Michael Birsak and Michael Hanzl

Institute of Computer Graphics and Algorithms

Vienna University of Technology

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Outline

MotivationRelated workGame descriptionImplementationPerformanceDemoFuture WorkConclusions

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Motivation

Develop and release a 3D gameGoogle AndroidOpenGL ES

Experiment with AndroidNOT a computer graphics demo!!!

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Related Work

Many 2D games (tiles)Basically no 3D game in Spring 2009Now: Some 3D games available

Android Knight (3D Chess game)Games from OmniGSoft:

Super-G StuntSnow Rally City Stage…

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Idea

Space Taxi for Commodore 64 (1984)Space Taxi 2 (2004)Some inofficial versions

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Game Overview

3D, but discrete height levels7 levels + 7 bonus levels3 lives & powerTransport passengers in 3 minutesScoreHighscore

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Game Objects

Transporter

Passenger

Terrorist

Asteroid

Geyser Bullet

Packet

Banana

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Controlling

Devices have different input unitsAccelerometer

CalibrationHow to ascend or descend?

SliderHeight depends on the velocity

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Implementation Overview

Collision DetectionView Frustum CullingModelloader (obj)LODEffectsRandom level generationOwn models & images & soundsSettingsLocal & Online Highscore

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Online HighscoreCompete against other usersOnly one entry per userRegistration requiredSearch for your own result

Local HighscoreCompare your own resultsDelete all entries

Highscore Features

View highscore on your Android deviceDetailed overview of the highscore entriesOverview of your result after insertCorrect handling of time zonesCorrect handling of ties

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Highscore Implementation

Local HighscoreSQLite

Online HighscoreInsert / Login / Register: HTTP Post (HTTPS!)Retrieve Data: HTTP / XMLWeb-Server: PHP / MySQL

Client Server

Android device Webserver

HTTP Post

Response

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Highscore Security

Avoid SQL-InjectionsCheck and constrain the user inputPHP escape function

Password → SHA-512 HashSecure connection (HTTPS)Check the highscore

Special „password“Check constraints:s-pt:22-pt:48-pt:17-pt:10-le:1-ti:28-b-b-le:1001-pk-pp-d-d-d

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Lifecycle

Activities could be interruptedActivity not killedActivity killed

Screen orientation changeLess memorySave / restore state

Do not block the main thread!Avoid injuries!!!

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Performance Issues

GeometryRasterizerCreating objects expensiveGarbage Collector (~100 - 300ms)Object Oriented Design

Function calls: local, via interface, JNILoading and parsing ASCII files is slow

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Performance Solution

Reuse your objects → Object PoolTry to avoid garbage

Concatenated Strings / Java built-in methods!Invoke Garbage Collector manually

Decrease the number of polygons to renderUse the draw_texture extensionUse Java Object Serialization for model loadingWrite code that is fast

Reference: Chris Pruett: Writing Real Time Games For Android, Google IO 09, May 2009

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Performance

G1: 20 - 30 FPSEmulator: 10 - 20 FPS (Dual Core 2x3Ghz)Models: 18 - 508 / 372 triangles

push(1000)

pop(1000)

0 5 10 15 20 25 30

16.68

2.59

26.66

5.82

Stacks G1

Stack StStack

Time [ms]

iterate(10000)

remove(100, 1000)

add(1000)

0 20 40 60 80 100 120

21.75

101.27

17.63

16.4

107.99

21.56

34.02

Lists G1

LinkedList ArrayList StLinkedList

Time [ms]

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Demo

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Skills and Benefits

Controlling the game is not easy!Measuring distancesSpatial imaginationFind strategies very quicklyBalance between speed and scoreTrust in luckWork under stress

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Future work

Save the gameHighscore searchObjects

Planets / sunsSpaceships (enemies)

EffectsLens Flare

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Conclusions: Android

Permanent further developmentLicense: „Free“Easy to write applications, but…Great tools, examples, community, guidelinesOpenGL ES support not perfectDifferent hardware (currently ~11 smartphones)

Different display resolutionsDifferent input unitsPerformance

Emulator ǂ Real Device

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The END

Thank you for your attentionSpecial thanks to Peter Rautek & the instituteAre there any questions?