Patent ID: 9019271
Filing Date: 2015-04-28
Classification: G06T

Abstract:
1. A Z-culling method adapted for a three-dimensional (3D) graphics processing apparatus, the Z-culling method comprising: providing a Z cache memory to buffer a cover mask and a dynamic maximum depth value corresponding to one of a plurality of tiles of a rasterized screen, wherein the cover mask represents a pixel location of a known part in said one of the plurality of tiles, and the dynamic maximum depth value is the maximum depth value of all pixels in the known part corresponding to a view point; obtaining a draw mask, a draw maximum depth value, and a draw minimum depth value calculated according to said one of the plurality of tiles and a drawn part, wherein the drawn part are pixels of a plane constructing a 3D graphics projected on said one of the plurality of tiles, the draw mask represents the pixel location of the drawn part in said one of the plurality of tiles, the draw minimum depth value is a minimum depth value of all pixels in the drawn part corresponding to the view point, and the draw maximum depth value is a maximum depth value of all pixels in the drawn part corresponding to the view point; judging whether the pixel location of the drawn part is completely included in the pixel location of the known part, and coordinating with a comparison of the draw minimum depth value and the dynamic maximum depth value, so as to determine whether to discard the drawn part and whether to update the cover mask and the dynamic maximum depth value in the Z cache memory; maintaining the dynamic maximum depth value when the pixel location of the drawn part is completely included in the pixel location of the known part and the pixel location of the drawn part does not equal to the pixel location of the known part, and the draw minimum depth value is not greater than the dynamic maximum depth value; and updating the dynamic maximum depth value to a smaller value between the draw maximum depth value and the dynamic maximum depth value, when the pixel location of the drawn part is equal to the pixel location of the known part and the draw minimum depth value is not greater than the dynamic maximum depth value, wherein the cover mask and the dynamic maximum depth value corresponding to said one of the tiles are obtained from a system memory and then buffered in the Z cache memory.