Patent ID: 6961057

Claim:
A computer graphics system for processing image data including Z data for use in displaying three dimensional images on a display unit, comprising: a depth buffer providing for temporary storage of Z data; and a graphics processing unit having a graphics engine for generating image data including Z data, and a memory interface unit communicatively coupled to the graphics engine and communicatively coupled to the depth buffer via a depth buffer interface, the graphics processing unit being operative to compress at least a portion of the generated Z data, to write the compressed portion of Z data to the depth buffer via the depth buffer interface in a compressed format, to read portions of compressed Z data from the depth buffer via the depth buffer interface, and to decompress the compressed Z data read from the buffer; wherein the graphics engine comprises: a plurality of graphics pipeline stages for generating image data including Z data; and a Z raster operations unit communicatively coupled with the memory interface unit, the Z raster operations unit for receiving the generated Z data, and being operative to compress selected portions of the generated Z data, to receive compressed Z data from the depth buffer via the memory unit interface and the depth buffer interface, and to decompress the compressed Z data; whereby effective Z data bandwidth through the depth buffer interface is maximized in order to facilitate fast depth buffer access operations.