Patent ID: 7064752

Claim:
A multi-function unit of a graphics system, comprising: a hierarchical tiler configured to occlusion test primitives, the primitives comprising a maximum Z value and a minimum Z value, the maximum and minimum Z values associated with respective X-Y coordinate values, the hierarchical tiler further configured to create a Z pyramid data structure as polygons defined by a plurality of primitives are processed by the multi-function unit; a parameter interpolator coupled to the hierarchical tiler configured to receive the X-Y coordinate values from the hierarchical tiler and generate a Z value at the pixel level for each received X-Y coordinate value; a pixel-level comparator coupled to the parameter interpolator configured to determine at a pixel level which values need to be written by a frame buffer controller; and a memory unit coupled to the hierarchical tiler and the pixel-level comparator, the memory unit configured to store a change in the Z pyramid data structure responsive to an occlusion test result for a visible primitive before the pixel-level comparator determines whether pixel level values for the visible primitive need to be written by the frame buffer controller.