NGUI Atlas, Atlas Type Reference

在NGUI中，通过创建图集及引用图集，实际使用时指定引用图集而非具体图集本身，可以创建多语言，或高配低配版本资源包。

NGUI Atlas
http://www.cnblogs.com/answerwinner/p/3848074.html

UI Atlas
Atlas Type Reference

You can have one atlas simply point to another one. This
is useful if you want to be able to quickly replace the
contents of one atlas with another one, for example for
swapping an SD atlas with an HD one, or replacing an
English atlas with a Chinese one. All the sprites
referencing this atlas will update their references to the
new one.

UIAtlas mainUIAtlas = Resources.Load("Atlases/Main UI", typeof(UIAtlas)) as UIAtlas;
UIAtlas mainUIAtlasReference = Resources.Load("Atlases/Main UI Reference", typeof(UIAtlas)) as UIAtlas;
mainUIAtlasReference.replacement = mainUIAtlas;

UIAtlas Class Reference
http://www.tasharen.com/ngui/docs/class_u_i_atlas.html

NGUI: UIAtlas
http://www.tasharen.com/?page_id=120