Method and system for sort independent alpha blending of graphic fragments

摘要

The method provides for sort independent alpha blending of fragments of a graphic image. A sequence of fragments has opaque fragments and transparent fragments. The opaque fragments are rendered to a frame buffer having at least a z buffer, the z buffer having stored therein z values of front most opaque fragments. Transparent fragments are stored in a list in a transparent fragment buffer. The transparent fragments are sequentially read from the list and are discarded if they are occluded by an opaque fragment. When not occluded, the transparent fragments are stored in a list. The z buffer is cleared and the transparent fragments are read sequentially from the list. Z values are stored in the z buffer for back most transparent fragments. The transparent fragments are again sequentially read from the list. Z values of currently read transparent fragments are compared to z values in the z buffer of corresponding fragments. If a currently read transparent fragment is a back most transparent fragment, then it is rendered with alpha blending to the frame buffer, otherwise it is again stored in the list. This process is repeated beginning with the clearing of the z buffer until the list is empty.