Method and apparatus for processing portions of primitives that are being rendered

A video graphics processor, comprising:

• a Z mask memory that stores representative buffered Z values for a plurality of pixel blocks that are included in a frame;
• a Z comparison block operably coupled to the Z mask memory, wherein the Z comparison block receives representative Z information for portions of primitives, wherein the Z comparison block compares the representative Z information for each portion with a representative buffered Z value for a corresponding pixel block, wherein the frame is divided into a plurality of pixel blocks and each portion of each primitive corresponds to a pixel block of the plurality of pixel blocks, wherein the Z comparison block provides an indication based on comparing the representative Z information for each portion with the representative buffered Z value for each corresponding pixel block;
• a raster engine operably coupled to the Z comparison block and operably coupled to receive primitive parameters of primitives, wherein the raster engine processes each primitive in portions, wherein the raster engine determines the representative Z information for each portion and provides the representative Z information for each portion to the Z comparison block, wherein when the Z comparison block indicates a favorable comparison for a portion, the raster engine discards the portion, wherein when the Z comparison block indicates an unfavorable comparison for the portion, the raster engine generates pixel fragments from the primitive parameters for the portion;
• and
• a render backend block operably coupled to the raster engine, wherein the render backend block blends the pixel fragments received from the raster engine with stored pixel data, wherein the stored pixel data includes stored color data and stored Z data.

A video graphics processor for processing primitives corresponding to a frame, comprising:

• a processing module;
• and
• memory operably coupled to the processing module, wherein the memory stores operating instructions that, when executed, cause the processing module to perform functions that include:
• separating each primitive into a plurality of portions, wherein each portion of the plurality of portions corresponds to a pixel block of a plurality of pixel blocks, wherein each pixel block of the plurality of pixel blocks includes a portion of a set of pixels that makes up the frame;
• determining a representative Z value for each portion of the primitive such that the processing module determines the representative buffered Z value by retrieving the representative buffered Z value from a Z mask memory;
• comparing the representative Z value for each portion with a representative buffered Z value corresponding to the portion;
• when the representative Z value for the portion compares favorably with the representative buffered Z value, discarding the portion;
• and
• when the representative Z value for the portion compares unfavorably with the representative buffered Z value, processing the portion of the primitive.