cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   demetriusb
   Member

   I have a layer that I've added a particle effect to:
   My layer is set up like this:
   

   aboutLayer = [[CCLayer alloc] init]; //initialize new layer

   I have particle within the layer that's set up like this:
   

   // sun
   	CCParticleSystem *sun = [[CCParticleGalaxy alloc] initWithTotalParticles:650];
   	sun.texture = [[CCTextureCache sharedTextureCache] addImage: @"atomic.png"];
   	[aboutLayer addChild:sun];
           [aboutLayer addChild:sun <strong>tag:kTagNode</strong>];

   I want the particle within the LAYER to move so I tried something like this:
   

   (void) ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event
   {
   	CGPoint touchLocation = [touch locationInView: [touch view]];
   	CGPoint prevLocation = [touch previousLocationInView: [touch view]];	
   
   	touchLocation = [[CCDirector sharedDirector] convertToGL: touchLocation];
   	prevLocation = [[CCDirector sharedDirector] convertToGL: prevLocation];
   
   	CGPoint diff = ccpSub(touchLocation,prevLocation);
   
   	CCNode *node = [self getChildByTag:kTagNode];
   	CGPoint currentPos = [node position];
   	[node setPosition: ccpAdd(currentPos, diff)];

   I get this warning:
   

   warning: 'CCLayer' may not respond to '-addChild:tag:'

   And then the app crashes when I try to run it.

   Any help would is appreciated.

   DemetriusB

   Posted 1 year ago #
2. 

   Mark Sawicki
   Member

   demetriusb,

   What version of cocos2d-iphone are you using?

   Look at CCNode (version 0.99.4)

   /** Adds a child to the container with z-order as 0.
    It returns self, so you can chain several addChilds.
    @since v0.7.1
    */
   -(id) addChild: (CCNode*)node;
   
   /** Adds a child to the container with a z-order
    It returns self, so you can chain several addChilds.
    @since v0.7.1
    */
   -(id) addChild: (CCNode*)node z:(int)z;
   
   /** Adds a child to the container with z order and tag
    It returns self, so you can chain several addChilds.
    @since v0.7.1
    */
   -(id) addChild: (CCNode*)node z:(int)z tag:(int)tag;

   If you want to tag it, give it a z order too .

   -Mark

   Posted 1 year ago #
3. 

   demetriusb
   Member

   I'm using 993.

   I tried something like this:
   

   CCNode *node = [aboutLayer getChild:sun];

   But got:
   

   error: 'sun' undeclared (first use in this function)

   If I call CCParticleSystem *sun in the .h file then I get
   

   warning: local declaration of 'sun' hides instance variable

   I'm then not sure how to rewrite
   

   CCParticleSystem *sun = [[CCParticleGalaxy alloc] initWithTotalParticles:650];

   to make it work.

   Demetrius

   Posted 1 year ago #
4. 

   Mark Sawicki
   Member

   Demetriusb,

   You have a variable scope issue going on. Easier to answer your first post, let's work off of that.

   Did you try:
   

   [aboutLayer addChild:sun z:1 tag:kTagNode];

   and then later, when you want to do something with that node, use
   

   [aboutLayer getChildByTag:kTagNode];

   ?

   -Mark

   Posted 1 year ago #
5. 

   demetriusb
   Member

   Thanks. Your code works.

   Here's the difference:
   

   [aboutLayer addChild:sun tag:kTagNode];

   [aboutLayer addChild:sun z:1 tag:kTagNode];  //WORKS

   The z:1 is important. Without it it throws the error
   

   warning: 'CCLayer' may not respond to '-addChild:tag:'

   which makes it crash.

   CCNode *node = [self getChildByTag:kTagNode];

   CCNode *node = [aboutLayer addChild:sun z:1 tag:kTagNode];  //WORKS

   I had tried changing self to about but again without the z:1 it wouldn't work.

   Can you explain to me why z:1 is necessary.

   Thanks again for your help.

   DemetriusB

   Posted 1 year ago #
6. 

   Mark Sawicki
   Member

   Demetriusb,

   That's just the way it was defined, there is no definition for [.. addChild:tag] it's either [.. addChild:], or [.. addChild:z], or [.. addChild:z:tag].

   err. You mean, what is z-order? Z-order determines the order things are drawn on the screen, higher z-order means it will be drawn on top of something that has a lower z order.

   Mark

   Posted 1 year ago #

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