Using Texture Atlases

To reduce draw calls, you can add individual textures to a texture atlas and then add one or more texture atlases to a UI canvas.

Characteristics

UI canvases and texture atlases have the following characteristics:

• Each UI canvas contains a list of texture atlases to be loaded.
• Texture atlases are loaded when the UI canvas loads. They’re unloaded when the UI canvas unloads.
• If multiple UI canvases load the same texture atlas, the texture atlas is loaded only once.
• UI elements that render textures preferentially use textures from a loaded texture atlas, if available.
• The texture atlas is only unloaded when all UI canvases that loaded it are unloaded.

Advantages

The principle advantages of texture atlases are the following:

• Draw calls are significantly reduced.
• Enhanced compression. Although source textures whose dimensions aren’t multiples of four aren’t compressed, texture atlases are always compressed.
• Forced preloading of texture groups. When the canvas loads, it also loads its texture atlases.