Patent ID: 8089486

Claim:
A graphics processor, comprising: a rasterization pipeline comprising a plurality of sequentially arranged processing stages which render display pixel data from input primitive object data; a memory which stores data utilized by at least one processing stage of the plurality of sequentially arranged processing stages of the rasterization pipeline, wherein the data utilized by the at least one processing stage comprises depth values of a two-dimensional screen tile of pixels; and a pre-fetch mechanism which retrieves the data utilized by the at least one processing stage with respect to a processed pixel in advance of the processed pixel arriving at the at least one processing stage, wherein the retrieved data is stored in a cache memory of the at least one processing stage of the rasterization pipeline, wherein the at least one processing stage includes a tile test block comprising a table that stores minimum and maximum depth values of the two-dimensional screen tile of pixels, wherein the tile test block accesses the table to retrieve the minimum and maximum depth values of the two-dimensional screen tile of pixels, compares a depth value of the processed pixel with the minimum and maximum depth values of the two-dimensional screen tile of pixels, discards the processed pixel when the depth value of the processed pixel is greater than the maximum depth value of the two-dimensional screen tile of pixels, updates the cache memory with the depth value of the processed pixel when the depth value of the processed pixel is less than the minimum depth value of the two-dimensional screen tile of pixels, and enables a pixel test block to execute an individual pixel test when the depth value of the processed pixel is less than the maximum depth value of the two-dimensional screen tile of pixels and greater than the minimum depth value of the two-dimensional screen tile of pixels, and wherein the pixel test block accesses the cache memory to retrieve one or more depth values of the two-dimensional screen tile of pixels, and compares the depth value of the processed pixel with the one or more depth values retrieved from the cache memory.