US 6,982,713 B2
System and method for clearing depth and color buffers in a real-time graphics rendering system
Pingping Shao, Sunnyvale, Calif. (US); Jianbo Zhang, Sunnyvale, Calif. (US); Guofang Jiao, Sunnyvale, Calif. (US); Chun Yu, Sunnyvale, Calif. (US); Linglan Zhang, Sunnyvale, Calif. (US); and Jinshan Zheng, Shanghai (China)
Assigned to XGI Technology Inc., Hsinchu (Taiwan)
Filed on Jan. 13, 2003, as Appl. No. 10/341,842.
Prior Publication US 2004/0135781 A1, Jul. 15, 2004
Int. Cl. G06T 15/40 (2006.01)
U.S. Cl. 345—422 17 Claims
OG exemplary drawing
 
1. A system for clearing a depth buffer for storing depth values for pixels in a three dimensional graphics rendering system, comprising:
a first portion for adding a first frame flag to a depth value for a pixel, the first frame flag identifying a current frame;
a second portion for receiving a previous depth value for the pixel, comparing a frame flag of the previous depth value to the first frame flag, and replacing the previous depth value with an initial depth value if the frame flag is different from the current frame flag, the initial depth value having a frame flag equal to the first frame flag; and
a third portion for clearing a color buffer, the third portion being adapted to check the frame flags of a plurality of pixels in a first area, and to assign an initial color to any of the plurality of pixels having a frame flag that is different from the current frame flag, wherein the third portion is adapted to assign an initial depth value to any of the plurality of pixels having a frame flag that is different from the current frame flag and adapted to mask any of the plurality of pixels in the first area which have a frame flag that is the same as the current frame flag.