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.