使用cocos2d和box2d制作一个简单的弹射游戏 第一部分

// delete this line!
self.isAccelerometerEnabled = YES;

// Delete these lines!
CCSpriteBatchNode *batch = [CCSpriteBatchNode batchNodeWithFile:@"blocks.png" capacity:150];
[self addChild:batch z:0 tag:kTagBatchNode];

[self addNewSpriteWithCoords:ccp(screenSize.width/2, screenSize.height/2)];

CCLabelTTF *label = [CCLabelTTF labelWithString:@"Tap screen" fontName:@"Marker Felt" fontSize:32];
[self addChild:label z:0];
[label setColor:ccc3(0,0,255)];
label.position = ccp( screenSize.width/2, screenSize.height-50);

CCSprite *sprite = [CCSprite spriteWithFile:@"bg.png"];
sprite.anchorPoint = CGPointZero;
[self addChild:sprite z:-1];

sprite = [CCSprite spriteWithFile:@"catapult_base_2.png"];
sprite.anchorPoint = CGPointZero;
sprite.position = CGPointMake(181.0f, FLOOR_HEIGHT);
[self addChild:sprite z:0];

sprite = [CCSprite spriteWithFile:@"squirrel_1.png"];
sprite.anchorPoint = CGPointZero;
sprite.position = CGPointMake(11.0f, FLOOR_HEIGHT);
[self addChild:sprite z:0];

sprite = [CCSprite spriteWithFile:@"catapult_base_1.png"];
sprite.anchorPoint = CGPointZero;
sprite.position = CGPointMake(181.0f, FLOOR_HEIGHT);
[self addChild:sprite z:9];

sprite = [CCSprite spriteWithFile:@"squirrel_2.png"];
sprite.anchorPoint = CGPointZero;
sprite.position = CGPointMake(240.0f, FLOOR_HEIGHT);
[self addChild:sprite z:9];

sprite = [CCSprite spriteWithFile:@"fg.png"];
sprite.anchorPoint = CGPointZero;
[self addChild:sprite z:10];

#define FLOOR_HEIGHT    62.0f

b2Fixture *armFixture;
b2Body *armBody;

// Create the catapult's arm
//
CCSprite *arm = [CCSprite spriteWithFile:@"catapult_arm.png"];
[self addChild:arm z:1];

b2BodyDef armBodyDef;
armBodyDef.type = b2_dynamicBody;
armBodyDef.linearDamping = 1;
armBodyDef.angularDamping = 1;
armBodyDef.position.Set(230.0f/PTM_RATIO,(FLOOR_HEIGHT+91.0f)/PTM_RATIO);
armBodyDef.userData = arm;
armBody = world->CreateBody(&armBodyDef);

b2PolygonShape armBox;
b2FixtureDef armBoxDef;
armBoxDef.shape = &armBox;
armBoxDef.density = 0.3F;
armBox.SetAsBox(11.0f/PTM_RATIO, 91.0f/PTM_RATIO);
armFixture = armBody->CreateFixture(&armBoxDef);

b2RevoluteJoint *armJoint;

// Create a joint to fix the catapult to the floor.
//
b2RevoluteJointDef armJointDef;
armJointDef.Initialize(groundBody, armBody, b2Vec2(233.0f/PTM_RATIO, FLOOR_HEIGHT/PTM_RATIO));
armJointDef.enableMotor = true;
armJointDef.enableLimit = true;
armJointDef.motorSpeed  = -1260;
armJointDef.lowerAngle  = CC_DEGREES_TO_RADIANS(9);
armJointDef.upperAngle  = CC_DEGREES_TO_RADIANS(75);
armJointDef.maxMotorTorque = 4800;

armJoint = (b2RevoluteJoint*)world->CreateJoint(&armJointDef);

b2MouseJoint *mouseJoint;

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (mouseJoint != nil) return;

UITouch *myTouch = [touches anyObject];
CGPoint location = [myTouch locationInView:[myTouch view]];
location = [[CCDirector sharedDirector] convertToGL:location];
b2Vec2 locationWorld = b2Vec2(location.x/PTM_RATIO, location.y/PTM_RATIO);

if (locationWorld.x < armBody->GetWorldCenter().x + 50.0/PTM_RATIO)
{
b2MouseJointDef md;
md.bodyA = groundBody;
md.bodyB = armBody;
md.target = locationWorld;
md.maxForce = 2000;

mouseJoint = (b2MouseJoint *)world->CreateJoint(&md);
}
}

- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if (mouseJoint == nil) return;

UITouch *myTouch = [touches anyObject];
CGPoint location = [myTouch locationInView:[myTouch view]];
location = [[CCDirector sharedDirector] convertToGL:location];
b2Vec2 locationWorld = b2Vec2(location.x/PTM_RATIO, location.y/PTM_RATIO);

mouseJoint->SetTarget(locationWorld);
}

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if (mouseJoint != nil)
{
world->DestroyJoint(mouseJoint);
mouseJoint = nil;
}
}

armJointDef.motorSpeed  = -10; //-1260;

NSMutableArray *bullets;
int currentBullet;

[bullets release];

- (void)createBullets:(int)count
{
currentBullet = 0;
CGFloat pos = 62.0f;

if (count > 0)
{
// delta is the spacing between corns
// 62 is the position o the screen where we want the corns to start appearing
// 165 is the position on the screen where we want the corns to stop appearing
// 30 is the size of the corn
CGFloat delta = (count > 1)?((165.0f - 62.0f - 30.0f) / (count - 1)):0.0f;

bullets = [[NSMutableArray alloc] initWithCapacity:count];
for (int i=0; i<count; i++, pos+=delta)
{
// Create the bullet
//
CCSprite *sprite = [CCSprite spriteWithFile:@"acorn.png"];
[self addChild:sprite z:1];

b2BodyDef bulletBodyDef;
bulletBodyDef.type = b2_dynamicBody;
bulletBodyDef.bullet = true;
bulletBodyDef.position.Set(pos/PTM_RATIO,(FLOOR_HEIGHT+15.0f)/PTM_RATIO);
bulletBodyDef.userData = sprite;
b2Body *bullet = world->CreateBody(&bulletBodyDef);
bullet->SetActive(false);

b2CircleShape circle;
circle.m_radius = 15.0/PTM_RATIO;

b2FixtureDef ballShapeDef;
ballShapeDef.shape = &circle;
ballShapeDef.density = 0.8f;
ballShapeDef.restitution = 0.2f;
ballShapeDef.friction = 0.99f;
bullet->CreateFixture(&ballShapeDef);

[bullets addObject:[NSValue valueWithPointer:bullet]];
}
}
}

b2Body *bulletBody;
b2WeldJoint *bulletJoint;

- (BOOL)attachBullet
{
if (currentBullet < [bullets count])
{
bulletBody = (b2Body*)[[bullets objectAtIndex:currentBullet++] pointerValue];
bulletBody->SetTransform(b2Vec2(230.0f/PTM_RATIO, (155.0f+FLOOR_HEIGHT)/PTM_RATIO), 0.0f);
bulletBody->SetActive(true);

b2WeldJointDef weldJointDef;
weldJointDef.Initialize(bulletBody, armBody, b2Vec2(230.0f/PTM_RATIO,(155.0f+FLOOR_HEIGHT)/PTM_RATIO));
weldJointDef.collideConnected = false;

bulletJoint = (b2WeldJoint*)world->CreateJoint(&weldJointDef);
return YES;
}

return NO;
}

- (void)resetGame
{
[self createBullets:4];
[self attachBullet];
}

[self resetGame];

[self performSelector:@selector(resetGame) withObject:nil afterDelay:0.5f];

BOOL releasingArm;

if (armJoint->GetJointAngle() >= CC_DEGREES_TO_RADIANS(20))
{
releasingArm = YES;
}

// Arm is being released.
if (releasingArm && bulletJoint)
{
// Check if the arm reached the end so we can return the limits
if (armJoint->GetJointAngle() <= CC_DEGREES_TO_RADIANS(10))
{
releasingArm = NO;

// Destroy joint so the bullet will be free
world->DestroyJoint(bulletJoint);
bulletJoint = nil;

}
}

armJointDef.maxMotorTorque = 700; //4800;

// Bullet is moving.
if (bulletBody && bulletJoint == nil)
{
b2Vec2 position = bulletBody->GetPosition();
CGPoint myPosition = self.position;
CGSize screenSize = [CCDirector sharedDirector].winSize;

// Move the camera.
if (position.x > screenSize.width / 2.0f / PTM_RATIO)
{
myPosition.x = -MIN(screenSize.width * 2.0f - screenSize.width, position.x * PTM_RATIO - screenSize.width / 2.0f);
self.position = myPosition;
}
}