Game Factory – Visual Domain Specific Language

Game Factory - Visual Domain Specfic Language

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Game Factory – Visual Domain Specific Language

Pham Hai NamSCE GameLab


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Outline

• Game Factory design• C2 application requirements• Visual Domain-Specific Language• C2 template• Open-source software overview


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Game Factory

• Game Factory is a game engine with a different approach

• For game designer without knowledge about the implementation details

• Declare the game using a visual DSL• Optimization by writing extra code• Support a template for each genre of game


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Outline

• Game Factory design• C2 application requirements• Visual Domain Specific Language• C2 template• Open-source software overview


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C2 application requirements

• Divide to independent aspects– Visual display property– Game entities and relationships– Game level design– Input methods of playable characters– AI for NPCs


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C2 visual display (1)

Main section:-First person view-Third person view-Bird’s eye view

Map / Radar- Teammates position- Obstacles

GUI- Display info: textual & visual- Get info: button, slider


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C2 visual display (2)Night vision view mode-> to see in dark area-> work better with HDR color

Thermal vision view mode-> to indentify camouflaged threats-> must explicitly declare thermal material


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C2 Entities & Relationships

Entities• Human• Vehicle

– Tank– Helicopter

• Weapon– Rifle– Rocket launcher

• Bullet– Straight flying (rifle bullet)– Lock-on (missile)– Gravitational trajectory (grenade)

• Building– High Wall, Low Wall– Vertical Stair, Door

Relationships• 1 Human vs 1 Weapon

– Pick up / Drop / Select– Reload

• 1 Human vs 1 Wall– Jump over / Jump and grab– Take cover

• N Human vs 1 Human– Protect– Approach

• Weapon vs Rocket vs Vehicle– Destroy on hit– Lock the rocket on the vehicle


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Outline



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The Visual DSL (1)

• Looks like an Entity Relationship Diagram• Game designer will not directly draw the

diagram• The diagram is generated from a step by step

declaration process– At each step, there are predefined options to

choose from• The textual DSL will be generated and

compiled to make the final Lua game script


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The Visual DSL (2)


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Lua script

• Proven, Fast– Unified syntax, only one kind of data structure– Compiled language– The most popular script language in real-time game

• Extensible semantics– Can support object-oriented programming– Can support functional programming– Can support aspect-oriented programming

• Easily integrated with C++


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The Textual DSL (1)

• Is Lua script• Is supported by the a game genre template• Is generated from the Visual DSL, or written

directly by programmer• Will be run once to generate another set of

Lua scripts which describes the game logic• The generated Lua scripts is one layer on top

of C++ functions of the genre template


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The Textual DSL (2)

• Customize and extend an existing classCustomize{

Name = 'Soldier',IsSelectable = trueCommands = {Move,Attack}Model = ‘mysoldier.dae’

}

Define{Name = 'Commander',Extend = 'Soldier',Constructor = [[

Commands.Add 'IssuedProtectCommand']]

}


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The Textual DSL (3)

Relationship{Name = 'TakeCover',Actor = {'Soldier', 'Wall'},Check = [[

Require(IsNear(soldier, wall))]],Input = KeyDown('ctrl'),Perform = [[

soldier:Lean(wall)]]

}

Relationship declaration• Check will return a boolean

value• The variable is generated

automatically• Require will make Check

return another value for complexity

• Check, Input and Peform will be weaved to the correct position in an one-time compilation


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The Textual DSL (4)

• 3-tier relationship and Relationship{

Name = 'Protect',Actor = {'Soldier','Soldier','Human'},Association = {1,Many,1},Role = {'commander','soldiers','hostage'},Input = commander::IssuedProctectCommand,Check = [[

Require(Soldier.IsSelected(soldiers))Require(MouseLeftClick(hostage))

]]Perform = [[

AI.Protect(soldiers,hostage,Soldier.Subset('enemy'))]]Broken = [[ Require(hostage:IsDead) ]]Terminate = [[ soldiers:Ready() ]]

}

• Specify association• Assign role if there is

ambiguity• Method is generated for

collection• Broken condition and

terminate action


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Outline



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C2 template

• Includes a Reflective API specifically for C2 game

• Includes a media library for C2 game


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Data flow in one frame

• Get input information• Check all relationship conditions• Check all performing relationships breaking

condition• Execute performing relationship (in coroutines)• Perform queued AI requests & physics

simulation• Render the scene


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The Reflective API

• Aspect-oriented programming style– Declaration code can be organized in any way– Generated code will be put in optimized position

• Optimization:– Remove unnecessary branching statements– Follow naming convention for generated classes and

variables– Only used entities and relationships will generate code

• Support macros for readability & concise syntax


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Outline



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Nvidia PhysX for physic simulation

• Free for commercial use, closed source• Is the proven & the fastest engine• Has hardware accelerated on dedicated card. Hardware

acceleration will soon be available on Nvidia graphics card• Support Continuous Collision Detection for fast moving

object• Support Vehicle simulation• Support Broadphase Collision Detection for a large number

of moving object• Support Constraints for rag-doll simulation• Support Force Field to simulate Explosion


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Irrlicht engine for rendering

• Free for commercial use, open source• Modular, extensible

– Possible to implement advanced rendering techniques for C2 game: HDR, Instancing

– Possible to implement scene rendering technique• Cross-platform• Can be easily integrated with PhysX• Huge library of shaders and scene rendering techniques

(including indoor and outdoor rendering)• Support large amount of 3d geometry formats, including

COLLADA• Support Particle system & GUI


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RakNet for networking

• Cheap for commercial use, open source• Game specific engine• Support Lobby system with player matching• Support Peer to Peer network• Support voice communication


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Problems

• Describing the radar• Close quarter combat moves• Soldier movement on uneven surface


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Thank you

• Q & A

Documents

Game Factory – Visual Domain Specific Language