednameforreading.Thefunctionreturnstheidofthefilethatmustbeusedintheotherfunctions.Youcanopenmultiplefilesatthesametime(32max).Don'tforgettoclosethemonceyouarefinishedwiththem.file_text_open_write(fname)Openstheindicatedfileforwriting,creatingitifitdoesnotexist.Thefunctionreturnstheidofthefilethatmustbeusedintheotherfunctions.file_text_open_append(fname)Openstheindicatedfileforappendingdataattheend,creatingitifitdoesnotexist.Thefunctionreturnstheidofthefilethatmustbeusedintheotherfunctions.file_text_close(fileid)Closesthefilewiththegivenfileid.file_text_write_string(fileid,str)Writesthestringtothefilewiththegivenfileid.file_text_write_real(fileid,x)Writetherealvaluetothefilewiththegivenfileid.(Asseparatorbetweentheintegeranddecimalpartalwaysadotisused.file_text_writeln(fileid)Writeanewlinecharactertothefile.file_text_read_string(fileid)Readsastringfromthefilewiththegivenfileidandreturnsthisstring.Astringendsattheendofline.file_text_read_real(fileid)Readsarealvaluefromthefileandreturnsthisvalue.file_text_readln(fileid)Skipstherestofthelineinthefileandstartsatthestartofthenextline.file_text_eof(fileid)Returnswhetherwereachedtheendofthefile.file_text_eoln(fileid)Returnswhetherwereachedtheendofa

lineinthefile.

Tomanipulatefilesinthefilesystemyoucanusethefollowingfunctions:

file_exists(fname)Returnswhetherthefilewiththegivennameexists(true)ornot(false).file_delete(fname)Deletesthefilewiththegivenname.file_rename(oldname,newname)Renamesthefilewithnameoldnameintonewname.file_copy(fname,newname)Copiesthefilefnametothenewname.directory_exists(dname)Returnswhethertheindicateddirectorydoesexist.Thenamemustincludethefullpath,notarelativepath.directory_create(dname)Createsadirectorywiththegivenname(includingthepathtowardsit)ifitdoesnotexist.Thenamemustincludethefullpath,notarelativepath.file_find_first(mask,attr)Returnsthenameofthefirstfilethatsatisfiesthemaskandtheattributes.Ifnosuchfileexists,theemptystringisreturned.Themaskcancontainapathandcancontainwildchars,forexample'C:\temp\*.doc'.Theattributesgivetheadditionalfilesyouwanttosee.(Sothenormalfilesarealwaysreturnedwhentheysatisfythemask.)Youcanaddupthefollowingconstantstoseethetypeoffilesyouwant:

fa_readonlyread-onlyfiles

fa_hiddenhiddenfiles

fa_sysfilesystemfiles

fa_volumeidvolume-idfiles

fa_directorydirectories

fa_archivearchivedfiles

file_find_next()Returnsthenameofthenextfilethatsatisfiesthepreviouslygivenmaskandtheattributes.Ifnosuchfileexists,theemptystringisreturned.file_find_close()Mustbecalledafterhandlingallfilestofreememory.file_attributes(fname,attr)Returnswhetherthefilehasalltheattributesgiveninattr.Useacombinationoftheconstantsindicatedabove.

Thefollowingfunctionscanbeusedtochangefilenames.Notethatthesefunctionsdonotworkontheactualfilestheyonlydealwiththestrings.

filename_name(fname)Returnsthenamepartoftheindicatedfilename,withtheextensionbutwithoutthepath.filename_path(fname)Returnsthepathpartoftheindicatedfilename,includingthefinalbackslash.filename_dir(fname)Returnsthedirectorypartoftheindicatedfilename,whichnormallyisthesameasthepathexceptforthefinalbackslash.filename_drive(fname)Returnsthedriveinformationofthefilename.filename_ext(fname)Returnstheextensionpartoftheindicatedfilename,includingtheleadingdot.filename_change_ext(fname,newext)Returnstheindicatedfilename,withtheextension(includingthedot)changedtothenewextension.Byusinganemptystringasthenewextensionyoucanremovetheextension.

Inraresituationsyoumightneedtoreaddatafrombinaryfiles.Thefollowinglow-levelroutinesexistforthis:

file_bin_open(fname,mod)Opensthefilewiththeindicatedname.Themodeindicateswhatcanbedonewiththefile:0=reading,1=writing,2=bothreadingandwriting).Whenthefiledoesnotexistitiscreated.Thefunctionreturnstheidofthefilethatmustbeusedintheotherfunctions.Youcanopenmultiplefilesatthesametime(32max).Don'tforgettoclosethemonceyouarefinishedwiththem.file_bin_rewrite(fileid)Rewritesthefilewiththegivenfileid,thatis,clearsitandstartswritingatthestart.file_bin_close(fileid)Closesthefilewiththegivenfileid.file_bin_size(fileid)Returnsthesize(inbytes)ofthefilewiththegivenfileid.file_bin_position(fileid)Returnsthecurrentposition(inbytes;0isthefirstposition)ofthefilewiththegivenfileid.file_bin_seek(fileid,pos)Movesthecurrentpositionofthefiletotheindicatedposition.Toappendtoafilemovethepositiontothesizeofthefilebeforewriting.

file_bin_write_byte(fileid,byte)Writesabyteofdatatothefilewiththegivenfileid.file_bin_read_byte(fileid)Readsabyteofdatafromthefileandreturnsthis.

Iftheplayerhascheckedsecuremodeinhispreferences,foranumberoftheseroutines,youarenotallowedtospecifyapath,andonlyfilesintheapplicationfoldercane.g.bewritten.

Ifyouincludedfilesinthegameexecutableanddidnotautomaticallyexportthematthestartofthegame,youcanusethefollowingfunctionstodothis.

export_include_file(fname)Exportstheincludedfilewiththenamefname.Thismustbeastringvariable,sodon'tforgetthequotes.export_include_file_location(fname,location)Exportstheincludedfilewiththenamefnametothegivenlocation.Locationmustcontainthepathandthefilename.discard_include_file(fname)Discardtheincludedfilewiththenamefname,freeingthememoryused.Thismustbeastringvariable,sodon'tforgetthequotes.

Thefollowingfourread-onlyvariablescanbeuseful:

game_id*Uniqueidentifierforthegame.Youcanusethisifyouneedauniquefilename.working_directory*Workingdirectoryforthegame.(Notincludingthefinalbackslash.)program_directory*Directoryinwhichthegameexecutableisstored.(Notincludingthefinalbackslash.)Whenyourunastandalonegamethisisnormallythesameastheworkingdirectoryunlessthegamee.g.opensafileusingthefileselector.Notethatwhentestingagameyouarecreatingtheprogramandworkingdirectorywillbedifferent.Inthatcasetheworkingdirectoryistheplacewheretheeditableversionisstoredwhiletheprogramdirectoryisatemporarydirectoryfortesting.temp_directory*Temporarydirectorycreatedforthegame.(Notincludingthefinalbackslash.)Youcanstoretemporaryfileshere.

Theywillberemovedattheendofthegame.

Incertainsituationsyoumightwanttogiveplayersthepossibilityofprovidingcommandlineargumentstothegametheyarerunning(forexampletocreatecheatsorspecialmodes).Togettheseargumentsyoucanusethefollowingtworoutines.

parameter_count()Returnsthenumberofcommand-lineparameters.Theactualparameterscanberetrievedwiththefollowingfunction.parameter_string(n)Returnscommand-lineparametersn.Thefirstparameterhasindex1.Thelastonehasindexparameter_count().Index0isaspecialone.Itisthefilenameofthegameexecutable(includingthepath).

Youcanreadthevalueofenvironmentvariablesusingthefollowingfunction:

environment_get_variable(name)Returnsthevalue(astring)oftheenvironmentvariablewiththegivenname.

Finally,ifyouareinterestedinthesizeofthediskandthefreespace,youcanusethefollowingfunctions:

disk_size(drive)Returnsthesizeoftheindicateddriveinbytes.drivemustbeacapitalletter,e.g.'C'.Ifyoudonotprovidethedrive,thedriveofthecurrentworkingdirectoryisused.disk_free(drive)Returnstheamountoffreespaceontheindicateddriveinbytes.drivemustbeacapitalletter,e.g.'C'.Ifyoudonotprovidethedrive,thedriveofthecurrentworkingdirectoryisused.

Registry

Ifyouwanttostoreasmallamountofinformationbetweenrunsofthegamethereisasimplermechanismthanusingafile.Youcanusetheregistry.TheregistryisalargedatabasethatWindowsmaintainstokeeptrackofallsortsofsettingsforprograms.Anentryhasaname,andavalue.Youcanusebothstringandrealvalues.Thefollowingfunctionsexist:

registry_write_string(name,str)Createsanentryintheregistrywiththegivennameandstringvalue.registry_write_real(name,x)Createsanentryintheregistrywiththegivennameandrealvalue.registry_read_string(name)Returnsthestringthatthegivennameholds.(Thenamemustexist.Otherwiseanemptystringisreturned.)registry_read_real(name)Returnstherealvaluethatthegivennameholds.(Thenamemustexist.Otherwisethenumber0isreturned.)registry_exists(name)Returnswhetherthegivennameexists.

Actually,valuesintheregistryaregroupedintokeys.Theaboveroutinesallworkonvalueswithinthekeythatisespeciallycreatedforyourgame.Yourprogramcanusethistoobtaincertaininformationaboutthesystemthegameisrunningon.Youcanalsoreadvaluesinotherkeys.Youcanwritethemalsobutbeverycareful.YOUCANEASILYDESTROYYOURSYSTEMthisway.(Writeisnotallowedinsecuremode.)Notethatkeysareagainplacedingroups.ThefollowingroutinesdefaultworkonthegroupHKEY_CURRENT_USER.Butyoucanchangetherootgroup.So,forexample,ifyouwanttofindoutthecurrenttempdir,use

path=registry_read_string_ext('\Environment','TEMP');

Thefollowingfunctionsexist:

registry_write_string_ext(key,name,str)Createsanentryinthekeyintheregistrywiththegivennameandstringvalue.

registry_write_real_ext(key,name,x)Createsanentryinthekeyintheregistrywiththegivennameandrealvalue.registry_read_string_ext(key,name)Returnsthestringthatthegivennameintheindicatedkeyholds.(Thenamemustexist.Otherwiseanemptystringisreturned.)registry_read_real_ext(key,name)Returnstherealvaluethatthegivennameintheindicatedkeyholds.(Thenamemustexist.Otherwisethenumber0isreturned.)registry_exists_ext(key,name)Returnswhetherthegivennameexistsinthegivenkey.registry_set_root(root)Setstherootfortheotherroutines.Usethefollowingvalues:

0=HKEY_CURRENT_USER1=HKEY_LOCAL_MACHINE2=HKEY_CLASSES_ROOT3=HKEY_USERS

INIfiles

TopasscertainparametersettingstoprogramsastandardmechanismistheuseofINIfiles.INIfilescontainsectionsandeachsectioncontainsanumberofname-valuepairs.Forexample,hereisatypicalINIfile:

[Form]

Top=100

Left=100

Caption=Thebestgameever

[Game]

MaxScore=12324

Thisfilecontainstwosections,onecallFormandtheothercalledGame.Thefirstsectioncontainsthreepairs.Thefirsttwohavearealvaluewhilethethirdhasastringvalue.SuchINIfilesareeasytocreateandchange.ThefollowingfunctionsexistinGameMakertoreadandchangethedatainthem.

ini_open(name)OpenstheINIfilewiththegivenname.Theinifilemustbestoredinthesamefolderasthegame!ini_close()ClosesthecurrentlyopenINIfile.ini_read_string(section,key,default)Readsthestringvalueoftheindicatedkeyintheindicatedsection.Whenthekeyorsectiondoesnotexistthedefaultvalueisreturned.ini_read_real(section,key,default)Readstherealvalueoftheindicatedkeyintheindicatedsection.Whenthekeyorsectiondoesnotexistthedefaultvalueisreturned.ini_write_string(section,key,value)Writesthestringvaluefortheindicatedkeyintheindicatedsection.ini_write_real(section,key,value)Writestherealvaluefortheindicatedkeyintheindicatedsection.ini_key_exists(section,key)Returnswhethertheindicatedkeyexistsintheindicatedsection.ini_section_exists(section)Returnswhethertheindicatedsectionexists.

ini_key_delete(section,key)Deletestheindicatedkeyfromtheindicatedsection.ini_section_delete(section)Deletestheindicatedsection.

Executingprograms

GameMakeralsohasthepossibilitytostartexternalprograms.Therearetwofunctionsavailableforthis:execute_programandexecute_shell.Thefunctionexecute_programstartsaprogram,possiblywithsomearguments.Itcanwaitfortheprogramtofinish(pausingthegame)orcontinuethegame.Thefunctionexecute_shellopensafile.Thiscanbeanyfileforwhichsomeassociationisdefined,e.g.anhtml-file,awordfile,etc.Oritcanbeaprogram.Itcannotwaitforcompletionsothegamewillcontinue.

execute_program(prog,arg,wait)Executesprogramprogwithargumentsarg.waitindicateswhethertowaitforfinishing.execute_shell(prog,arg)Executestheprogram(orfile)intheshell.

Bothfunctionswillnotworkiftheplayersetsthesecuremodeinthepreferences.Youcancheckthisusingtheread-onlyvariable:

secure_mode*Whetherthegameisrunninginsecuremode.

Datastructures


Ingamesyouoftenneedtostoreinformation.Forexampleyouneedtostorelistsofitemsthatapersoncarriesoryouwanttostoreplacesthatstillneedtobevisited.Youcanusethearraysforthis.Butifyouwanttodomorecomplicatedoperations,likesortingthedataorsearchingforaparticularitem,youneedtowritelargepiecesofGMLcodewhichcanbeslowtoexecute.

Toremedythis,GameMakerhasanumberofbuilt-indatastructuresthatcanbeaccessedthroughfunctions.Atthemomenttherearesixdifferenttypesofdatastructureavailable:stacks,queues,lists,maps,priorityqueues,andgrids.Eachofthesedatastructuresistunedforaparticulartypeofuse(seebelow).

Alldatastructuresworkgloballyinthesameway.Youcancreateadatastructurewithafunctionthatreturnsanidforthestructures.Youusethisidtoperformoperationsonthedatastructures.Onceyouaredoneyoudestroythedatastructureagaintosavestorage.Youcanuseasmanyofthestructuresatthesamemomentasyouwant.Allstructurecanstorebothstringsandrealvalues.

Pleasenotethatdatastructuresandtheircontentarenotsavedwhenyousavethegameusingtheactionsorfunctionsforthat.Ifyouusedatastructuresandwanttoallowforsavesyouhavetocreateyourownmechanismforthat.

Whencomparingvalues,forexamplewhensearchinginamaporsortingalist,GameMakermustdecidewhentwovaluesareequal.Forstringsandintegervaluesthisisclearbutforrealnumbers,duetoround-offerrors,equalnumbercaneasilybecomeunequal.Forexample(5/3)*3willnotbeequalto5.Toavoidthis,aprecisionisused.Whenthedifferencebetweentwonumbersissmallerthanthisprecisiontheyareconsideredequal.Defaultaprecisionof0.0000001isused.Youcan

changethisprecisionusingthefollowingfunction:

ds_set_precision(prec)Setstheprecisionusedforcomparisons.

ThisprecisionisusedinalldatastructuresbutnotinothercomparisonsinGML!

Informationondatastructurescanbefoundinthefollowingpages:

StacksQueuesListsMapsPriorityQueuesGrids

Stacks

AstackdatastructureisasocalledLIFO(Last-InFirst-Out)structures.Youcanpushvaluesonastackandtheremovethemagainbypoppingthemfromthestack.Thevaluethatwaspushedonthestackmostrecentlyisthefirsttobepoppedfromitagain.Stacksareoftenusedwhenthereareinterruptstohandle,orwhenhavingrecursivefunctions.Thefollowingfunctionsexistforstacks:

ds_stack_create()Createsanewstack.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticularstack.Youcancreatemultiplestacks.ds_stack_destroy(id)Destroysthestackwiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_stack_clear(id)Clearsthestackwiththegivenid,removingalldatafromitbutnotdestroyingit.ds_stack_copy(id,source)Copiesthestacksourceintothestackwiththegivenid.ds_stack_size(id)Returnsthenumberofvaluesstoredinthestack.ds_stack_empty(id)Returnswhetherthestackisempty.Thisisthesameastestingwhetherthesizeis0.ds_stack_push(id,val)Pushesthevalueonthestack.ds_stack_pop(id)Returnsthevalueonthetopofthestackandremovesitfromthestack.ds_stack_top(id)Returnsthevalueonthetopofthestackbutdoesnotremoveitfromthestack.ds_stack_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.Thisprovidesaneasymechanismforsavingdatastructures.ds_stack_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Queues

AqueueissomewhatsimilartoastackbutitworksonaFIFO(First-InFirst-Out)basis.Thevaluethatisputinthequeuefirstisalsothefirsttoberemovedfromit.Itworkslikeaqueueinashop.Thepersonwhoisfirstinaqueueisservedfirst.Queuesaretypicallyusedtostorethingsthatstillneedtobedonebuttherearemanyotheruses.Thefollowingfunctionsexist(notethatthefirstfiveareequivalenttothefunctionsforstacks;alldatastructureshavethesefivefunctions):

ds_queue_create()Createsanewqueue.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticularqueue.Youcancreatemultiplequeues.ds_queue_destroy(id)Destroysthequeuewiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_queue_clear(id)Clearsthequeuewiththegivenid,removingalldatafromitbutnotdestroyingit.ds_queue_copy(id,source)Copiesthequeuesourceintothequeuewiththegivenid.ds_queue_size(id)Returnsthenumberofvaluesstoredinthequeue.ds_queue_empty(id)Returnswhetherthequeueisempty.Thisisthesameastestingwhetherthesizeis0.ds_queue_enqueue(id,val)Entersthevalueinthequeue.ds_queue_dequeue(id)Returnsthevaluethatislongestinthequeueandremovesitfromthequeue.ds_queue_head(id)Returnsthevalueattheheadofthequeue,thatis,thevaluethathasbeenthelongestinthequeue.(Itdoesnotremoveitfromthequeue.)ds_queue_tail(id)Returnsthevalueatthetailofthequeue,thatis,thevaluethathasmostrecentlybeenaddedtothequeue.(Itdoesnotremoveitfromthequeue.)ds_queue_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.This

providesaneasymechanismforsavingdatastructures.ds_queue_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Lists

Aliststoresacollectionofvaluesinaparticularorder.Youcanaddvaluesattheendorinsertthemsomewhereinthemiddleofthelist.Youcanaddressthevaluesusinganindex.Alsoyoucansorttheelements,eitherinascendingordescendingorder.Listscanbeusedinmanyways,forexampletostorechangingcollectionsofvalues.Theyareimplementedusingsimplearraysbut,asthisisdoneincompiledcodeitisalotfasterthanusinganarrayyourself.Thefollowingfunctionsareavailable:

ds_list_create()Createsanewlist.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticularlist.ds_list_destroy(id)Destroysthelistwiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_list_clear(id)Clearsthelistwiththegivenid,removingalldatafromitbutnotdestroyingit.ds_list_copy(id,source)Copiesthelistsourceintothelistwiththegivenid.ds_list_size(id)Returnsthenumberofvaluesstoredinthelist.ds_list_empty(id)Returnswhetherthelistisempty.Thisisthesameastestingwhetherthesizeis0.ds_list_add(id,val)Addsthevalueattheendofthelist.ds_list_insert(id,pos,val)Insertsthevalueatpositionposinthelist.Thefirstpositionis0,thelastpositionisthesizeofthelistminus1.ds_list_replace(id,pos,val)Replacesthevalueatpositionposinthelistwiththenewvalue.ds_list_delete(id,pos)Deletesthevalueatpositionposinthelist.(Position0isthefirstelement.)ds_list_find_index(id,val)Findthepositionstoringtheindicatedvalue.Ifthevalueisnotinthelist-1isreturned.ds_list_find_value(id,pos)Returnsthevaluestoredatthe

indicatedpositioninthelist.ds_list_sort(id,ascend)Sortsthevaluesinthelist.Whenascendistruethevaluesaresortedinascendingorder,otherwiseindescendingorder.ds_list_shuffle(id)Shufflesthevaluesinthelistsuchthattheyendupinarandomorder.ds_list_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.Thisprovidesaneasymechanismforsavingdatastructures.ds_list_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Maps

Inquiteafewsituationsyouneedtostorepairsconsistingofakeyandavalue.Forexample,acharactercanhaveanumberofdifferentitemsandforeachitemithasaparticularnumberofthose.Inthiscasetheitemisthekeyandthenumberisthevalue.Mapsmaintainsuchpairs,sortedbykey.Youcanaddpairstothemapandsearchforthevaluecorrespondingtocertainkeys.Becausethekeysaresortedyoucanalsofindpreviousandnextkeys.Sometimesitisalsousefultouseamaptojuststorekeyswithoutacorrespondingvalue.Inthatcaseyoucansimplyuseavalueof0.Thefollowingfunctionsexist:

ds_map_create()Createsanewmap.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticularmap.ds_map_destroy(id)Destroysthemapwiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_map_clear(id)Clearsthemapwiththegivenid,removingalldatafromitbutnotdestroyingit.ds_map_copy(id,source)Copiesthemapsourceintothemapwiththegivenid.ds_map_size(id)Returnsthenumberofkey-valuepairsstoredinthemap.ds_map_empty(id)Returnswhetherthemapisempty.Thisisthesameastestingwhetherthesizeis0.ds_map_add(id,key,val)Addsthekey-valuepairtothemap.ds_map_replace(id,key,val)Replacesthevaluecorrespondingwiththekeywithanewvalue.ds_map_delete(id,key)Deletesthekeyandthecorrespondingvaluefromthemap.(Iftherearemultipleentrieswiththesamekey,onlyoneisremoved.)ds_map_exists(id,key)Returnswhetherthekeyexistsinthemap.ds_map_find_value(id,key)Returnsthevaluecorrespondingtothekey.

ds_map_find_previous(id,key)Returnsthelargestkeyinthemapsmallerthantheindicatedkey.(Notethatthekeyisreturned,notthevalue.Youcanusethepreviousroutinetofindthevalue.)ds_map_find_next(id,key)Returnsthesmallestkeyinthemaplargerthantheindicatedkey.ds_map_find_first(id)Returnsthesmallestkeyinthemap.ds_map_find_last(id)Returnsthelargestkeyinthemap.ds_map_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.Thisprovidesaneasymechanismforsavingdatastructures.ds_map_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Priorityqueues

Inapriorityqueueanumberofvaluesarestored,eachwithapriority.Youcanquicklyfindthevalueswithminimumandmaximumpriority.Usingthisdatastructureyoucanhandlecertainthingsintheorderofpriority.Thefollowingfunctionsexist:

ds_priority_create()Createsanewpriorityqueue.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticularpriorityqueue.ds_priority_destroy(id)Destroysthepriorityqueuewiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_priority_clear(id)Clearsthepriorityqueuewiththegivenid,removingalldatafromitbutnotdestroyingit.ds_priority_copy(id,source)Copiesthepriorityqueuesourceintothepriorityqueuewiththegivenid.ds_priority_size(id)Returnsthenumberofvaluesstoredinthepriorityqueue.ds_priority_empty(id)Returnswhetherthepriorityqueueisempty.Thisisthesameastestingwhetherthesizeis0.ds_priority_add(id,val,prio)Addsthevaluewiththegivenprioritytothepriorityqueue.ds_priority_change_priority(id,val,prio)Changesthepriorityofthegivenvalueinthepriorityqueue.ds_priority_find_priority(id,val)Returnsthepriorityofthegivenvalueinthepriorityqueue.ds_priority_delete_value(id,val)Deletesthegivenvalue(withitspriority)fromthepriorityqueue.ds_priority_delete_min(id)Returnsthevaluewiththesmallestpriorityanddeletesitfromthepriorityqueue.ds_priority_find_min(id)Returnsthevaluewiththesmallestprioritybutdoesnotdeleteitfromthepriorityqueue.ds_priority_delete_max(id)Returnsthevaluewiththelargestpriorityanddeletesitfromthepriorityqueue.

ds_priority_find_max(id)Returnsthevaluewiththelargestprioritybutdoesnotdeleteitfromthepriorityqueue.ds_priority_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.Thisprovidesaneasymechanismforsavingdatastructures.ds_priority_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Grids

Agridissimplyatwo-dimensionalarray.Agridhasanintegerwidthandheight.Thestructureallowsyoutosetandretrievethevalueofcellsinthegridbygivingtheindexofit(whichstartswith0inboththex-andthey-direction).Butyoucanalsosetthevalueinregions,addvalues,andretrievethesum,max,min,andmeanvalueoveraregion.Thestructureisusefultorepresente.g.aplayingfield.Eventhoughallfunctionalitycanalsobeachievedusingtwo-dimensionalarrays,theoperationsonregionsarealotfaster.Thefollowingfunctionsexist:

ds_grid_create(w,h)Createsanewgridwiththeindicatedwidthandheight.Thefunctionreturnsanintegerasanidthatmustbeusedinallotherfunctionstoaccesstheparticulargrid.ds_grid_destroy(id)Destroysthegridwiththegivenid,freeingthememoryused.Don'tforgettocallthisfunctionwhenyouarereadywiththestructure.ds_grid_copy(id,source)Copiesthegridsourceintothegridwiththegivenid.ds_grid_resize(id,w,h)Resizesthegridtothenewwidthandheight.Existingcellskeeptheiroriginalvalue.ds_grid_width(id)Returnsthewidthofthegridwiththeindicatedid.ds_grid_height(id)Returnstheheightofthegridwiththeindicatedid.ds_grid_clear(id,val)Clearsthegridwiththegivenid,totheindicatedvalue(canbothbeanumberorastring).ds_grid_set(id,x,y,val)Setstheindicatedcellinthegridwiththegivenid,totheindicatedvalue(canbothbeanumberorastring).ds_grid_add(id,x,y,val)Addthevaluetotheindicatedcellinthegridwiththegivenid.Forstringsthiscorrespondstoconcatenation.ds_grid_multiply(id,x,y,val)Multipliesthevaluetotheindicatedcellinthegridwiththegivenid.Isonlyvalidfornumbers.ds_grid_set_region(id,x1,y1,x2,y2,val)Setstheallcellsintheregioninthegridwiththegivenid,totheindicatedvalue(canbothbeanumberorastring).

ds_grid_add_region(id,x1,y1,x2,y2,val)Addthevaluetothecellintheregioninthegridwiththegivenid.Forstringsthiscorrespondstoconcatenation.ds_grid_multiply_region(id,x1,y1,x2,y2,val)Multipliesthevaluetothecellsintheregioninthegridwiththegivenid.Isonlyvalidfornumbers.ds_grid_set_disk(id,xm,ym,r,val)Setsallcellsinthediskwithcenter(xm,ym)andradiusr.ds_grid_add_disk(id,xm,ym,r,val)Addthevaluetoallcellsinthediskwithcenter(xm,ym)andradiusr.ds_grid_multiply_disk(id,xm,ym,r,val)Multiplythevaluetoallcellsinthediskwithcenter(xm,ym)andradiusr.ds_grid_set_grid_region(id,source,x1,y1,x2,y2,xpos,ypos)Copiesthecontentsofthecellsintheregioningridsourcetogridid.xposandyposindicatetheplacewheretheregionmustbeplacedinthegrid.(Canalsobeusedtocopyvaluesfromoneplaceinagridtoanother.)ds_grid_add_grid_region(id,source,x1,y1,x2,y2,xpos,ypos)Addsthecontentsofthecellsintheregioningridsourcetogridid.xposandyposindicatetheplacewheretheregionmustbeaddedinthegrid.(idandsourcecanbethesame.)ds_grid_multiply_grid_region(id,source,x1,y1,x2,y2,xpos,ypos)

Multipliesthecontentsofthecellsintheregioningridsourcetogridid.xposandyposindicatetheplacewheretheregionmustbemultipliedinthegrid.(idandsourcecanbethesame.)Onlyvalidfornumbers.ds_grid_get(id,x,y)Returnsthevalueoftheindicatedcellinthegridwiththegivenid.ds_grid_get_sum(id,x1,y1,x2,y2)Returnsthesumofthevaluesofthecellsintheregioninthegridwiththegivenid.Doesonlyworkwhenthecellscontainnumbers.ds_grid_get_max(id,x1,y1,x2,y2)Returnsthemaximumofthevaluesofthecellsintheregioninthegridwiththegivenid.Doesonlyworkwhenthecellscontainnumbers.ds_grid_get_min(id,x1,y1,x2,y2)Returnstheminimumofthevaluesofthecellsintheregioninthegridwiththegivenid.Doesonlyworkwhenthecellscontainnumbers.

ds_grid_get_mean(id,x1,y1,x2,y2)Returnsthemeanofthevaluesofthecellsintheregioninthegridwiththegivenid.Doesonlyworkwhenthecellscontainnumbers.ds_grid_get_disk_sum(id,xm,ym,r)Returnsthesumofthevaluesofthecellsinthedisk.ds_grid_get_disk_min(id,xm,ym,r)Returnstheminofthevaluesofthecellsinthedisk.ds_grid_get_disk_max(id,xm,ym,r)Returnsthemaxofthevaluesofthecellsinthedisk.ds_grid_get_disk_mean(id,xm,ym,r)Returnsthemeanofthevaluesofthecellsinthedisk.ds_grid_value_exists(id,x1,y1,x2,y2,val)Returnswhetherthevalueappearssomewhereintheregion.ds_grid_value_x(id,x1,y1,x2,y2,val)Returnsthex-coordinateofthecellinwhichthevalueappearsintheregion.ds_grid_value_y(id,x1,y1,x2,y2,val)Returnsthey-coordinateofthecellinwhichthevalueappearsintheregion.ds_grid_value_disk_exists(id,xm,ym,r,val)Returnswhetherthevalueappearssomewhereinthedisk.ds_grid_value_disk_x(id,xm,ym,r,val)Returnsthex-coordinateofthecellinwhichthevalueappearsinthedisk.ds_grid_value_disk_y(id,xm,ym,r,val)Returnsthey-coordinateofthecellinwhichthevalueappearsinthedisk.ds_grid_shuffle(id)Shufflesthevaluesinthegridsuchthattheyendupinarandomorder.ds_grid_write(id)Turnsthedatastructureintoastringandreturnsthisstring.Thestringcanthenbeusedtoe.g.saveittoafile.Thisprovidesaneasymechanismforsavingdatastructures.ds_grid_read(id,str)Readsthedatastructurefromthegivenstring(ascreatedbythepreviouscall).

Creatingparticles


Particlesystemsaremeanttocreatespecialeffects.Particlesaresmallelements,representedbyalittlesprite.Suchparticlesmovearoundaccordingtopredefinedrulesandcanchangesize,orientation,color,etc.whiletheymove.Manysuchparticlestogethercancreatee.g.fireworks,flames,explosions,rain,snow,starfields,flyingdebris,etc.

GameMakercontainsanextensiveparticlesystemthatcanbeusedtocreategreateffects.Becauseofitsgeneralityitisnotsimpletousesobetterreadthissectioncarefullybeforetrying.

Ifthisistoocomplicatedforyou,thereisalsoaverysimplemechanismtocreatedifferenttypesofexplosions,smoke,rain,andevenfireworks.

Particlesystemshavemanyparametersanditisnotalwayseasytounderstandhowtocreatetheeffectsyouwant.Firstofallthereareparticletypes.Aparticletypedefinesaparticularkindofparticles.Suchtypeshavemanyparametersthatdescribetheshape,size,color,andmotionoftheparticles.Particletypesneedtobedefinedonlyonceandcanthenbeusedeverywhereinthegame.

Secondlythereareparticlesystems.Therecanbedifferentparticlesystemsinthegame.Aparticlesystemcanhaveparticlesofthedifferenttypes.Aparticlesystemhasemittersthatcreatetheparticles,eithercontinuouslyorinbursts.Itcanalsohaveattractorsthatattractparticles.Finally,itcanhavedestroyersthatdestroyparticles.Onceparticlesarecreatedinaparticlesystem,theyareautomaticallyhandled(updatedanddrawn)bythesystem.

Informationonparticlescanbefoundinthefollowingpages:

SimpleEffectsParticleTypesParticleSystems

EmittersAttractorsDestroyersDeflectorsChangersFireworkExample

SimpleEffects

Theeasiestwayofcreatingparticlesistousetheeffectsmechanism.Effectsarecreatedusingtheparticlesystembutyoudonothavetoworryaboutallthedetails.Yousimplyspecifythetypeofeffect,thepositionwhereitmustbecreated,itssize,anditscolor.Thatisall.

Thereareanumberofdifferentkindsofeffects:

ef_explosion

ef_ring

ef_ellipse

ef_firework

ef_smoke

ef_smokeup

ef_star

ef_spark

ef_flare

ef_cloud

ef_rain

ef_snow

Someyouwanttocreatejustonce(liketheexplosion)andsomeyouwanttocreateineverystep(likethesmokeortherain).Notethatrainandsnowarealwayscreatedatthetopoftheroomsothepositionisirrelevantinthiscase.

Eventhoughthismightsoundlimited,theycanactuallybeusedtocreategreateffects.Forexamplebycreatingasmalpuffofredsmokebelowamovingspaceshipineachstep,atailoffireiscreated.Thefollowingtwofunctionsexisttocreatetheeffects:

effect_create_below(kind,x,y,size,color)Createsaneffectofthegivenkind(seeabove)attheindicatedposition.sizegivethesizeasfollows:0=small,1=medium,2=large.colorindicatesthecolortobeused.Theeffectiscreatedbelowtheinstances,thatis,atadepth

of100000.effect_create_above(kind,x,y,size,color)Similartothepreviousfunctionbutthistimetheeffectiscreatedontopoftheinstances,thatis,atadepthof-100000.

Ifyouwanttoremovealleffects,callthefollowingfunction:

effect_clear()Clearsalleffects.

Particletypes

Aparticletypedescribestheshape,color,motion,etc.ofaparticularkindofparticles.Youneedtodefineaparticletypeonlyonceinthegame.Afterthisitcanbeusedinanyparticlesysteminthegame.Particletypeshavealargenumberofparametersthatcanbeusedtochangeallaspectsofit.Settingtheserightyoucancreatealmostanyeffectyoulike.Wewilldiscussthesettingsbelow.

Anumberofroutinesareavailabletocreatenewparticletypesanddestroythemagain:

part_type_create()Createsanewparticletype.Itreturnstheindexofthetype.Thisindexmustbeusedinallcallsbelowtosetthepropertiesoftheparticletype.Soyouwilloftenstoreitinaglobalvariable.part_type_destroy(ind)Destroysparticletypeind.Callthisifyoudon'tneeditanymoretosavespace.part_type_exists(ind)Returnswhethertheindicatedparticletypeexists.part_type_clear(ind)Clearstheparticletypeindtoitsdefaultsettings.

Theshapeofaparticle

Aparticlehasashape.Thisshapeisindicatedbyasprite.Youcanuseanyspriteyoulikeforyourparticlesbutthereare15built-insprites.Theseareall64x64insizeandhavealphavaluessetsuchthattheynicelyblendwiththebackground.Theyareindicatebythefollowingconstants:

pt_shape_pixel

pt_shape_disk

pt_shape_square

pt_shape_line

pt_shape_star

pt_shape_circle

pt_shape_ring

pt_shape_sphere

pt_shape_flare

pt_shape_spark

pt_shape_explosion

pt_shape_cloud

pt_shape_smoke

pt_shape_snow

Yousettheshapeusingthefollowingfunction:

part_type_shape(ind,shape)Setstheshapeoftheparticletypetoanyoftheconstantsabove(defaultispt_shape_pixel).

Youcanalsouseyourownspritefortheparticle.Ifthespritehasmultiplesubimagesyoucanindicatewhatshouldbedonewiththem.Youcanpickarandomone,animatethesprite,startatthebeginningoftheanimationoratarandomplace,etc.Youusethefollowingfunctionforthis.

part_type_sprite(ind,sprite,animat,stretch,random)Setsyourownspritefortheparticletype.Withanimateyouindicatewhetherthespriteshouldbeanimated(1)ornot(0).Withstretch(1or0)youindicatewhethertheanimationmustbestretchedoverthelifetimeoftheparticle.Andwithrandom(1or0)youcanindicatewhetherarandomsubimagemustbechoosenasstartingimage.

Onceyouhavechoosenthespritefortheparticletype(eitheradefaultshapeoryourown)youcanindicatethesizeofit.Asizeof1indicatesthenormalsizeofthesprite.Aparticletypecanbedefinedsuchthatallparticleshavethesamesizeorhavedifferentsizes.Youcanindicatearangeofsizes.Also,youcanindicatewhetherthesizeshouldchangeoverthelifetimeoftheparticleandwhethersomewigglinginthesizewillhappen,givingablinkingeffect.

part_type_size(ind,size_min,size_max,size_incr,size_wiggle)

Setsthesizeparametersfortheparticletype.Youspecifytheminimumstartingsize,themaximumstartingsize,thesizeincreaseineachstep(useanegativenumberforadecreaseinsize)andtheamountofwiggling.(Thedefaultsizeis1anddefaultthesizedoesnotchange.)part_type_scale(ind,xscale,yscale)Setsthehorizontalandverticalscale.Thisfactorismultipliedwiththesize.Itisinparticularusefulwhenyouneedtoscaledifferentlyinx-andy-direction.

Theparticlesalsohaveanorientation.Againtheorientationcanbethesameforallparticles,canbedifferent,andcanchangeoverthelifetimeofthesprite.Theanglesspecifycounter-clockwiserotations,indegrees.

part_type_orientation(ind,ang_min,ang_max,ang_incr,ang_wiggle,ang_relative)

Setstheorientationanglepropertiesfortheparticletype.Youspecifytheminimumangle,themaximumangle,theincreaseineachstepandtheamountofwigglinginangle.(Defaultallvaluesare0.)Youcanalsoindicatewhetherthegivenangleshouldberelative(1)tothecurrentdirectionofmotionorabsolute(0).E.g.bysettingallvaluesto0butang_relativeto1,theparticleorientationwillpreciselyfollowthepathoftheparticle.

Colorandblending

Particleswillhaveacolor.Therearedifferentwaysinwhichyoucanspecifycolorsforaparticle.Thesimplestwayistoindicateasinglecolor.Youcanalsospecifytwoorthreecolorsbetweenwhichthecoloroftheparticleisinterpolatedduringitslifetime.Forexample,theparticlecanstartwhiteandbecomemoreandmoreblackoveritslifetime.Anotherpossibilityisthatyouindicatethatthecolorofeachparticlemustbedifferent,pickedfromarangeofcolors.Youcaneithergivearangeinred,greenandblue,orarangeinhue,saturation,andvalue.

Defaultthecoloriswhite.Whenyouuseaspritewithitsowncolors,thisisnormallywhatyouwantandnocolorneedstobespecified.

part_type_color1(ind,color1)Indicatesasinglecolortobeusedfor

theparticle.part_type_color2(ind,color1,color2)Specifiestwocolorsbetweenwhichthecolorisinterpolated.part_type_color3(ind,color1,color2,color3)Similarbutthistimethecolorisinterpolatedbetweenthreecolorsthatrepresentthecoloratthestart,half-way,andattheend.part_type_color_mix(ind,color1,color2)Withthisfunctionyouindicatethattheparticleshouldgetacolorthatisarandommixtureofthetwoindicatedcolors.Thiscolorwillremainfixedoverthelifetimeoftheparticle.part_type_color_rgb(ind,rmin,rmax,gmin,gmax,bmin,bmax)Canbeusedtoindicatethateachparticlemusthaveafixedcolorbutchoosenfromarange.Youspecifyarangeinthered,green,andbluecomponentofthecolor(eachbetween0and255).part_type_color_hsv(ind,hmin,hmax,smin,smax,vmin,vmax)Canbeusedtoindicatethateachparticlemusthaveafixedcolorbutchoosenfromarange.Youspecifyarangeinthehuesaturationandvaluecomponentofthecolor(eachbetween0and255).

Besidesthecoloryoucanalsogiveanalphatransparencyvalue.Thebuilt-inparticleshapesalreadyhavesomealphatransparencybutyoucanusethesesettingstoe.g.maketheparticlevanishoveritslifetime.

part_type_alpha1(ind,alpha1)Setsasinglealphatransparencyparameter(0-1)fortheparticletype.part_type_alpha2(ind,alpha1,alpha2)Similarbutthistimeastartandendvaluearegivenandthealphavalueisinterpolatedbetweenthem.part_type_alpha3(ind,alpha1,alpha2,alpha3)Thistimethreevaluesaregivenbetweenwhichthealphatransparencyisinterpolated.

Normallyparticlesareblendedwiththebackgroundinthesamewayassprites.Butitisalsopossibletouseadditiveblending.Thisgivesinparticularagreateffectforexplosion.

part_type_blend(ind,additive)Setswhethertouseadditiveblending(1)ornormalblending(0)fortheparticletype.

Lifeanddeath

Particlesliveforalimitedamountoftime,theirlifetime.Afterthistheydisappear.Lifetimeismeasuredinsteps.Youcanindicatethelifetime(orarangeoflifetimes)foreachparticletype.Particlescancreatenewparticlesofdifferenttypes.Therearetwowaysforthis.Theycancreatenewparticlesineachsteportheycancreateparticleswhentheydie.Becarefulthatthetotalnumberofparticlesdoesnotgettoohigh.

part_type_life(ind,life_min,life_max)Setsthelifetimeboundsfortheparticletype.(Defaultbothare100.)part_type_step(ind,step_number,step_type)Setsthenumberandtypeofparticlesthatmustbegeneratedineachstepfortheindicatedparticletype.Ifyouuseanegativevalue,ineachstepaparticleisgeneratedwithachance-1/number.Soforexamplewithavalueof-5aparticleisgeneratedonaverageonceevery5steps.part_type_death(ind,death_number,death_type)Setsthenumberandtypeofparticlesthatmustbegeneratedwhenaparticleoftheindicatedtypedies.Againyoucanusenegativenumberstocreateaparticlewithaparticularchance.Notethattheseparticlesareonlycreatedwhentheparticlediesattheendofitslife,notwhenitdiesbecauseofadestroyer(seebelow).

Particlemotion

Particlescanmoveduringtheirlifetime.Theycangetaninitialspeed(orrangeofspeeds)anddirection,andthespeedanddirectioncanchangeovertime.Alsogravitycanbedefinedthatpullstheparticlesinaparticulardirection.Thefollowingfunctionsexistforthis:

part_type_speed(ind,speed_min,speed_max,speed_incr,speed_wiggle)

Setsthespeedpropertiesfortheparticletype.(Defaultallvaluesare0.)Youspecifyaminimalandmaximalspeed.Arandomvaluebetweenthegivenboundsischosenwhentheparticleiscreated.YoucanindicateaspeedincreaseineachstepUseanegativenumbertoslowtheparticledown(thespeedwillneverbecome

smallerthan0).Finallyyoucanindicatesomeamountofwigglingofthespeed.part_type_direction(ind,dir_min,dir_max,dir_incr,dir_wiggle)

Setsthedirectionpropertiesfortheparticletype.(Defaultallvaluesare0.)Againyouspecifyarangeofdirections(incounterclockwisedegrees;0indicatedamotiontotheright).Forexample,tolettheparticlemoveinarandomdirectionchoose0and360asvalues.Youcanspecifyanincreaseindirectionforeachstep,andanamountofwiggling.part_type_gravity(ind,grav_amount,grav_dir)Setsthegravitypropertiesfortheparticletype.(Defaultthereisnogravity.)Youspecifytheamountofgravitytobeaddedineachstepandthedirection.E.g.use270foradownwardsdirection.

Particlesystems

Particlesliveinparticlesystems.Sotohaveparticlesinyourgameyouneedtocreateoneormoreparticlesystems.Therecanbedifferentparticlesystems(butpreferablykeeptheirnumbersmall).Forexample,ifyourgamehasanumberofballsandeachballshouldhaveatailofparticles,mostlikelyeachballhasitsownparticlesystem.Theeasiestwaytodealwithparticlesystemsistocreateoneandthencreateparticlesinit,usingtheparticletypesyouspecifiedbefore.But,aswewillseebelow,particlesystemscancontainemittersthatautomaticallyproduceparticles,attractorsthatattractthem,anddestroyersthatdestroythem.

Onceparticlesareaddedtoaparticlesystemtheyareautomaticallyupdatedeachstepanddrawn.Nofurtheractionisrequired.Tomakeitpossiblethatparticlesaredrawn,behind,infrontof,orbetweenobjectinstances,eachparticlesystemhasadepth,similartoinstancesandtiles.

Particlesystemswillliveonforeveraftertheyarecreated.Soevenifyouchangeroomorrestartthegame,thesystemsandtheparticlesremain.Soyoubettermakesureyoudestroythemonceyounolongerneedthem.

Thefollowingbasicfunctionsdealwithparticlesystems:

part_system_create()Createsanewparticlesystem.Itreturnstheindexofthesystem.Thisindexmustbeusedinallcallsbelowtosetthepropertiesoftheparticlesystem.part_system_destroy(ind)Destroystheparticlesystemind.Callthisifyoudon'tneeditanymoretosavespace.part_system_exists(ind)Returnswhethertheindicatedparticlesystemexists.part_system_clear(ind)Clearstheparticlesystemindtoitsdefaultsettings,removingallparticlesandemitterandattractorsinit.part_system_draw_order(ind,oldtonew)Setstheorderinwhichthe

particlesystemdrawstheparticles.Whenoldtonewistruetheoldestparticlesaredrawnfirstandtheneweronelieontopofthem(default).Otherwisethenewestparticlesaredrawnfirst.Thiscangiveratherdifferenteffects.part_system_depth(ind,depth)Setsthedepthoftheparticlesystem.Thiscanbeusedtolettheparticlesappearbehind,infrontof,orinbetweeninstances.part_system_position(ind,x,y)Setsthepositionwheretheparticlesystemisdrawn.Thisisnormallynotnecessarybutifyouwanttohaveparticlesatapositionrelativetoamovingobject,youcansetthepositione.g.tothatobject.

Asindicatedabove,theparticlesystemisautomaticallyupdatedanddrawn.Butsometimesthisisnotwhatyouwant.Tofacilitatethis,youcanswitchoffautomaticupdatingordrawingandthendecideyourselfwhentoupdateordrawtheparticlesystem.Forthisyoucanusethefollowingfunctions:

part_system_automatic_update(ind,automatic)Indicateswhethertheparticlesystemmustbeupdatedautomatically(1)ornot(0).Defaultis1.part_system_automatic_draw(ind,automatic)Indicateswhethertheparticlesystemmustbedrawnautomatically(1)ornot(0).Defaultis1.part_system_update(ind)Thisfunctionsupdatesthepositionofallparticlesinthesystemandletstheemitterscreateparticles.Youonlyhavetocallthiswhenupdatingisnotautomatic.(Althoughsometimesitisalsousefultocallthisfunctionacoupleoftimetogetthesystemgoing.)part_system_drawit(ind)Thisfunctionsdrawstheparticlesinthesystem.Youonlyhavetocallthiswhendrawingisnotautomatic.Itshouldbecalledinthedraweventofsomeobject.

Thefollowingfunctionsdealwithparticlesinaparticlesystems:

part_particles_create(ind,x,y,parttype,number)Thisfunctionscreatesnumberparticlesoftheindicatedtypeatpostion(x,y)inthesystem.

part_particles_create_color(ind,x,y,parttype,color,number)Thisfunctionscreatesnumberparticlesoftheindicatedtypeatpostion(x,y)inthesystemwiththeindicatedcolor.Thisisonlyusefulwhentheparticletypedefinesasinglecolor(ordoesnotdefineacoloratall).part_particles_clear(ind)Thisfunctionsremovesallparticlesinthesystem.part_particles_count(ind)Thisfunctionsreturnsthenumberofparticlesinthesystem.

Emitters

Emitterscreateparticles.Theycaneithercreateacontinuousstreamofparticlesorcanburstoutanumberofparticleswhenusingtheappropriatefunction.Aparticlesystemcanhaveanarbitrarynumberofemitters.Anemitterhasthefollowingproperties:

xmin,xmax,ymin,ymaxindicatetheextendoftheregioninwhichtheparticlesaregenerated.shapeindicatestheshapeoftheregion.Itcanhavethefollowingvalues:

ps_shape_rectangle

ps_shape_ellipse

ps_shape_diamond

ps_shape_line

distributionindicatesthedistributionusedtogeneratetheparticles.Itcanhavethefollowingvalues:

ps_distr_linearindicatesalineardistribution,thatiseverywhereintheregionthechanceisequalps_distr_gaussianindicatesaGaussiandistributioninwhichmoreparticlesaregeneratedinthecenterthanatthesidesoftheregionps_distr_invgaussianindicatesaninverseGaussiandistributioninwhichmoreparticlesaregeneratedatthesidesoftheregionthaninthecenter

particletypeindicatesthetypeofparticlesbeinggeneratednumberindicatesthenumberofparticlesgeneratedineachstep.Ifsmallerthan0,ineachstepaparticleisgeneratedwithachance-1/number.Soforexamplewithavalueof-5aparticleisgeneratedonaverageonceevery5steps.

Thefollowingfunctionsareavailabletosettheemittersandtoletthemcreateparticles.Notethateachofthemgetstheindexoftheparticlesystemtowhichitbelongsasafirstargument.

part_emitter_create(ps)Createsanewemitterinthegivenparticle

system.Itreturnstheindexoftheemitter.Thisindexmustbeusedinallcallsbelowtosetthepropertiesoftheemitter.part_emitter_destroy(ps,ind)Destroysemitterindintheparticlesystem.Callthisifyoudon'tneeditanymoretosavespace.part_emitter_destroy_all(ps)Destroysallemittersintheparticlesystemthathavebeencreated.part_emitter_exists(ps,ind)Returnswhethertheindicatedemitterexistsintheparticlesystem.part_emitter_clear(ps,ind)Clearstheemitterindtoitsdefaultsettings.part_emitter_region(ps,ind,xmin,xmax,ymin,ymax,shape,distribution)

Setstheregionanddistributionfortheemitter.part_emitter_burst(ps,ind,parttype,number)Burstsoncenumberparticlesoftheindicatedtypefromtheemitter.part_emitter_stream(ps,ind,parttype,number)Fromthismomentoncreatenumberparticlesoftheindicatedtypefromtheemitterineverystep.Ifyouindicateanumbersmallerthan0ineachstepaparticleisgeneratedwithachanceof-1/number.Soforexamplewithavalueof-5aparticleisgeneratedonaverageonceevery5steps.

Attractors

Besidesemittersaparticlesystemcanalsocontainattractors.Anattractorattractstheparticles(orpushesthemaway).Aparticlesystemcanhavemultipleattractors.Youarethoughrecommendedtousefewofthesebecausetheywillslowdowntheprocessingoftheparticles.Anattractorhasthefollowingproperties:

x,yindicatethepositionoftheattractor.forceindicatestheattractingforceoftheattractor.Howtheforceactsontheparticlesdependsonthefollowingparameters.distindicatesthemaximaldistanceatwhichtheattractorhaseffect.Onlyparticlescloserthatthisdistancetotheattractorwillbeattracted.kindindicatesthekindofattractor.Thefollowingvaluesexist

ps_force_constantindicatesthattheforceisconstantindependentofthedistance.ps_force_linearindicatesalinearlygrowingforce.Atthemaximaldistancetheforceis0whileatthepositionoftheattractoritattainsthegivenvalue.ps_force_quadraticindicatesthattheforcegrowsquadratic.

additiveindicateswhethertheforceisaddedtothespeedanddirectionineachstep(true)oronlyappliedtothepositionoftheparticle(false).Whenadditivetheparticlewillacceleratetowardstheattractorwhilewithanon-additiveforceitwillmovetherewithconstantspeed.

Thefollowingfunctionsexisttodefineattractors.Notethateachofthemgetstheindexoftheparticlesystemtowhichitbelongsasafirstargument.

part_attractor_create(ps)Createsanewattractorinthegivenparticlesystem.Itreturnstheindexoftheattractor.Thisindexmustbeusedinallcallsbelowtosetthepropertiesoftheattractor.part_attractor_destroy(ps,ind)Destroysattractorindintheparticlesystem.Callthisifyoudon'tneeditanymoretosavespace.

part_attractor_destroy_all(ps)Destroysallattractorsintheparticlesystemthathavebeencreated.part_attractor_exists(ps,ind)Returnswhethertheindicatedattractorexistsintheparticlesystem.part_attractor_clear(ps,ind)Clearstheattractorindtoitsdefaultsettings.part_attractor_position(ps,ind,x,y)Setsthepositionofattractorindto(x,y).part_attractor_force(ps,ind,force,dist,kind,aditive)Setstheforceparametersofattractorind.

Destroyers

Destroyersdestroyparticleswhentheyappearintheirregion.Aparticlesystemcanhaveanarbitrarynumberofdestroyers.Adestroyerhasthefollowingproperties:

xmin,xmax,ymin,ymaxindicatestheextentoftheregioninwhichtheparticlesaredestroyed.shapeindicatestheshapeoftheregion.Itcanhavethefollowingvalues:

ps_shape_rectangle

ps_shape_ellipse

ps_shape_diamond

Thefollowingfunctionsareavailabletosetthepropertiesofthedestroyers.Notethateachofthemgetstheindexoftheparticlesystemtowhichitbelongsasafirstargument.

part_destroyer_create(ps)Createsanewdestroyerinthegivenparticlesystem.Itreturnstheindexofthedestroyer.Thisindexmustbeusedinallcallsbelowtosetthepropertiesofthedestroyer.part_destroyer_destroy(ps,ind)Destroysdestroyerindintheparticlesystem.Callthisifyoudon'tneeditanymoretosavespace.part_destroyer_destroy_all(ps)Destroysalldestroyersintheparticlesystemthathavebeencreated.part_destroyer_exists(ps,ind)Returnswhethertheindicateddestroyerexistsintheparticlesystem.part_destroyer_clear(ps,ind)Clearsthedestroyerindtoitsdefaultsettings.part_destroyer_region(ps,ind,xmin,xmax,ymin,ymax,shape)Setstheregionforthedestroyer.

Deflectors

Deflectorsdeflectparticleswhentheyappearintheirregion.Notethatonlythepositionoftheparticleistakenintoaccountnotitsspriteorsize.Aparticlesystemcanhaveanarbitrarynumberofdeflectors.Adeflectorhasthefollowingproperties:

xmin,xmax,ymin,ymaxindicatestheextentoftheregioninwhichtheparticlesaredeflected.kindindicatesthekindofdeflector.Itcanhavethefollowingvalues:

ps_deflect_horizontaldeflectstheparticlehorizontally;typicallyusedforverticalwallsps_deflect_verticaldeflectstheparticlevertically;typicallyusedforhorizontalwalls

frictiontheamountoffrictionasaresultoftheimpactwiththedeflector.Thehigherthisamountthemoretheparticleissloweddownonimpact.

Thefollowingfunctionsareavailabletosetthepropertiesofthedeflector.Notethateachofthemgetstheindexoftheparticlesystemtowhichitbelongsasafirstargument.

part_deflector_create(ps)Createsanewdeflectorinthegivenparticlesystem.Itreturnstheindexofthedeflector.Thisindexmustbeusedinallcallsbelowtosetthepropertiesofthedeflector.part_deflector_destroy(ps,ind)Destroysdeflectorindintheparticlesystem.Callthisifyoudon'tneeditanymoretosavespace.part_deflector_destroy_all(ps)Destroysalldeflectorsintheparticlesystemthathavebeencreated.part_deflector_exists(ps,ind)Returnswhethertheindicateddeflectorexistsintheparticlesystem.part_deflector_clear(ps,ind)Clearsthedeflectorindtoitsdefaultsettings.part_deflector_region(ps,ind,xmin,xmax,ymin,ymax)Setstheregionforthedeflector.part_deflector_kind(ps,ind,kind)Setsthekindforthedeflector.

part_deflector_friction(ps,ind,friction)Setsthefrictionforthedeflector.

Changers

Changerschangecertainparticleswhentheyappearintheirregion.Aparticlesystemcanhaveanarbitrarynumberofchangers.Achangerhasthefollowingproperties:

xmin,xmax,ymin,ymaxindicatestheextentoftheregioninwhichtheparticlesarechanged.shapeindicatestheshapeoftheregion.Itcanhavethefollowingvalues:

ps_shape_rectangle

ps_shape_ellipse

ps_shape_diamond

parttype1indicatestheparticletypethatischanged.parttype2indicatestheparticletypeintowhichitischanged.kindindicatesthekindofchanger.Itcanhavethefollowingvalues:

ps_change_motiononlychangesthemotionparametersoftheparticle,notthecolorandshapeorlifetimesettings.ps_change_shapeonlychangestheshapeparameterslikesizeandcolorandshape.ps_change_allchangesallparameters,thisbasicallymeansthattheparticleisdestroyedandanewoneofthenewtypeiscreated.

Thefollowingfunctionsareavailabletosetthepropertiesofthechanger.Notethateachofthemgetstheindexoftheparticlesystemtowhichitbelongsasafirstargument.

part_changer_create(ps)Createsanewchangerinthegivenparticlesystem.Itreturnstheindexofthechanger.Thisindexmustbeusedinallcallsbelowtosetthepropertiesofthechanger.part_changer_destroy(ps,ind)Destroyschangerindintheparticlesystem.Callthisifyoudon'tneeditanymoretosavespace.part_changer_destroy_all(ps)Destroysallchangersintheparticlesystemthathavebeencreated.part_changer_exists(ps,ind)Returnswhethertheindicatedchanger

existsintheparticlesystem.part_changer_clear(ps,ind)Clearsthechangerindtoitsdefaultsettings.part_changer_region(ps,ind,xmin,xmax,ymin,ymax,shape)Setstheregionforthechanger.part_changer_types(ps,ind,parttype1,parttype2)Setswhichparticletypethechangermustchangeintowhatothertype.part_changer_kind(ps,ind,kind)Setsthekindforthechanger.

FireworkExample

Hereisanexampleofaparticlesystemthatcreatesfireworks.Thefireworkusestwoparticletypes:onethatformstherocketandonethatformstheactualfireworks.Therocketgeneratesthefireworkparticleswhenitdies.Wealsogenerateoneemitterintheparticlesystemthatregularlystreamoutrocketparticlesalongthebottomofthescreen.Tomakethisworkyouneedanobject.Initscreationeventweplacethefollowingcodethatcreatestheparticletypes,particlesystem,andtheemitter:

{

//maketheparticlesystem

ps=part_system_create();

//thefireworkparticles

pt1=part_type_create();

part_type_shape(pt1,pt_shape_flare);

part_type_size(pt1,0.1,0.2,0,0);

part_type_speed(pt1,0.5,4,0,0);

part_type_direction(pt1,0,360,0,0);

part_type_color1(pt1,c_red);

part_type_alpha2(pt1,1,0.4);

part_type_life(pt1,20,30);

part_type_gravity(pt1,0.2,270);

//therocket

pt2=part_type_create();

part_type_shape(pt2,pt_shape_sphere);

part_type_size(pt2,0.2,0.2,0,0);

part_type_speed(pt2,10,14,0,0);

part_type_direction(pt2,80,100,0,0);

part_type_color2(pt2,c_white,c_gray);

part_type_life(pt2,30,60);

part_type_gravity(pt2,0.2,270);

part_type_death(pt2,150,pt1);//createthefireworkondeath

//createtheemitter

em=part_emitter_create(ps);

part_emitter_region(ps,em,100,540,480,490,ps_shape_rectangle,ps_distr_linear);

part_emitter_stream(ps,em,pt2,-4);//createoneeveryfoursteps

}

Thatwilldothetrick.Youmightwanttomakesuretheparticlesystem(andmaybeparticletypes)aredestroyedwhenmovingtoanotherroom,otherwisethefireworkwillcontinueforever.

Multiplayergames


Playinggamesagainstthecomputerisfun.Butplayinggamesagainstotherhumanplayerscanbeevenmorefun.Itisalsorelativelyeasytomakesuchgamesbecauseyoudon'thavetoimplementcomplicatedcomputeropponentAI.Youcanofcoursesitwithtwoplayersbehindthesamemonitorandusedifferentkeysorotherinputdevices,butitisalotmoreinterestingwheneachplayercansitbehindhisowncomputer.Orevenbetter,oneplayersitsontheothersideoftheocean.GameMakerhasmultiplayersupport.Pleaserealizethatcreatingeffectivemultiplayergamesthatsynchronizewellandhavenolatencyisadifficulttask.Thischaptergivesabriefdescriptionofthepossibilities.Onthewebsiteatutorialisavailablewithmoreinformation.

Informationonmultiplayergamescanbefoundinthefollowingpages:

SettingupaConnectionCreatingandJoiningSessionsPlayersSharedDataMessages

Settingupaconnection

Fortwocomputertocommunicatetheywillneedsomeconnectionprotocol.Likemostgames,GameMakeroffersfourdifferenttypesofconnections:IPX,TCP/IP,Modem,andSerial.TheIPXconnection(tobemoreprecise,itisaprotocol)isalmostcompletelytransparent.Itcanbeusedtoplaygameswithotherpeopleonthesamelocalareanetwork.Itneedstobeinstalledonyourcomputertobeused.(Ifitdoesnotwork,consultthedocumentationofWindows.OrgototheNetworkiteminthecontrolpanelofWindowsandaddtheIPXprotocol.)TCP/IPistheinternetprotocol.Itcanbeusedtoplaywithotherplayersanywhereontheinternet,assumingyouknowtheirIPaddress.Onalocalnetworkyoucanuseitwithoutprovidingaddresses.Amodemconnectionismadethroughthemodem.Youhavetoprovidesomemodemsettings(aninitializationstringandaphonenumber)touseit.Finally,whenusingaserialline(adirectconnectionbetweenthecomputers)youneedtoprovideanumberofportsettings.TherearefourGMLfunctionsthatcanbeusedforinitializingtheseconnections:

mplay_init_ipx()initializesanIPXconnection.mplay_init_tcpip(addr)initializesaTCP/IPconnection.addrisastringcontainingthewebaddressorIPaddress,e.g.'www.gameplay.com'or'123.123.123.12',possiblyfollowedbyaportnumber(e.g.':12').Onlywhenjoiningasession(seebelow)doyouneedtoprovideanaddress.Onalocalareanetworknoaddressesarenecessary.mplay_init_modem(initstr,phonenr)initializesamodemconnection.initstristheinitializationstringforthemodem(canbeempty).phonenrisastringthatcontainsthephonenumbertoring(e.g.'0201234567').Onlywhenjoiningasession(seebelow)doyouneedtoprovideaphonenumber.mplay_init_serial(portno,baudrate,stopbits,parity,flow)

initializesaserialconnection.portnoistheportnumber(1-4).baudrateisthebaudratetobeused(100-256K).stopbitsindicatesthenumberofstopbits(0=1bit,1=1.5bit,2=2bits).parity

indicatestheparity(0=none,1=odd,2=even,3=mark).Andflowindicatesthetypeofflowcontrol(0=none,1=xon/xoff,2=rts,3=dtr,4=rtsanddtr).Returnswhethersuccessful.Atypicalcallismplay_init_serial(1,57600,0,0,4).Give0asafirstargumenttoopenadialogfortheusertochangethesettings.

Yourgameshouldcalloneofthesefunctionsexactlyonce.Allfunctionsreportwhethertheyweresuccessful.Theyarenotsuccessfuliftheparticularprotocolisnotinstalledorsupportedbyyourmachine.Tocheckwhetherthereisasuccessfulconnectionavailableyoucanusethefollowingfunction

mplay_connect_status()returnsthestatusofthecurrentconnection.0=noconnection,1=IPXconnection,2=TCP/IPconnection,3=modemconnection,and4=serialconnection.

Toendtheconnectioncall

mplay_end()endsthecurrentconnection.

WhenusingaTCP/IPconnectionyoumightwanttotellthepersonyouwanttoplaythegamewithwhattheipaddressofyourcomputeris.Thefollowingfunctionhelpsyouhere:

mplay_ipaddress()returnstheIPaddressofyourmachine(e.g.'123.123.123.12')asastring.Youcane.g.displaythissomewhereonthescreen.Notethatthisroutineisslowsodon'tcallitallthetime.

Creatingandjoiningsessions

Whenyouconnecttoanetwork,therecanbemultiplegameshappeningonthesamenetwork.Wecallthesesessions.Thesedifferentsessionscancorrespondtodifferentgamesortothesamegame.Agamemustuniquelyidentifyitselfonthenetwork.Fortunately,GameMakerdoesthisforyou.Theonlythingyouhavetoknowisthatwhenyouchangethegameidintheoptionsformthisidentificationchanges.Inthiswayyoucanavoidthatpeoplewitholdversionsofyourgamewillplayagainstpeoplewithnewversions.

Ifyouwanttostartanewmultiplayergameyouneedtocreateanewsession.Forthisyoucanusethefollowingroutine:

mplay_session_create(sesname,playnumb,playername)createsanewsessiononthecurrentconnection.sesnameisastringindicatingthenameofthesession.playnumbisanumberthatindicatesthemaximalnumberofplayersallowedinthisgame(use0foranarbitrarynumber).playnameisyournameasplayer.Returnswhethersuccessful.

Oneinstanceofthegamemustcreatethesession.Theotherinstance(s)ofthegameshouldjointhissession.Thisisslightlymorecomplicated.Youfirstneedtolookatwhatsessionsareavailableandthenchoosetheonetojoin.Therearethreeimportantroutinesforthis:

mplay_session_find()searchesforallsessionsthatstillacceptplayersandreturnsthenumberofsessionsfound.mplay_session_name(numb)returnsthenameofsessionnumbernumb(0isthefirstsession).Thisroutinecanonlybecalledaftercallingthepreviousroutine.mplay_session_join(numb,playername)makesyoujoinsessionnumbernumb(0isthefirstsession).playernameisyournameasaplayer.Returnswhethersuccessful.

Thereisonemoreroutinethatcanchangethesessionmode.Itshould

becalledbeforecreatingasession:

mplay_session_mode(move)setswhetherornottomovethesessionhosttoanothercomputerwhenthehostends.moveshouldeitherbetrueorfalse(thedefault).

Tocheckthestatusofthecurrentsessionyoucanusethefollowingfunction

mplay_session_status()returnsthestatusofthecurrentsession.0=nosession,1=createdsession,2=joinedsession.

Aplayercanstopasessionusingthefollowingroutine:

mplay_session_end()endsthesessionforthisplayer.

Players

Eachinstanceofthegamethatjoinsasessionisaplayer.Asindicatedabove,playershavenames.Therearethreeroutinesthatdealwithplayers.

mplay_player_find()searchesforallplayersinthecurrentsessionandreturnsthenumberofplayersfound.mplay_player_name(numb)returnsthenameofplayernumbernumb(0isthefirstplayer,whichisalwaysyourself).Thisroutinecanonlybecalledaftercallingthepreviousroutine.mplay_player_id(numb)returnstheuniqueidofplayernumbernumb(0isthefirstplayer,whichisalwaysyourself).Thisroutinecanonlybecalledaftercallingthefirstroutine.Thisidisusedinsendingandreceivingmessagestoandfromindividualplayers.

Shareddata

Shareddatacommunicationisprobablytheeasiestwaytosynchronizethegame.Allcommunicationisshieldedfromyou.Thereisasetof1000000valuesthatarecommontoallentitiesofthegame(preferablyonlyusethefirstfewtosavememory).Eachentitycansetvaluesandreadvalues.GameMakermakessurethateachentityseesthesamevalues.Avaluecaneitherbearealorastring.Therearejusttworoutines:

mplay_data_write(ind,val)writevalueval(stringorreal)intolocationind(indbetween0and1000000).mplay_data_read(ind)returnsthevalueinlocationind(indbetween0and1000000).Initiallyallvaluesare0.

Tosynchronizethedataonthedifferentmachinesyoucaneitheruseaguaranteedmodethatmakessurethatthechangearrivesontheothermachine(butwhichisslow)ornon-guaranteed.Tochangethisusethefollowingroutine:

mplay_data_mode(guar)setswhetherornottouseguaranteedtransmissionforshareddata.guarshouldeitherbetrue(thedefault)orfalse.

Messages

ThesecondcommunicationmechanismthatGameMakersupportsisthesendingandreceivingofmessages.Aplayercansendmessagestooneorallotherplayers.Playerscanseewhethermessageshavearrivedandtakeactionaccordingly.Messagescanbesentinaguaranteedmodeinwhichyouaresuretheyarrive(butthiscanbeslow)orinanon-guaranteedmode,whichisfaster.

Thefollowingmessagingroutinesexist:

mplay_message_send(player,id,val)sendsamessagetotheindicatedplayer(eitheranidentifieroraname;use0tosendthemessagetoallplayers).idisanintegermessageidentifierandvalisthevalue(eitherarealorastring).Themessageissentinnon-guaranteedmode.Ifvalcontainsastringthemaximalstringlengthallowedis30000characters.mplay_message_send_guaranteed(player,id,val)sendsamessagetotheindicatedplayer(eitheranidentifieroraname;use0tosendthemessagetoallplayers).idisanintegermessageidentifierandvalisthevalue(eitherarealorastring).Thisisaguaranteedsend.Ifvalcontainsastringthemaximalstringlengthallowedis30000characters.mplay_message_receive(player)receivesthenextmessagefromthemessagequeuethatcamefromtheindicatedplayer(eitheranidentifieroraname).Use0formessagesfromanyplayer.Theroutinereturnswhethertherewasindeedanewmessage.Ifsoyoucanusethefollowingroutinestogetitscontents:mplay_message_id()Returnstheidentifierofthelastreceivedmessage.mplay_message_value()Returnsthevalueofthelastreceivedmessage.mplay_message_player()Returnstheplayerwhosentthelastreceivedmessage.mplay_message_name()Returnsthenameoftheplayerwhosentthe

lastreceivedmessage.mplay_message_count(player)Returnsthenumberofmessagesleftinthequeuefromtheplayer(use0tocountallmessage).mplay_message_clear(player)Removesallmessagesleftinthequeuefromtheplayer(use0toremoveallmessage).

Afewremarksarepertinenthere.Firstofall,ifyouwanttosendamessagetoaparticularplayeronly,youwillneedtoknowtheplayer'suniqueid.Asindicatedearlieryoucanobtainthiswiththefunctionmplay_player_id().Thisplayeridentifierisalsousedwhenreceivingmessagesfromaparticularplayer.Alternatively,youcangivethenameoftheplayerasastring.Ifmultipleplayershavethesamename,onlythefirstwillgetthemessage.

Secondly,youmightwonderwhyeachmessagehasanintegeridentifier.Thereasonisthatthishelpsyourapplicationtosenddifferenttypesofmessages.Thereceivercancheckthetypeofmessageusingtheidandtakeappropriateactions.(Becausemessagesarenotguaranteedtoarrive,sendingidandvalueindifferentmessageswouldcauseseriousproblems.)

UsingDLL's


Pleasenotethatsinceversion7thereisanewextensionmechanisminGameMaker.Youarestronglyencouragedtousethatextensionmechanism,ratherthanthefunctionsdescribedinthissection.Seehttp://www.yoyogames.com/extensionsfordetails.Thesefunctionsaremainlyleftinforcompatibilitywiththepast.

InthosecaseswerethefunctionalityofGMLisnotenoughforyourwishes,youcanactuallyextendthepossibilitiesbyusingplug-ins.Aplug-incomesintheformofaDLLfile(aDynamicLinkLibrary).InsuchaDLLfileyoucandefinefunctions.SuchfunctionscanbeprogrammedinanyprogramminglanguagethatsupportsthecreationofDLL's(e.g.Delphi,C,C++,etc.)Youwillthoughneedtohavesomeprogrammingskilltodothis.Plug-infunctionsmusthaveaspecificformat.Theycanhavebetween0and16arguments,eachofwhichcaneitherbearealnumber(doubleinC)oranull-terminatedstring.(Formorethan4arguments,onlyrealargumentsaresupportedatthemoment.)Theymustreturneitherarealoranull-terminatedstring.

InDelphiyoucreateaDLLbyfirstchoosingNewfromtheFilemenuandthenchoosingDLL.HereisanexampleofaDLLyoucanusewithGameMakerwritteninDelphi.(NotethatthisisDelphicode,notGMLcode!)

libraryMyDLL;

usesSysUtils,Classes;

functionMyMin(x,y:double):double;cdecl;

begin

ifx<ythenResult:=xelseResult:=y;

end;

varres:array[0..1024]ofchar;

functionDoubleString(str:PChar):PChar;cdecl;

http://www.yoyogames.com/extensions

begin

StrCopy(res,str);

StrCat(res,str);

Result:=res;

end;

exportsMyMin,DoubleString;

begin

end.

ThisDLLdefinestwofunctions:MyMinthattakestworealargumentsandreturnstheminimumofthetwo,andDoubleStringthatdoublesthestring.Notethatyouhavetobecarefulwithmemorymanagement.ThatiswhyIdeclaredtheresultingstringglobal.Alsonoticetheuseofthecdeclcallingconvention.Youcaneitherusecdeclorstdcallcallingconventions.OnceyoubuildtheDLLinDelphiyouwillgetafileMyDLL.DLL.Thisfilemustbeplacedintherunningdirectoryofyourgame.(OranyotherplacewhereWindowscanfindit.)

TousethisDLLinGameMakeryoufirstneedtospecifytheexternalfunctionsyouwanttouseandwhattypeofargumentstheytake.ForthisthereisthefollowingfunctioninGML:

external_define(dll,name,calltype,restype,argnumb,arg1type,arg2type,

...)Definesanexternalfunction.dllisthenameofthedllfile.nameisthenameofthefunctions.calltypeisthecallingconventionused.Forthisuseeitherdll_cdeclordll_stdcall.restypeisthetypeoftheresult.Forthisuseeitherty_realorty_string.argnumbisthenumberofarguments(0-16).Next,foreachargumentyoumustspecifyitstype.Forthisagainuseeitherty_realorty_string.Whentherearemorethan4argumentsallofthemmustbeoftypety_real.

Thisfunctionreturnstheidoftheexternalfunctionthatmustbeusedforcallingit.Sointheaboveexample,atthestartofthegameyouwouldusethefollowingGMLcode:

{

global.mmm=external_define('MyDLL.DLL','MyMin',dll_cdecl,

ty_real,2,ty_real,ty_real);

global.ddd=external_define('MyDLL.DLL','DoubleString',dll_cdecl,

ty_string,1,ty_string);

}

Nowwheneveryouneedtocallthefunctions,youusethefollowingfunction:

external_call(id,arg1,arg2,...)Callstheexternalfunctionwiththegivenid,andthegivenarguments.Youneedtoprovidethecorrectnumberofargumentsofthecorrecttype(realorstring).Thefunctionreturnstheresultoftheexternalfunction.

So,forexample,youwouldwrite:

{

aaa=external_call(global.mmm,x,y);

sss=external_call(global.ddd,'Hello');

}

Ifyoudon'tneedtousetheDLLanymoreyouhadbetterfreeit.

external_free(dll)FreestheDLLwiththegivenname.ThisisinparticularnecessaryifthegameshouldremovetheDLL.AslongastheDLLisnotfreeditcannotberemoved.Bestdothise.g.inanendofgameevent.

YoumightwonderhowtomakeafunctioninaDLLthatdoessomethinginthegame.Forexample,youmightwanttocreateaDLLthataddsinstancesofobjectstoyourgame.TheeasiestwayistoletyourDLLfunctionreturnastringthatcontainsapieceofGMLcode.ThisstringthatcontainsthepieceofGMLcanbeexecutedusingtheGMLfunction

execute_string(str,arg0,arg1,...)Executethepieceofcodeinthestringstrwiththeindicatedarguments.

AlternativelyyoucanlettheDLLcreateafilewithascriptthatcanbeexecuted(thisfunctioncanalsobeusedtolatermodifythebehaviorofagame).

execute_file(fname)Executethepieceofcodeinthefile.

Nowyoucancallanexternalfunctionandthenexecutetheresultingstring,e.g.asfollows:

{

ccc=external_call(global.ddd,x,y);

execute_string(ccc);

}

InsomerarecasesyourDLLmightneedtoknowthehandleofthemaingraphicswindowforthegame.ThiscanbeobtainedwiththefollowingfunctionandcanthenbepassedtotheDLL:

window_handle()Returnsthewindowhandleforthemainwindow.

NotethatDLLscannotbeusedinsecuremode.

UsingexternalDLLsisanextremelypowerfulmechanism.Butpleaseonlyuseitifyouknowwhatyouaredoing.

3DGraphics


GameMakerisaprogrammeantformaking2-dimensionalandisometricgames.Stillthereissomefunctionalitytocreate3-dimensionalgraphics.Beforeyoustartwiththisthoughthereareafewthingsyoumustunderstand.

The3DfunctionalityinGameMakerislimitedtothegraphicspart.Thereisnosupportforother3Dfunctionality.Onceyoustartusing3DgraphicsyoumightgetproblemswithotheraspectsofGameMaker,liketheviews,depthordering,etc.Thefunctionalityislimitedandhaslowprioritytobeextended.Sodon'texpectsupportfor3Dobjectmodels,etc.Whenyouusethe3Dfunctionality,thereareanumberofotherthingsthatcannolongerbeused.

Youcannotusebackgroundandforegroundsinyourroomsanymore.(Thereasonisthattheyaretiledtofilltheimagebutwithperspectiveprojectionsthisnolongerworkcorrectly).Youcannotusethemousepositionanymore.Themousewillnotbetransformedtothe3Dcoordinates.Youcanstillgetthepositionofthemouseonthescreen(intheview)butyouwillhavetodocalculationwiththisyourself(ornotusethemouseatall).Youcannotusetilesanymore.Tileswillmostlikelynolongermatchupcorrectly.Collisioncheckingstillusesthe2-dpositionsoftheinstancesintheroom.Sothereisnocollisiondetectionin3D.Sometimesyoucanstillusethis(ifyouusetheroomasarepresentationofaflatworld(e.g.forracingorFPSgames)butinothersituationsyouhavetodothingsyourself.

All3Dfunctionalityisthroughcode.YoumustberatherfluentwiththeGMLlanguage.AlsoyoumustreallyunderstandalotabouthowGameMakerworksotherwiseyouwillrunintotrouble.

Youmusthavesomebasicknowledgeabout3Dgraphics.InparticularIwillusetermslikeperspectiveprojections,hiddensurfaceremoval,lighting,andfog,withoutmuchexplanation.Thereisno3DmodellinginGameMaker.AlsoIdonotplanonaddingsupportforloading3Dmodels.Youmustworkcarefullytokeepareasonablespeed.Also,thingsarenotreallyoptimizedforspeed.

Ifthisdidnotdiscourageyou,readon.

Informationon3dgraphicscanbefoundinthefollowingpages:

Goingto3DmodeEasydrawingDrawingpolygonsin3DDrawingbasicshapesViewingtheworldTransformationsFogLightingCreatingmodelsFinalwords

Goingto3Dmode

Ifyouwanttouse3DmodeyoufirstneedtosetGameMakerin3Dmode.Youcanlaterswitchbackto2Dmodeifyouwant.Thefollowingtwofunctionsexistforthis.

d3d_start()Startusing3Dmode.Returnswhethersuccessful.d3d_end()Stopusing3Dmode.Returnswhethersuccessful.

Notethatallfunctionsrelatedto3Dmodestartwithd3d_.

Starting3Dmodewillresultinthefollowingchanges.Firstofallhiddensurfaceremovalisswitchedon(usinga16-bitz-buffer).Thismeansthatforeachpixelonthescreenonlythedrawingwiththesmallestz-value(=depthvalue)isdrawn.Ifinstanceshavethesamedepthitisunclearwhatwillhappenandyoucangetuglyeffects.Makesureinstancesthatmightoverlapdonothavethesamedepthvalue!

Secondly,thenormalorthographicprojectionisreplacedbyaperspectiveone.Thismeansthefollowing.Normallythesizeofinstancesonthescreenisindependentonitsdepth.Withaperspectiveprojectioninstancesthathaveagreaterdepthwillappearsmaller.Whenthedepthis0itisequaltotheoldsize(unlessyouchangetheprojection;seebelow).Theviewpointforthecameraisplacedatadistanceabovetheroom.(Thisdistanceisequaltothewidthoftheroom;thatgivesareasonabledefaultprojection.)Onlyinstancesinfrontofthecameraaredrawn.Sodon'tuseinstanceswithadepthsmallerthan0(oratleastnotsmallerthan-wwherewisthewidthoftheroomortheview).

Thirdly,theverticaly-coordinateisreversed.Whilenormallythe(0,0)positionisatthetop-leftoftheview,in3Dmodethe(0,0)positionisatthebottom-leftposition,asisnormalfor3-dimensionalviews.

Youcanactuallyswitchhiddensurfaceremoveandperspectiveprojectiononoroffusingthefollowingfunctions.

d3d_set_hidden(enable)Enableshiddensurfaceremoval(true)ordisablesit(false).d3d_set_perspective(enable)Enablestheuseofaperspectiveprojection(true)ordisablesit(false).

Easydrawing

Once3DmodehasbeenswitchedonyoucanuseGameMakerasyouareusedtoit(exceptfortheremarksmadeatthebeginning).Onlyobjectswillappearindifferentsizesbasedontheirdepthsetting.Youcanevenuseviews.Oneadditionalfunctioncanbeuseful.Ifyoudrawanumberofthingsinapieceofcodeyoumightwanttochangethedepthvaluebetweentheprimitivesyoudraw.Forthisyouuse:

d3d_set_depth(depth)Setsthedepthusedfordrawing.

Notethatatthemomentanewinstanceisdrawnthedepthisagainsettothedepthofthatinstance.

Drawingpolygonsin3D

Theproblemwithdrawingintheoldwayisthataspriteorpolygonalwaysliesinthexy-plane,thatis,allcornershavethesamedepth.Fortrue3Dyouwanttobeabletohaveverticesatdifferentdepths.Fromthismomentonwewilltalkaboutz-coordinateratherthandepth.Sowewanttospecifycoordinatesas(x,y,z)tuples.Forthistherearespecialversionoftheadvanceddrawingfunctions:

d3d_primitive_begin(kind)Starta3Dprimitiveoftheindicatedkind:pr_pointlist,pr_linelist,

pr_linestrip,pr_trianglelist,pr_trianglestriporpr_trianglefan.d3d_vertex(x,y,z)Addvertex(x,y,z)totheprimitive,usingthecolorandalphavaluesetbefore.d3d_vertex_color(x,y,z,col,alpha)Addvertex(x,y,z)totheprimitive,withitsowncolorandalphavalue.Thisallowsyoutocreateprimitiveswithsmoothlychangingcolorandalphavalues.d3d_primitive_end()Endthedescriptionoftheprimitive.Thisfunctionactuallydrawsit.

Forexample,todrawatetrahedron(threesidedpyramid)standingonthez=0planewithitstopatz=200,youcanusethefollowingcode:

{

d3d_primitive_begin(pr_trianglelist);

d3d_vertex(100,100,0);

d3d_vertex(100,200,0);

d3d_vertex(150,150,200);

d3d_vertex(100,200,0);

d3d_vertex(200,200,0);

d3d_vertex(150,150,200);

d3d_vertex(200,200,0);

d3d_vertex(100,100,0);

d3d_vertex(150,150,200);

d3d_vertex(100,100,0);

d3d_vertex(100,200,0);

d3d_vertex(200,200,0);

d3d_primitive_end();

}

Nowifyouwouldusethis,mostlikelyyouwouldjustseeatriangleonthescreenbecausethetopofthetetrahedronwillbebehinditfromtheviewpoint.Also,usingjustonecolor,itwouldbedifficulttoseethedifferentfaces.Belowwewillseewaystochangetheviewpoint.Assigningcolorscanbedoneasbeforebyaddeddraw_set_color(col)functioncallsbetweenthevertices.

Youcanalsousetexturedpoygonsin3D.Itworksexactlythesameasdescribedintheadvanceddrawingfunctionsinthedocumentation.Butthistimeyouneed3Dvariantsofthebasicfunctions.Onethingyoumustrealize.Inatexturetheposition(0,0)isthetop-leftcorner.Butoften,whenusingprojections(asindicatedbelow),thebottom-leftcorneris(0,0).Insuchacaseyoumightneedtoflipthetexturevertically.

d3d_primitive_begin_texture(kind,texid)Starta3Dprimitiveoftheindicatedkindwiththegiventexture.d3d_vertex_texture(x,y,z,xtex,ytex)Addvertex(x,y,z)totheprimitivewithposition(xtex,ytex)inthetexture,blendingwiththecolorandalphavaluesetbefore.d3d_vertex_texture_color(x,y,z,xtex,ytex,col,alpha)Addvertex(x,y,z)totheprimitivewithposition(xtex,ytex)inthetexture,blendingwithitsowncolorandalphavalue.d3d_primitive_end()Endthedescriptionoftheprimitive.Thisfunctionactuallydrawsit.

So,forexampleyoucanusethefollowingcodetodrawabackgroundimagethatdisappearsintothedistance

{

varttt;

ttt=background_get_texture(back);

d3d_primitive_begin_texture(pr_trianglefan,ttt);

d3d_vertex_texture(0,480,0,0,0);




d3d_primitive_end();

}

Atrianglehasafrontandabackside.Thefrontsideisdefinedtobethesidewheretheverticesaredefinedincounter-clockwiseorder.Normallybothsidesaredrawn.Butifyoumakeaclosedshapethisisawastebecausethebacksideofthetrianglecanneverbeseen.Inthiscaseyoucanswitchonbackfaceculling.Thissavesabouthalftheamountofdrawingtimebutitleavesyouwiththetaskofdefiningyourpolygonsintherightway.Thefollowingfunctionexists:

d3d_set_culling(cull)Indicatestostartbackfaceculling(true)orstopbackfaceculling(false).

Drawingbasicshapes

Anumberoffunctionsexistfordrawingbasicshapes,likeblocksandwalls.Notethattheseshapesalsoworkcorrectlywithbackfacecullingon.

d3d_draw_block(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat)Drawsablockinthecurrentcolorwiththeindicatedoppositecornersusingtheindicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.d3d_draw_cylinder(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat,closed,steps)

Drawsaverticalcylinderinthecurrentcolorintheindicatedboundingboxusingtheindicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.closedindicateswhethertoclosethetopandbottomofthecylinder.stepsindicateshowmanyrotationalstepsmustbetaken.Atypicalvalueis24.d3d_draw_cone(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat,closed,steps)

Drawsaverticalconeinthecurrentcolorintheindicatedboundingboxusingtheindicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.closedindicateswhethertoclosethetopandbottomofthecylinder.stepsindicateshowmanyrotationalstepsmustbetaken.Atypicalvalueis24.d3d_draw_ellipsoid(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat,steps)

Drawsanellipsoidinthecurrentcolorintheindicatedboundingboxusingtheindicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.stepsindicateshowmanyrotationalstepsmustbetaken.Atypicalvalueis24.d3d_draw_wall(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat)Drawsaverticalwallinthecurrentcolorwiththegivencornersusingthe

indicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.d3d_draw_floor(x1,y1,z1,x2,y2,z2,texid,hrepeat,vrepeat)Drawsa(slanted)floorinthecurrentcolorwiththegivencornersusingtheindicatedtexture.Use-1tonotuseatexture.hrepeatindicateshowoftenthetexturemustberepeatedalongthehorizontaledgeofeachface.vrepeatdoesthesamefortheverticaledge.

Thefollowingpieceofcodedrawstwoblocks:

{

varttt;

ttt=background_get_texture(back);

d3d_draw_block(20,20,20,80,40,200,ttt,1,1);

d3d_draw_block(200,300,-10,240,340,100,ttt,1,1);

}

Viewingtheworld

Defaultyoulookalongthenegativez-axistowardthemiddleoftheroom.Oftenin3Dgamesyouwanttochangehowyoulookattheworld.Forexample,inafirstpersonshooteryouprobablywanttohavethecameralookfromapositionabitabovethexy-planealongthexy-plane.Ingraphicstermsyouaresettingthecorrectprojection.Tochangethewayyoulookthefollowingtwofunctionsexist.

d3d_set_projection(xfrom,yfrom,zfrom,xto,yto,zto,xup,yup,zup)

Defineshowtolookintheworld.Youspecifythepointtolookfrom,thepointtolooktoandtheupvector.

Thisfunctionrequiressomeexplanation.Tosettheprojectionyoufirstneedthepositionyoulookfrom.Thisisindicatedbytheparameters(xfrom,yfrom,zfrom).Nextyoumustspecifythedirectionyoulookin.Thisisdonebygivingasecondpointtolooktowards.Thisisthepoint(xto,yto,zto).Finally,youcanstillrotatethecameraaroundthelinefromtheviewpointtothelookingpoint.Tospecifythiswemustgiveanupvector,thatis,thedirectionthatisupwardsinthecamera.Thisisgivenbythelastthreeparameters(xup,yup,zup).Letmegivenanexample.Tolookalongthexy-planeasinafirstpersonshooteryoucanuse

{

d3d_set_projection(100,100,10,200,100,10,0,0,1);

}

Soyoulookfrompoint(100,100)and10abovetheplaneinthedirectionof(200,100).Theupvectorpointsisthez-directionasrequired.Tomakethisslightlymorecomplicated,assumeyouhaveaninstanceinyourroomthatspecifiesthepositionofthecamera.Itwillhaveacurrent(x,y)positionandadirection(andmaybeevenaspeed).Youcannowspecifythisasyourcamerabyusingthefollowingcode:

{

with(obj_camera)

d3d_set_projection(x,y,10,

x+cos(direction*pi/180),y-sin(direction*pi/180),10,

0,0,1);

}

Thismightlookabitcomplicated.Welookfromthecameraposition(x,y),10abovetheground.Todetermineapointinthecorrectdirectionweneedtodoalittlearithmetic.Thispointisindicatedbythenextthreeparameters.Finallyweusetheupvectorasabove.

Oneimportantremark!WhenGameMakerstartsdrawingaroomitwillsettheviewpointbacktothedefaultposition.Sothefirstthingyoumustdowhendrawingthesceneissetistotheprojectionyouwant.Thismustbedoneinadrawingevent!

Thereisalsoanextendedversionofthefunctionabove:

d3d_set_projection_ext(xfrom,yfrom,zfrom,xto,yto,zto,xup,yup,zup,angle,aspect,znear,zfar)

Anextendedversionofthisfunctioninwhichyoualsospecifytheangledefiningthefieldofview,theaspectratiobetweenhorizontalandverticalsizeoftheview,andthenearandfarclippingplanes.

Theadditionalparametersworkasfollows.Ifyouspecifiedthecameraposition,pointtolookat,andupvector,youcanstillchangehowwidethelensofthecamerais.Thisiscalledthefieldofview.Areasonablevalueissomewherebetween40and45degrees.Butyoucanchangethisifyoulike.Nextyoucanspecifytheaspectratiobetweenthehorizontalandverticalprojection.Normallyyouwanttousethesameastheaspectrationoftheroomorview,e.g.640/480.Finallyyoucanindicatetheclippingplanes.Objectsthatarecloserthanzneartothecameraarenotdrawn.Similarforobjectsfurtherthanzfar.Itcanbeimportanttosettheseparameterstoreasonablevaluesbecausetheyalsoinfluencetheprecisionofthez-comparisons.Ifyoumaketherangetoolargetheprecisiongetsworse.Defaultweuse1and32000.znearmustbelargerthan0!

Sometimesyoutemporarilyneedanormalorthographicprojectionasisusedwhenthereisno3D.Oryouwanttoreturntothedefaultperspectiveprojection.Forthisyoucanusethefollowingfunctions:

d3d_set_projection_ortho(x,y,w,h,angle)Setsanormalorthographicprojectionoftheindicatedareaintheroom,rotatedovertheindicatedangle.d3d_set_projection_perspective(x,y,w,h,angle)Setsanormalperspectiveprojectionoftheindicatedareaintheroom,rotatedovertheindicatedangle.

Astandarduseforthisistodrawanoverlaytoe.g.showthescoreorotheraspects.Todosowesetanorthographicprojection.Wealsomusttemporarilyswitchoffhiddensurfaceremovalcausewewanttheinformationtobedrawnregardlessofthecurrentdepthvalue.Thefollowingexampleshowshowtocreateanoverlaywiththescore.

{

draw_set_color(c_black);

d3d_set_projection_ortho(0,0,room_width,room_height,0);

d3d_set_hidden(false);

draw_text(10,10,'Score:'+string(score));

d3d_set_hidden(true);

}

Transformations

Transformationallowyoutochangetheplacewherethingsaredrawnintheworld.Forexample,thefunctiontodrawblockscanonlydrawaxis-parallelblocks.Byfirstsettingarotationtransformationyoucancreaterotatedblocks.Alsospritesarealwaysdrawnparalleltothexy-plane.Bysettingatransformationyoucanchangethis.Therearetwotypesoffunctions:functionsthatsetthetransformationandfunctionsthataddtransformations.

d3d_transform_set_identity()Setsthetransformationtotheidentity(notransformation).d3d_transform_set_translation(xt,yt,zt)Setsthetransformationtoatranslationovertheindicatedvector.d3d_transform_set_scaling(xs,ys,zs)Setsthetransformationtoascalingwiththeindicatedamounts.d3d_transform_set_rotation_x(angle)Setsthetransformationtoarotationaroundthex-axiswiththeindicatedamount.d3d_transform_set_rotation_y(angle)Setsthetransformationtoarotationaroundthey-axiswiththeindicatedamount.d3d_transform_set_rotation_z(angle)Setsthetransformationtoarotationaroundthez-axiswiththeindicatedamount.d3d_transform_set_rotation_axis(xa,ya,za,angle)Setsthetransformationtoarotationaroundtheaxisindicatedbythevectorwiththeindicatedamount.d3d_transform_add_translation(xt,yt,zt)Addsatranslationovertheindicatedvector.d3d_transform_add_scaling(xs,ys,zs)Addsascalingwiththeindicatedamounts.d3d_transform_add_rotation_x(angle)Addsarotationaroundthex-axiswiththeindicatedamount.d3d_transform_add_rotation_y(angle)Addsarotationaroundthey-axiswiththeindicatedamount.d3d_transform_add_rotation_z(angle)Addsarotationaroundthez-axiswiththeindicatedamount.

d3d_transform_add_rotation_axis(xa,ya,za,angle)Addsarotationaroundtheaxisindicatedbythevectorwiththeindicatedamount.

Realizethatrotationandscalingarewithrespecttotheoriginoftheworld,notwithrespecttotheobjectthatistobedrawn.Iftheobjectisnotattheoriginitwillalsomovetoadifferentplace,whichisnotwhatwewant.Sotoe.g.rotateanobjectoveritsownx-axis,wemustfirsttranslateittotheorigin,nextrotateit,andfinallytranslateitbacktoitsposition.Thisiswhatthefunctionstoaddtransformationsarefor.

Thefollowingexamplesmightexplainthisbetter.Assumewehaveaspritesprthatwewanttodrawatposition(100,100,10).Wecanusethefollowingcodetodothis

{

d3d_transform_set_translation(100,100,10);

draw_sprite(spr,0,0,0);

d3d_transform_set_identity();

}

Notethatbecauseweuseatranslationweshouldnowdrawthespriteatposition(0,0).(Thisassumesthecurrentinstancehasadepthof0!Ifyouarenotsure,firstsetthedepth.)Ifwewouldusethisinourfirstpersonshooterwewouldnotseethesprite.Thereasonisthatitisstillparalleltothexy-plane.Wewanttorotateitover90degreesalongthex-axis(ory-axis).Soweneedtoaddarotation.Remembertheorder:wemustfirstrotatethespriteandthentranslateit.Sowecanusethefollowingcode.

{


d3d_transform_add_rotation_x(90);

d3d_transform_add_translation(100,100,10);

draw_sprite(spr,0,0,0);


}

Sometimesyoutemporarilywanttosavethecurrenttransformation,forexampletoaddanadditionaltransformationandthenrestoretheoldone(thisoftenhappenswhendrawinghierarchicalmodels).Tothisendyoucanpushthecurrenttransformationonastackandlaterpopitfromthe

stacktomakeitthecurrenttransformationagain.Thefollowingfunctionsexistforthis:

d3d_transform_stack_clear()Clearsthestackoftransformations.d3d_transform_stack_empty()Returnswhetherthetransformationstackisempty.d3d_transform_stack_push()Pushesthecurrenttransformationonthestack.Returnswhethertherewasroomonthestacktopushitthere(ifyouforgetpoppingtransformationyouatsomemomentwillrunoutofroomonthestack).d3d_transform_stack_pop()Popsthetoptransformationfromthestackandmakesitthecurrentone.Returnswhethertherewasatransformationonthestack.d3d_transform_stack_top()Makesthetoptransformationthecurrentone,butdoesnotremoveitfromthestack.Returnswhethertherewasatransformationonthestack.d3d_transform_stack_discard()Removesthetoptransformationfromthestackbutdoesnotmakeitthecurrentone.Returnswhethertherewasatransformationonthestack.

Usingtransformationisapowerfulmechanism.Butbecarefulandalwayssetthetransformationbacktotheidentityonceyouaredone.

Fog

Fogcanbeusedin3Dgamestomakeobjectsinthedistancelookblurredorevendisappear.Thishelpsincreatingatmosphereanditmakesitpossibletonotdrawobjectsthatarefaraway.Toenableordisablefogusethefollowingfunction:

d3d_set_fog(enable,color,start,end)Enablesordisablestheuseoffog.colorindicatesthefogcolor.startindicatesthedistanceatwhichfogmuststart.endindicatesthedistanceatwhichfogismaximalandnothingcanbeseenanymore.

Tobetterunderstandwhatishappening,thereareactuallytwotypesoffog,tablebasedfogandvertexbasedfog.Thefirsttypecalculatesfogvaluesonapixelbasis.Thesecondtypecalculatesthefogvalueforeachvertexandtheninterpolatesthese.Thefirsttypeisbetterbutnotalwayssupported.GameMakertriestousetablebasedfogwhensupportedandotherwiseusesvertexbasedfog(unlessnofogissupported).Notethatcertaingraphicscardindicatethattheycanhandletablebasedfogbutoffertheuserthepossibilitytoswitchthisoffintheadvanceddisplaysettings.Inthiscasetheresultmightbeablackscreen!

Lighting

Scenesyoudrawwiththefunctionsabovelookratherflatbecausethereisnolight.Thecolorifthefacesisequal,independentoftheirorientation.Tocreatemorerealisticallylookingscenesyoumustenablelightingandplacelightsatthecorrectplaces.Creatingcorrectlylitscenesisnoteasybuttheeffectisverygood.

Toenablelightingyoucanusethefollowingfunction;

d3d_set_lighting(enable)Enablesordisablestheuseoflighting.

Whenusinglighting,foreachvertexofapolygonthecolorisdetermined.Next,thecolorofinternalpixelsisbasedonthecolorofthesevertices.Therearetwowaysthiscanbedone:Eitherthewholepolygongetsthesamecolor,orthecolorissmoothlyinterpolatedoverthepolygon.Defaultsmoothshadingisused.Thiscanbechangedusingthefollowingfunction:

d3d_set_shading(smooth)Setwhethertousesmoothshadingornot.

Touselightingyouobviouslyneedtodefinelights.Twodifferentlightsexist:directionallights(likethesun),andpositionallights.Lighthaveacolor.(Weonlysupportdiffuselight,notspecularreflection.)Thefollowingfunctionsexisttodefineanduselights:

d3d_light_define_direction(ind,dx,dy,dz,col)Definesadirectedlight.indistheindexofthelight(useasmallpositivenumber).(dx,dy,dz)isthedirectionofthelight.colisthecolorofthelight(oftenyouwanttousec_white.Thisfunctiondoesnotturnthelighton.d3d_light_define_point(ind,x,y,z,range,col)Definesapointlight.indistheindexofthelightuseasmallpositivenumber).(x,y,z)isthepositionofthelight.rangeindicatestillhowfarthelightshines.Theintensityofthelightwilldecreaseoverthisrange.colisthecolorofthelight.Thisfunctiondoesnotturnthelighton.

d3d_light_enable(ind,enable)Enables(true)ordisables(false)lightnumberind.

Thewayanobjectreflectslightdependsontheanglebetweenthelightdirectionandthenormalofthesurface,thatis,thevectorpointingawayfromthesurface.Hence,tocreatelightedobjectsyouneednotonlyprovidethepositionoftheverticesbutalsotheirnormals.Forthisfouradditionalfunctionsareavaliabletodefinetheverticesofprimitives:

d3d_vertex_normal(x,y,z,nx,ny,nz)Addvertex(x,y,z)totheprimitive,withnormalvector(nx,ny,nz).d3d_vertex_normal_color(x,y,z,nx,ny,nz,col,alpha)Addvertex(x,y,z)totheprimitive,withnormalvector(nx,ny,nz),andwithitsowncolorandalphavalue.d3d_vertex_normal_texture(x,y,z,nx,ny,nz,xtex,ytex)Addvertex(x,y,z)totheprimitive,withnormalvector(nx,ny,nz),andwithposition(xtex,ytex)inthetexture,blendingwiththecolorandalphavaluesetbefore.d3d_vertex_normal_texture_color(x,y,z,nx,ny,nz,xtex,ytex,col,alpha)

Addvertex(x,y,z)totheprimitive,withnormalvector(nx,ny,nz),andwithposition(xtex,ytex)inthetexture,blendingwithitsowncolorandalphavalue.

Notethatforthebasicshapesthatyoucandrawthenormalsareautomaticallysetcorrectly.

Creatingmodels

Whenyouneedtodrawlargemodelsitisratherexpensivetocallallthedifferentdrawingfunctionsagainandagainineverystep.Toavoidthisyoucancreatemodels.Amodelconsistsofanumberofdrawingprimitivesandshapes.Onceamodeliscreatedyoucandrawitatdifferentplaceswithjustonefunctioncall.Modelscanalsobeloadedfromafileorsavedtoafile.

Beforegivingthedifferentfunctionsavailablethereisoneimportantpoint:thehandlingoftextures.Asdescribedearlier,texturearetakenfromspritesandbackgrounds.Theindicesofthetexturescanbedifferentatdifferentmoments.Asaresultmodelsdonotcontainanytextureinformation.Onlywhenyoudrawamodelyouprovidethetexture.Soyoucanonlyuseonetextureinamodel.Ifyouneedmoretexturesyoumusteithercombinetheminone(andcarefullydealwiththetexturecoordinates)oryoumustusemultiplemodels.Theadvantageofthisisthatyoucandrawthesamemodeleasilywithdifferenttextures.

Forcreating,loading,saving,anddrawingmodels,thefollowingfunctionsexist:

d3d_model_create()Createsanewmodelandreturnsitsindex.Thisindexisusedinallotherfunctionsdealingwithmodels.d3d_model_destroy(ind)Destroysthemodelwiththegivenindex,freeingitsmemory.d3d_model_clear(ind)Clearsthemodelwiththegivenindex,removingallitsprimitives.d3d_model_save(ind,fname)Savesthemodeltotheindicatedfilename.d3d_model_load(ind,fname)Loadsthemodelfromtheindicatedfilename.d3d_model_draw(ind,x,y,z,texid)Drawsthemodelatposition(x,y,z).texidisthetexturethatmustbeused.Use-1ifyoudonotwanttouseatexture.Ifyouwanttorotateorscalethemodelyoucanusethetransformationroutinesdescribedbefore.

Foreachprimitivefunctionthereisanequivalenttoaddittoamodel.Thefunctionshavethesameargumentsasbeforeexceptthateachhasafirstargumenttheindexofthemodel,andnotextureinformationisprovided.

d3d_model_primitive_begin(ind,kind)Addsa3Dprimitivetothemodeloftheindicatedkind:pr_pointlist,pr_linelist,pr_linestrip,pr_trianglelist,pr_trianglestriporpr_trianglefan.d3d_model_vertex(ind,x,y,z)Addvertex(x,y,z)tothemodel.d3d_model_vertex_color(ind,x,y,z,col,alpha)Addvertex(x,y,z)tothemodel,withitsowncolorandalphavalue.d3d_model_vertex_texture(ind,x,y,z,xtex,ytex)Addvertex(x,y,z)tothemodelwithposition(xtex,ytex)inthetexture.d3d_model_vertex_texture_color(ind,x,y,z,xtex,ytex,col,alpha)

Addvertex(x,y,z)tothemodelwithtextureandcolorvalues.d3d_model_vertex_normal(ind,x,y,z,nx,ny,nz)Addvertex(x,y,z)tothemodel,withnormalvector(nx,ny,nz).d3d_model_vertex_normal_color(ind,x,y,z,nx,ny,nz,col,alpha)Addvertex(x,y,z)tothemodel,withnormalvector(nx,ny,nz),andwithitsowncolorandalphavalue.d3d_model_vertex_normal_texture(ind,x,y,z,nx,ny,nz,xtex,ytex)

Addvertex(x,y,z)tothemodel,withnormalvector(nx,ny,nz),withtextureposition.d3d_model_vertex_normal_texture_color(ind,x,y,z,nx,ny,nz,xtex,ytex,col,alpha)

Addvertex(x,y,z)tothemodel,withnormalvector(nx,ny,nz),withtextureandcolorvalues.d3d_model_primitive_end(ind)Endthedescriptionoftheprimitiveinthemodel.

Besidesprimitivesyoucanalsoaddbasicshapestothemodels.Againthefunctionslookalmostthesamebutwithamodelindexandwithouttextureinformation:

d3d_model_block(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat)Addsablockshapetothemodel.d3d_model_cylinder(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat,closed,steps)

Addsacylindershapetothemodel.d3d_model_cone(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat,closed,steps)

Addsaconeshapetothemodel.

d3d_model_ellipsoid(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat,steps)

Addsaellipsoidshapetothemodel.d3d_model_wall(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat)Addsawallshapetothemodel.d3d_model_floor(ind,x1,y1,z1,x2,y2,z2,hrepeat,vrepeat)Addsafloorshapetothemodel.

Usingmodelscanconsiderablespeedupthegraphicsinyour3Dgamesandyoushouldusethemwheneveryoucan.

Finalwords

The3DfunctionsinGameMakercanbeusedtomakesomenice3Dgames.However,theyarelimitedinfunctionalityandstillleavequitealotofworktoyou.Don'texpectthatyoucanmakeyourownQuakewithit.GameMakerisandremainsprimarilyapackageformaking2-dimensionalgames.

Documents

Game Maker Helpavailable to control all aspects of your game. The following topics exist in this section: Language overview Computing things Game play User interaction Game graphics