cocos2d/cocos2d-x — pull request #5118 by ricardoquesada (2014-01-18 00:10:13+00:00)
Title: Renderer uses a float as a key

Instead of using a 64-bit int key with viewport, opaque and depth,
it only uses a 32-bit float with only the depth.
Saves time in:
- No need to convert the 32-bit float into 24-bit int
- keys are shorter