Question

Following on from this question:

How should I go about animating over 200 images in iOS?

i’d like to know how to use a texture atlas in Xcode, but not with cocos2d. Too much of the project is already completed for me to port it over to cocos2d now. This will also be the only animation with this number of images.

The only tutorials out there seem to involve cocos2d or corona. I’ve downloaded Zwoptex and have packed all my sprites but, even then, i’m not sure if i should be trimming them, allowing rotation, giving them padding or even how i handle my retina images.

I’ve been looking at this link: http://mysterycoconut.com/blog/2011/01/cag1/ as recommended to me from my last question but it seems to gloss over many parts that i’m struggling with.

I’d really appreciate any help with this.

Answer 1

The texture atlas is designed to run with Cocos2D, there is a lot of dependencies with the other components. So I don’t think that’s a good choice for you.

The tutorial you posted is good otherwise. It could be most easy to use, but it gives a very good entry point. The main parts of this code are the - display and the - (void)displayLayer: methods:

The display method is call when the layer needs to its content. The animation will call (indirectly) the display method and here we call the displayLayer which will change the image to display (I hope I’ve been clear :!).

Here how you can refactor the display method if you want use a zwooptex file (or other) with non fixed size:

// Implement displayLayer: on the delegate to override how sample rectangles are calculated; remember to use currentSampleIndex, ignore sampleIndex == 0, and set the layer's bounds
- (void)display;
{
   static const CGRect sampleRects[11] = {
      { 0, 0, 38, 47 },       // run
      { 0, 47, 46, 47 },
      { 82, 0, 40, 47 },
      { 122, 0, 30, 47 },
      { 152, 0, 36, 47 },
      { 38, 0, 44, 47 },
      { 188, 0, 42, 47 },
      { 230, 0, 26, 47 },
      { 46, 47, 28, 47 },
      { 74, 47, 28, 47 },
      { 102, 47, 28, 47 },
   };

   unsigned int idx = [self currentSampleIndex];
   if (idx == 0)
      return;

   self.bounds = CGRectMake(0, 0, sampleRects[idx-1].size.width, sampleRects[idx-1].size.height);
   self.contentsRect = CGRectMake(sampleRects[idx-1].origin.x/256.0f, sampleRects[idx-1].origin.y/128.0f, sampleRects[idx-1].size.width/256.0f, sampleRects[idx-1].size.height/128.0f);
}

@end 

If you have any question, don’t hesitate. 😉