EDIT: following the first answer I have looked more into stackoverflow and rephrased the problem as °how can I use only hd files?” and found this: How do I stop Cocos2D from requiring standard definition resources (SD images)? I will now try the proposed solution and if it works I will leave the edited title and remove the initial question that might be misleading.
is a while that I am trying to learn Cocos2d and using books like cookbook and learn cocos2d. Those are a great start but sometimes I get stuck into problems like the one I will try to explain today.
I started modifying the example on using CCParallaxNode in book 1 at page 66. My goal is to add four layers of the following size: 960 pixel tall and 1280 pixel widht running on an iPhone simulator with iOS 5.0 and with Cocos2d 1.01 rc library.
I did create a new project using the templates installed and modified the HelloWorldLayer.m class as following:
// Import the interfaces
#import "HelloWorldLayer.h"
// HelloWorldLayer implementation
@implementation HelloWorldLayer
+(CCScene *) scene
{
// 'scene' is an autorelease object.
CCScene *scene = [CCScene node];
// 'layer' is an autorelease object.
HelloWorldLayer *layer = [HelloWorldLayer node];
// add layer as a child to scene
[scene addChild: layer];
// return the scene
return scene;
}
// on "init" you need to initialize your instance
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init])) {
CCSprite* parallaxLayer01 = [CCSprite spriteWithFile:@"0-hd-red.png"];
CCSprite* parallaxLayer02 = [CCSprite spriteWithFile:@"0-hd-red.png"];
CCSprite* parallaxLayer03 = [CCSprite spriteWithFile:@"0-hd-red.png"];
CCSprite* parallaxLayer04 = [CCSprite spriteWithFile:@"0-hd-red.png"];
/**
CCSprite* parallaxLayer01 = [CCSprite spriteWithFile:@"0-hd.png"];
CCSprite* parallaxLayer02 = [CCSprite spriteWithFile:@"1-hd.png"];
CCSprite* parallaxLayer03 = [CCSprite spriteWithFile:@"2-hd.png"];
CCSprite* parallaxLayer04 = [CCSprite spriteWithFile:@"3-hd.png"];
**/
/**
CCSprite* parallaxLayer01 = [CCSprite spriteWithFile:@"2-hd.png"];
CCSprite* parallaxLayer02 = [CCSprite spriteWithFile:@"2-hd.png"];
CCSprite* parallaxLayer03 = [CCSprite spriteWithFile:@"2-hd.png"];
CCSprite* parallaxLayer04 = [CCSprite spriteWithFile:@"2-hd.png"];
**/
/**
CCSprite* parallaxLayer01 = [CCSprite spriteWithFile:@"bar.png"];
CCSprite* parallaxLayer02 = [CCSprite spriteWithFile:@"bar.png"];
CCSprite* parallaxLayer03 = [CCSprite spriteWithFile:@"bar.png"];
CCSprite* parallaxLayer04 = [CCSprite spriteWithFile:@"bar.png"];
**/
/**
CCSprite* parallaxLayer01 = [CCSprite spriteWithFile:@"bar-hd.png"];
CCSprite* parallaxLayer02 = [CCSprite spriteWithFile:@"bar-hd.png"];
CCSprite* parallaxLayer03 = [CCSprite spriteWithFile:@"bar-hd.png"];
CCSprite* parallaxLayer04 = [CCSprite spriteWithFile:@"bar-hd.png"];
**/
//Create a parallax node and add all four sprites
CCParallaxNode* parallaxNode = [CCParallaxNode node];
[parallaxNode setPosition:ccp(0,0)];
[parallaxNode addChild:parallaxLayer01 z:1 parallaxRatio:ccp(0, 0) positionOffset:ccp(0,0)];
[parallaxNode addChild:parallaxLayer02 z:2 parallaxRatio:ccp(1, 0) positionOffset:ccp(0,0)];
[parallaxNode addChild:parallaxLayer03 z:3 parallaxRatio:ccp(2, 0) positionOffset:ccp(0,0)];
[parallaxNode addChild:parallaxLayer04 z:4 parallaxRatio:ccp(3, 0) positionOffset:ccp(0,0)];
[self addChild:parallaxNode z:0 tag:1];
//Move the node to the left then the right
//This creates the effect that we are moving to the right then the left
CCMoveBy* moveRight = [CCMoveBy actionWithDuration:5.0f position:ccp(-80, 0)];
CCMoveBy* moveLeft = [CCMoveBy actionWithDuration:2.5f position:ccp(80, 0)];
CCSequence* sequence = [CCSequence actions:moveRight, moveLeft, nil];
CCRepeatForever* repeat = [CCRepeatForever actionWithAction:sequence];
[parallaxNode runAction:repeat];
}
return self;
}
// on "dealloc" you need to release all your retained objects
- (void) dealloc
{
// in case you have something to dealloc, do it in this method
// in this particular example nothing needs to be released.
// cocos2d will automatically release all the children (Label)
// don't forget to call "super dealloc"
[super dealloc];
}
@end
I did try to run the code using 4, a PNG image with alpha channel created using GIMP. It did work initially and now doesn’t anymore. I am not sure on what I did to mess up.
The weird thing is that the with image 5 it does work.
I have checked and there are limits on the UIImage specification that suggest to use a 1024 x 1024 image. So I did and rescaled image 6 and created image 
3 which is within the limit specified by UIImage but does not work.
For not work I mean that the code crashes with the following error message:
2012-04-19 17:14:29.189 ParallaxNodeTest[3713:10a03] cocos2d: cocos2d v1.0.1
2012-04-19 17:14:29.190 ParallaxNodeTest[3713:10a03] cocos2d: Using Director Type:CCDirectorDisplayLink
2012-04-19 17:14:29.226 ParallaxNodeTest[3713:10a03] cocos2d: OS version: 5.1 (0x05010000)
2012-04-19 17:14:29.227 ParallaxNodeTest[3713:10a03] cocos2d: GL_VENDOR: Apple Computer, Inc.
2012-04-19 17:14:29.228 ParallaxNodeTest[3713:10a03] cocos2d: GL_RENDERER: Apple Software Renderer
2012-04-19 17:14:29.229 ParallaxNodeTest[3713:10a03] cocos2d: GL_VERSION: OpenGL ES-CM 1.1 APPLE
2012-04-19 17:14:29.229 ParallaxNodeTest[3713:10a03] cocos2d: GL_MAX_TEXTURE_SIZE: 4096
2012-04-19 17:14:29.230 ParallaxNodeTest[3713:10a03] cocos2d: GL_MAX_MODELVIEW_STACK_DEPTH: 16
2012-04-19 17:14:29.231 ParallaxNodeTest[3713:10a03] cocos2d: GL_MAX_SAMPLES: 4
2012-04-19 17:14:29.233 ParallaxNodeTest[3713:10a03] cocos2d: GL supports PVRTC: YES
2012-04-19 17:14:29.234 ParallaxNodeTest[3713:10a03] cocos2d: GL supports BGRA8888 textures: YES
2012-04-19 17:14:29.235 ParallaxNodeTest[3713:10a03] cocos2d: GL supports NPOT textures: YES
2012-04-19 17:14:29.235 ParallaxNodeTest[3713:10a03] cocos2d: GL supports discard_framebuffer: YES
2012-04-19 17:14:29.235 ParallaxNodeTest[3713:10a03] cocos2d: compiled with NPOT support: NO
2012-04-19 17:14:29.236 ParallaxNodeTest[3713:10a03] cocos2d: compiled with VBO support in TextureAtlas : YES
2012-04-19 17:14:29.236 ParallaxNodeTest[3713:10a03] cocos2d: compiled with Affine Matrix transformation in CCNode : YES
2012-04-19 17:14:29.237 ParallaxNodeTest[3713:10a03] cocos2d: compiled with Profiling Support: NO
2012-04-19 17:14:29.268 ParallaxNodeTest[3713:10a03] cocos2d: surface size: 960x640
2012-04-19 17:14:29.336 ParallaxNodeTest[3713:10a03] cocos2d: Filename(0-hd-red.png) contains -hd suffix. Removing it. See cocos2d issue #1040
2012-04-19 17:14:29.337 ParallaxNodeTest[3713:10a03] cocos2d: CCFileUtils: Warning HD file not found: 0-red-hd.png
2012-04-19 17:14:29.338 ParallaxNodeTest[3713:10a03] cocos2d: CCTexture2D. Can't create Texture. UIImage is nil
2012-04-19 17:14:29.339 ParallaxNodeTest[3713:10a03] cocos2d: Couldn't add image:0-red.png in CCTextureCache
2012-04-19 17:14:29.340 ParallaxNodeTest[3713:10a03] cocos2d: Filename(0-hd-red.png) contains -hd suffix. Removing it. See cocos2d issue #1040
2012-04-19 17:14:29.340 ParallaxNodeTest[3713:10a03] cocos2d: CCFileUtils: Warning HD file not found: 0-red-hd.png
2012-04-19 17:14:29.341 ParallaxNodeTest[3713:10a03] cocos2d: CCTexture2D. Can't create Texture. UIImage is nil
2012-04-19 17:14:29.342 ParallaxNodeTest[3713:10a03] cocos2d: Couldn't add image:0-red.png in CCTextureCache
2012-04-19 17:14:29.342 ParallaxNodeTest[3713:10a03] cocos2d: Filename(0-hd-red.png) contains -hd suffix. Removing it. See cocos2d issue #1040
2012-04-19 17:14:29.343 ParallaxNodeTest[3713:10a03] cocos2d: CCFileUtils: Warning HD file not found: 0-red-hd.png
2012-04-19 17:14:29.344 ParallaxNodeTest[3713:10a03] cocos2d: CCTexture2D. Can't create Texture. UIImage is nil
2012-04-19 17:14:29.345 ParallaxNodeTest[3713:10a03] cocos2d: Couldn't add image:0-red.png in CCTextureCache
2012-04-19 17:14:29.345 ParallaxNodeTest[3713:10a03] cocos2d: Filename(0-hd-red.png) contains -hd suffix. Removing it. See cocos2d issue #1040
2012-04-19 17:14:29.346 ParallaxNodeTest[3713:10a03] cocos2d: CCFileUtils: Warning HD file not found: 0-red-hd.png
2012-04-19 17:14:29.365 ParallaxNodeTest[3713:10a03] cocos2d: CCTexture2D. Can't create Texture. UIImage is nil
2012-04-19 17:14:29.366 ParallaxNodeTest[3713:10a03] cocos2d: Couldn't add image:0-red.png in CCTextureCache
2012-04-19 17:14:29.367 ParallaxNodeTest[3713:10a03] *** Assertion failure in -[CCParallaxNode addChild:z:parallaxRatio:positionOffset:], /Users/daniele/Desktop/ParallaxNodeTest/ParallaxNodeTest/libs/cocos2d/CCParallaxNode.m:91
2012-04-19 17:14:29.369 ParallaxNodeTest[3713:10a03] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Argument must be non-nil'
*** First throw call stack:
(0x19e2022 0x1f7ccd6 0x198aa48 0x11af2cb 0x40661 0xb588e 0x3ba25 0xb5632 0xb4d3e 0x8164be 0x817274 0x826183 0x826c38 0x81a634 0x279aef5 0x19b6195 0x191aff2 0x19198da 0x1918d84 0x1918c9b 0x816c65 0x818626 0xb4816 0x24b5 0x1)
I think that the image size is not the issue here as I was previously able to run but the fact that it works with the image 5 and not with the other images 6 suggests me that is something to do with how I created the PNG files using GIMP..
Any glue? I attach the screenshot of the GIMP settings 4 I am using (not in English, will provide translation below):
Thick on:
Save colour as background, save resolution, save date of creation, save comments and save value of colors of transparents dots.
Not thicked:
Interlacment (Adam7), save gamma, save layer move
In order to use retina images, you must include both the -hd and non-hd files with your project. They don’t have to necessarily be the proper sizes, but they must both exist.
So if you want to use a file called
0-red.png, you must include0-red.pngand0-red-hd.png. Also, take note to have the-hdbe at the end of the filename.