Patent ID: 7382368

Claim:
A z operations unit, comprising: a source z evaluation unit configured to compute a source z value using tile specific coefficients for a plane equation defining a fragment of a source primitive, wherein the fragment is a portion of the source primitive that is within a tile, wherein the tile includes portions of at least two scanlines each of the tile specific coefficients based on a reference position within the tile wherein the reference position is unique to the tile and is not shared with any other tiles that are intersected by the primitive; a z triage unit configured to determine a minimum source z value and a maximum source z value for the fragment using the tile specific coefficients and produce a trivial z test result that indicates whether the fragment should be rejected, the fragment should be accepted, or that the source z value should be computed and compared with a destination z value; a destination z evaluation unit configured to receive destination z data from a z buffer and produce the destination z value; and a z test unit configured to determine whether or not the source z value or the destination z value should be stored in the z buffer.