COCOS2D + BOX2DCreating physics game in 1 hour

WHO IS ROD?

• Founder of Prop Group www.prop.gr

• Background in enterprise software, now iPhone+iPad games!

• 2D physics game, Payload in the AppStore

In Progress...

www.cocos2dbook.com

SNOWBALL TOSS!

WHY COCOS2D

• Games are fun! Making a game does not have to be hard.

• Write less infrastructure code, spend more time on design and core gameplay

• OpenGL ES rendering and performance without having to learn OpenGL ES to get started

• It is free!

GETTING COCOS2D

http://github.com/cocos2d/cocos2d-iphone

GETTING COCOS2D - PART 2

1. Clone the Git Repository2. Install the Templates

XCODE TEMPLATES

• New Project -> Cocos2D Templates

COCOS2D

• Objective-C framework for games

• Scene Management, Textures, Audio

• Everything but the kitchen sink (3D stuff)*

• OpenGL ES rendering and optimizations, Actions, Tile Maps, Parallax Scrolling, Scheduler, High Score service, ...

COCOS2DESSENTIALS

• Your game is divided into scenes, scenes into layers

• Layers have what you care about, the Sprites

• Director is used to switch between scenes

• Everything uses the CC namespace, so layers are CCLayers, CCScenes, CCSprites ...

LAYERS AND SCENES

CCSprite(s)

Background

CCLayer

GameplayScene

CCSceneGameplay

CCLayer

LAYERS AND TOUCHAccelerometer

GameplayScene

CCLayer

CCScene

CCLayer

CCLayer

Touch

MULTIPLE SCENES

GameplayScene

CCLayer

CCScene

CCLayer

CCLayer

Level Completed

SceneCCLayer

CCScene

CCLayer

CCLayerDirector

CCScene

COCOS2DACTIONS

• Actions are an easy way to apply transitions, effects, and animations to your sprites

• MoveTo, MoveBy, ScaleBy, ScaleTo, FadeIn, FadeOut ...CCAction *moveAction = [CCMoveBy actionWithDuration:2.0f

position:CGPointMake(50.0f,0.0f)];[playerSprite runAction:moveAction];

2 seconds

COCOS2D+BOX2DESSENTIALS 2

• Box2D is C++

• 2D rigid physics simulation engine with continuous collision detection

• All your files that touch C++ or include it must be Objective-C++ (.mm)

• Tuned for 1 meter sized objects!

• Use a fixed time step!

A GAME IN 7 STEPS

• Let’s begin

STEP 1

• Attach the director to the AppDelegate

window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];[window setUserInteractionEnabled:YES];!// cocos2d will inherit these values[window setMultipleTouchEnabled:YES]; // cocos2d will inherit these values// create an openGL view inside a window[[CCDirector sharedDirector] attachInView:window];![window makeKeyAndVisible];! !

• Director Options

STEP 2

• init()

• createPhysicsWorld

• debug draw

• ground body

INIT()-(id)init {

! if ((self=[super init])) {! ! CGSize screenSize = [CCDirector sharedDirector].winSize;! !! ! // enable touches! ! self.isTouchEnabled = YES;! ! // enable accelerometer! ! self.isAccelerometerEnabled = YES;! !! ! [self createPhysicsWorld];! !! ! [self addNewBodyWithCoords:ccp((screenSize.width/2)+80.0f, screenSize.height/2) ! ! ! ! ! withDimensions:ccp(1.0f,0.5f) ! ! ! ! ! ! andDensity:3.0f ! ! ! ! ! andWithSprite:ICE_BLOCK_FILENAME_1];! !! ! // Start the scheduler to call the tick function! ! [self schedule: @selector(tick:)];! }! return self;}

CREATEPHYSICSWORLD()// Define the gravity vector.

! b2Vec2 gravity;! gravity.Set(0.0f, -10.0f);!! // Do we want to let bodies sleep?! // This will speed up the physics simulation! bool doSleep = true;!! // Construct a world object, which will hold and simulate the rigid bodies.! world = new b2World(gravity, doSleep);!! world->SetContinuousPhysics(true); b2BodyDef groundBodyDef;! groundBodyDef.position.Set(0, 0); // bottom-left corner!! // Call the body factory which allocates memory for the ground body! // from a pool and creates the ground box shape (also from a pool).! // The body is also added to the world.! b2Body* groundBody = world->CreateBody(&groundBodyDef); b2PolygonShape groundBox;! !!! // bottom! groundBox.SetAsEdge(b2Vec2(0,0), b2Vec2(screenSize.width/PTM_RATIO,0));! groundBody->CreateFixture(&groundBox);

STEP 3

• Create the dynamic blocks

CODE+DEMOPhysics World + Dynamic Blocks

STEP 4

• Touch Events

CODE+DEMOTouch Events Demo

STEP 5

• Time to add graphics!

GRAPHICS DETAILS

• Background Layer

• Sprites for the static shapes

• Sprites for the snowballs

• Penguin animation

• Instructions Layer

STEP 6

Let it snow! - Fun with Particle Systems

STEP 7

Pump up the volume!

CLOSING THOUGHTS

• Sample Code != Production Code

• Cocos2d Website:

http://www.cocos2d-iphone.org/

Look at the sample tests included with Cocos2D!

THANK YOU

• rod@prop.gr

• twitter.com/rodstrougo

• www.prop.gr

• www.cocos2dbook.com

EXTRAS

• SpriteSheets

• Creating Physics Models

• Collision detection

• Accelerometer Filters

• Multi-touch handling

HOW-TO PHYSICS MODELS

• VertexHelper & Mekanimo

http://github.com/jfahrenkrug/VertexHelper

http://www.mekanimo.net/

• Ricardo’s LevelSVG

http://www.sapusmedia.com/levelsvg/