Package	starling.textures
Class	public class TextureAtlas
Inheritance	TextureAtlas Object

Using a texture atlas for your textures solves two problems:

• There is always one texture active at a given moment. Whenever you change the active texture, a "texture-switch" has to be executed, and that switch takes time.
• Any Stage3D texture has to have side lengths that are powers of two. Starling hides this limitation from you, but at the cost of additional graphics memory.

By using a texture atlas, you avoid both texture switches and the power-of-two limitation. All textures are within one big "super-texture", and Starling takes care that the correct part of this texture is displayed.

There are several ways to create a texture atlas. One is to use the atlas generator script that is bundled with Starling's sibling, the Sparrow framework. It was only tested in Mac OS X, though. A great multi-platform alternative is the commercial tool Texture Packer.

Whatever tool you use, Starling expects the following file format:

         <TextureAtlas imagePath='atlas.png'>
           <SubTexture name='texture_1' x='0'  y='0' width='50' height='50'/>
           <SubTexture name='texture_2' x='50' y='0' width='20' height='30'/> 
         </TextureAtlas>
      

If your images have transparent areas at their edges, you can make use of the frame property of the Texture class. Trim the texture by removing the transparent edges and specify the original texture size like this:

         <SubTexture name='trimmed' x='0' y='0' height='10' width='10'
             frameX='-10' frameY='-10' frameWidth='30' frameHeight='30'/>