Patent ID: 6407741
Filing Date: 2002-06-18
Classification: G06T

Abstract:
A method for controlling compressed Z information, comprising:receiving coordinates corresponding to a pixel block of a frame, wherein the frame includes a plurality of pixel blocks, wherein each pixel block of the plurality of pixel blocks includes Z information for a plurality of pixels, wherein Z information for each pixel represents spatial depth of the pixel; determining if Z information for the pixel block is present in a cache; when the Z information for the pixel block is not present in the cache: reading a Z mask value for the pixel block; fetching the Z information for the pixel block from a Z buffer, wherein the Z mask value for the pixel block indicates a level of compression of the Z information for the pixel block in the Z buffer, wherein the Z information for the pixel block includes a primary Z value for each pixel in the pixel block, a secondary Z value for each pixel of the pixel block for which the primary Z value does not provide adequate Z coverage, a pixel mask that indicates sample coverage for each pixel of the pixel block, and a secondary mask indicating which pixels within the pixel block have secondary Z values; when the Z mask value indicates the Z information for the pixel block is compressed, decompressing the Z information; and storing the Z information for the pixel block in the cache.