Implementing order-independent transparency using front-to-back peeling

When we have to render translucent geometry, for example, a glass window in a graphics application, care has to be taken to make sure that the geometry is properly rendered in the depth order such that the opaque objects in the scene are rendered first and the transparent objects are rendered last. This unfortunately incurs additional overhead where the CPU is busy sorting objects. In addition, the blending result will be correct only from a specific viewing direction, as shown in the following figure. Note that the image on the left is the result if we view from the direction of the Z axis. There is no blending at all in the left image. If the same scene is viewed from the opposite side, we can see the correct alpha blending result.

Depth peeling (also called front-to-back peeling) is one technique that helps in this process. In this technique, the scene is rendered in slices in such a way that slices are rendered one...