Basics cocos2d

iOS Game Development
with Cocos2D
Yaron Karasik
yaronkarasik@gmail.com @Greenwell
Thursday, June 21, 12

iOS Game Development
with Cocos2D
Part 1: Why Cocos2D?
Part 2: Cocos2D Basics
Part 3: Let’s build a Cocos2D game

Part 1:
Why Cocos2D?

Meet Cocos2D for iPhone
★ Open source iOS game development framework
★ Developed by Ricardo Quesada, acqui-hired by
Zynga (2011)
★ Stable v1.1 Based on OpenGL ES 1.1
★ Beta v2.0 Based on OpenGL ES 2.0
★ 3,500+ iOS games shipped

The Cocos2D Family
Cocos2d-Android
(Java)
Cocos2d-X
iPhone/Android (C++)
Cocos2d-Mac
(Obj-C)
Cocos2d-XNA
Windows Phone 7 (C#)
Cocos2d-HTML5
Web (Javascript)
Cocos3D
(Obj-C)

Proven Success

Great Effort-Flexibility Balance
0
100
Effort
Flexibility
Cocos2D/Sparrow
Unity/Corona
Direct OpenGL/
CoreGraphics

Cross Device, Cross Resolution

Active Ecosystem

And most importantly..
Tons of great features for games
SceneTransitionsSprite Sheets
Effects:
Lense, Ripple,Wave..
Actions:
Move, Rotate, Scale..
Integrated Physics Engines
Sound Support
Tile Map Support
Text RenderingParticle Systems
Parallax Scrolling
Shaders (v2.0)Ribbons

Part 2:
Cocos2D Basics

Basic Cocos2D Concepts
Director

Director
Scenes

Director
Scenes
Layers

Director
Scenes
Layers
Sprites

Director & Scenes
Intro Main Menu Level I Level 2 Victory
Options
High Scores
LossDirector
★ Game made up of “game screens” called Scenes
★ Each Scene can be considered a separate app
★ Director handles main window and executes Scenes

Layers
★ Each Scene contains several full screen Layers
★ Layers contain Sprites which are the game elements
★ Layers useful for Controls, Background, Labels, Menus.

Nodes
Nodes are anything that gets drawn or contains
things that get drawn (= Scene, Layer, Sprite)
Can: ★ Contain other Nodes
★ Schedule periodic callbacks
★ Execute Actions

Sprites in Action
Create
CCSpriteFrame* spriteFrame = [[CCSpriteFrameCache sharedSpriteFrameCache]
spriteFrameByName:@"sprite.png"];
CCSprite* sprite = [CCSprite spriteWithSpriteFrame:spriteFrame];

Sprites in Action
Add to Layer
sprite.position = ccp(x, y);
[layer addChild:sprite z:5 tag:666];
(0,0)
winSize.height
winSize.width
(x,y) at anchor point

Sprites in Action
Move
CCMoveTo *moveToAction = [CCMoveTo actionWithDuration:duration
position:newPosition];
[sprite runAction:moveToAction];
Properties can be transformed directly or through actions

Sprites in Action
Scale/Rotate
CCScaleTo *scaleToAction = [CCScaleTo actionWithDuration:duration scale:scale];
CCRotateBy *rotateByAction = [CCRotateBy actionWithDuration:duration angle:angle];
CCSequence *sequence = [CCSequence actions:scaleToAction, rotateByAction, nil];
[sprite runAction:sequence];

Sprites in Action
Animate
CCAnimation* animation = [[CCAnimationCache sharedAnimationCache]
animationByName:@"animation"];
CCAnimate* animateAction = [CCAnimate actionWithAnimation:animation];
[sprite runAction:animateAction];

Sprites in Action
Schedule Updates
[scene schedule:@selector(updateSprite:) interval:interval];

Actions
Can be performed on Sprites or any Node
Basic Move, Scale, Rotate, Bezier, Hide, Fade,Tint..
Composition Sequence, Repeat, Spawn, RepeatForever..
Ease Ease, EaseExponential, EaseBounce..
Effects Lens, Liquid, Ripple, Shaky,Twirl,Waves..
Special CallFunc, Follow..

Spritesheets
★ Added as a child to the layer
★ Created withTexturePacker or Zwoptex
★ Memory considerations, 16bit images, .pvr.ccz

Controls
★ Implement directly based on CCStandardTouchDelegate
★ Can use UIGestureRecognizer classes
★ Open source implementations of joypad/buttons available
- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;

Let’s Make a Game!
Part 3:

Let’s Make a Game!
..but ﬁrst we need a story, graphics, music and sfx :)
Part 3:

Because he likes to kill paratroopers
Para-Shoot

Graphics
Benjamin Radchek Sprites by The_Protoganist and _Allen_
http://www.freewebs.com/teh_pro/sprites.htm

Music & SFX
Explosive Attack by McTricky @ Sakari Inﬁnity
http://www.sakari-inﬁnity.net/author/McTricky
Background music, shoot sound, death sound

Sneak Peek

Steps for making Para-Shoot
Application Setup
Step 1: Adding Background
Step 2: Adding Our Hero
Step 3: Adding Bad Guys (Game Logic)
Step 4: Killing Bad Guys (Adding UI)
Step 5: Check for Bad Guy Death
Step 6: Animating Our Hero
Step 7: Animating Bad Guys Dying
Step 8: Adding Body Count
Step 9: Adding Sound & Music

New Cocos2D Project

@interface HelloWorldLayer : CCLayer
{
! // Player sprite
! CCSprite *_player;
// Target and bullet sprite arrays
! NSMutableArray *_targets;
NSMutableArray *_bullets;
! // Body count counter and isShooting flag
int _bodyCount;
BOOL _isShooting;
!
! // For body count label
! CCLabelTTF *_labelTitle;
! CCLabelTTF *_labelCount;
}
HelloWorldScene.h

HelloWorldScene.m
// Create the new scene including this layer
+(id) scene
{
! // Create the scene
! CCScene *scene = [CCScene node];
!
! // Create the layer
! HelloWorldLayer *layer = [HelloWorldLayer node];
!
! // add layer as a child to scene
! [scene addChild: layer];
!
! // return the scene
! return scene;
}

Hello World

Step 1:Adding Background
(In init)
// Get the window size to place elements
CGSize winSize = [[CCDirector sharedDirector] winSize];
// Add the background image
CCSprite *background = [CCSprite spriteWithFile:@"background.png"];
background.position = ccp(winSize.width/2, winSize.height/2);
[self addChild:background z:0];

Step 1:Adding Background

Step 2:Adding Our Hero
(In init)
// Load the sprite sheet
CCSpriteBatchNode *batchNode = [CCSpriteBatchNode
batchNodeWithFile:@"parashoot.pvr.ccz"];
[self addChild:batchNode];
// Load the sprites into the shareSpriteFrameCache
[[CCSpriteFrameCache sharedSpriteFrameCache]
addSpriteFramesWithFile:@"parashoot.plist"];
Preload the spritesheet

// Add the player sprite
CCSpriteFrame* playerFrame = [[CCSpriteFrameCache sharedSpriteFrameCache]
spriteFrameByName:@"player_01.png"];
_player = [CCSprite spriteWithSpriteFrame:playerFrame];
_player.position = ccp(_player.contentSize.width/2 + 10, winSize.height/2);
[self addChild:_player z:1];
Add the hero sprite

Step 3:Adding Bad Guys (Game Logic)
(in init)
[self schedule:@selector(addTarget:) interval:1.0f];
Schedule a new target every second

// Create a new enemy
-(void)addTarget:(ccTime)dt {
// Create the target sprite
CCSpriteFrame *targetFrame = [[CCSpriteFrameCache sharedSpriteFrameCache]
spriteFrameByName:@"target.png"];
!CCSprite *target = [CCSprite spriteWithSpriteFrame:targetFrame];
// Add the target to the layer and the array
! [self addChild:target];
! [_targets addObject:target];
Create a sprite for the target

! // Determine where to spawn the target along the X axis
! CGSize winSize = [[CCDirector sharedDirector] winSize];
// Find a random X for the target in the right half of the screen
! int minX = winSize.width/2;
! int maxX = winSize.width - target.contentSize.width;
! int rangeX = maxX - minX;
! int actualX = (arc4random() % rangeX) + minX;
target.position = ccp(actualX, 320);
target.anchorPoint = ccp(0, 0);
! // Determine speed of the target
! int minDuration = 2.0;
! int maxDuration = 4.0;
! int rangeDuration = maxDuration - minDuration;
! int actualDuration = (arc4random() % rangeDuration) + minDuration;
Generate a random x position for the target

// Create and run the actions
CCMoveTo* moveTarget = [CCMoveTo actionWithDuration:actualDuration
! ! ! position:ccp(actualX, -target.contentSize.height/2)];
CCCallFuncN* actionForTargetMoveDidFinish = [CCCallFuncN
actionWithTarget:self selector:@selector(targetMoveFinished:)];
[target runAction:[CCSequence actions:moveTarget, actionForTargetMoveDidFinish, nil]];
Create a move action for the target with a
callback when reaching the bottom

// Method for removing a target that has died or reached the
bottom
-(void)targetMoveFinished:(id)sender {
! CCSprite *target = (CCSprite *)sender;
[self removeChild:target cleanup:YES];
! [_targets removeObject:target];
}
Add the callback method for a target that
dies or reaches the bottom

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
! // Choose one of the touches to work with
! UITouch *touch = [touches anyObject];
! CGPoint location = [touch locationInView:[touch view]];
! location = [[CCDirector sharedDirector] convertToGL:location];
!
if (!_isShooting) {
_isShooting = YES;
Detect the touch

// Create the bullet
CCSpriteFrame* bulletFrame = [[CCSpriteFrameCache sharedSpriteFrameCache]
spriteFrameByName:@"bullet.png"];
CCSprite* bulletSprite = [CCSprite spriteWithSpriteFrame:bulletFrame];
bulletSprite.position = _player.position;
// Bullet actions
CCCallFuncN* actionForRemoveBullet = [CCCallFuncN actionWithTarget:self
selector:@selector(removeBullet:)];
CCMoveBy* bulletMoveBy = [CCMoveBy actionWithDuration:1.0f
position:ccp(winSize.width, 0)];
[bulletSprite runAction:[CCSequence actionOne:bulletMoveBy
two:actionForRemoveBullet]];
// Add bullet to layer and array
[self addChild:bulletSprite];
[_bullets addObject:bulletSprite];
Create the bullet

-(void)update:(ccTime)dt {
CCSprite* bulletToRemove = nil;
for (CCSprite *bullet in _bullets) {
for (CCSprite* target in _targets) {
CGRect targetBox = CGRectMake(target.position.x, target.position.y,
[target boundingBox].size.width, [target boundingBox].size.height);
// Check if bullet is in the target's bounding box
if (CGRectContainsPoint(targetBox, bullet.position)) {
// Animate target death and remove target
bulletToRemove = bullet;
}
}
}
// Remove bullet if target was hit
if (bulletToRemove != nil) {
[self removeChild:bulletToRemove cleanup:YES];
[_bullets removeObject:bulletToRemove];
}
}

Step 6:Animating Our Hero
(In init)
// Load the animation for player
NSMutableArray *animFrames1 = [NSMutableArray array];
for (int i = 1; i < 12; i++) {
CCSpriteFrame *frame = [[CCSpriteFrameCache sharedSpriteFrameCache] spriteFrameByName:
[NSString stringWithFormat:@"player_%02d.png",i]];
! [animFrames1 addObject:frame];
}
[[CCAnimationCache sharedAnimationCache] addAnimation:[CCAnimation
animationWithFrames:animFrames1 delay:FRAME_DELAY] name:@"player"];!
Preload the animation from the spritesheet

(In ccTouchesEnded)
// Actions for shooting animation
CCCallFunc* actionForShootDidEnd = [CCCallFunc actionWithTarget:self
selector:@selector(shootDidEnd)];
CCAnimation* playerShootAnimation = [[CCAnimationCache sharedAnimationCache]
animationByName:@"player"];
CCAnimate* shootAnimate = [CCAnimate actionWithAnimation:playerShootAnimation];
[_player runAction:[CCSequence actionOne:shootAnimate two:actionForShootDidEnd]];
Animate the hero when shooting

Step 7:Animating Bad Guys Dying
(in update)
// Set up actions for animation and target removal
CCCallFuncN* actionForDeathDidFinish = [CCCallFuncN actionWithTarget:self
selector:@selector(targetMoveFinished:)];
CCAnimate* deathAnimation = [CCAnimate actionWithAnimation:[[CCAnimationCache
sharedAnimationCache] animationByName:@"death"] restoreOriginalFrame:NO];
[target runAction:[CCSequence actionOne:deathAnimation two:actionForDeathDidFinish]];

Step 7:Animating Bad Guys Dying

Step 8:Adding Body Count
(In init)
NSString* bodyCountString = [NSString stringWithFormat:@"%d", _bodyCount];
_labelCount = [CCLabelTTF labelWithString:bodyCountString fontName:@"Arial"
fontSize:16];
_labelCount.color = ccc3(0,0,0);
_labelCount.position = ccp(110, winSize.height - 16);
[self addChild:_labelCount z:2];
(In ccTouchesEnded)
_bodyCount++;
NSString* bodyCountString = [NSString stringWithFormat:@"%d", _bodyCount];!
[_labelCount setString:bodyCountString];

Step 8:Adding Body Count

Step 9:Adding Sound & Music
(In init)
! // Start background music, set lower volume
! SimpleAudioEngine.sharedEngine.backgroundMusicVolume = 0.4f;
! [[SimpleAudioEngine sharedEngine] playBackgroundMusic:@"explosive_attack.mp3"];
(In ccTouchesEnded)
! // Play sound effect on every shot and on death
! [[SimpleAudioEngine sharedEngine] playEffect:@"shot.wav"];
! [[SimpleAudioEngine sharedEngine] playEffect:@"death.wav"];

Step 9:Adding Sound & Music

Let’s Play!

Para-Shoot 2.0
Enemies can move and attack
Joypad + HUD
Move our hero
Different weapons, power ups and health
Game menu and high scores
Levels
Save/Load Game
Refactor code (More scenes and layers)

Refactoring Para-Shoot
Intro Main Menu Level X Victory
Options
High Score
Loss
Level X Background Player Bad Guys Joypad/HUD
Scenes:
Layers:

More stuff to explore
★ Physics Engines - Chipmunk and Box2D
★ Particle System
★ Tilemaps
★ Menu Interface

Where can you learn more
Cocos2D Demo Library (Comes with Cocos)
Wiki: http://cocos2d-iphone.org/wiki
Ray Wenderlich: http://www.raywenderlich.com
Steffen Itterheim: http://learn-cocos2d.com
SapusTongue Source Code: http://www.sapusmedia.com/sources

ThankYou!
Yaron Karasik
yaronkarasik@gmail.com
@Greenwell

Basics cocos2d

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