Graphics processing method and system for rendering items of geometry based on their size

A tile-based graphics processing system configured to render primitives using a rendering space which is sub-divided into a plurality of regions, wherein the graphics processing system comprises:

• geometry processing logic configured to perform a geometry processing phase for a current render comprising:
• receiving a set of primitives;
• and
• for each region in the plurality of regions:
• determining which primitives from the set of primitives are present in the region to thereby determine a plurality of primitives which are present in the region,
• determining, for each of the plurality of primitives which are present in a region, whether the primitive totally covers the region, and
• storing data for the plurality of primitives which are present in the region, wherein the stored data comprises primitive indication data for the region to indicate the determined plurality of primitives which are present in the region, and further comprises, for each of the plurality of primitives which are determined to totally cover the region, data to indicate total coverage of the region;
• and
• rendering logic configured to, after the geometry processing logic has completed the geometry processing phase for the current render, perform a rendering phase for each of the regions of the plurality of regions on a region-by-region basis for the current render, comprising:
• retrieving the stored data for the primitives which are present in the region,
• retrieving, based on the primitive indication data for the region, primitive data for the primitives which are present in the region,
• selectively processing the primitives which are present in the region based on the retrieved data to determine which sample points within the region are covered by the primitives, such that if the retrieved data includes data which indicates total coverage of the region for a particular primitive then the processing to determine which sample points within the region are covered by the particular primitive is skipped, and
• using the retrieved primitive data to determine rendered values at the sample points within the region based on the primitives which cover the respective sample points.

A non-transitory computer readable storage medium having stored thereon a computer readable dataset description of a graphics processing system that, when processed in an integrated circuit manufacturing system, causes the integrated circuit manufacturing system to manufacture an integrated circuit embodying the graphics processing system which is configured to render primitives using a rendering space which is sub-divided into a plurality of regions, wherein the graphics processing system comprises:

• geometry processing logic configured to perform a geometry processing phase for a current render comprising:
• receiving a set of primitives;
• and
• for each region in the plurality of regions:
• determining which primitives from the set of primitives are present in the region to thereby determine a plurality of primitives which are present in the region,
• determining, for each of the plurality of primitives which are present in a region, whether the primitive totally covers the region, and
• storing data for the plurality of primitives which are present in the region, wherein the stored data comprises primitive indication data for the region to indicate the determined plurality of primitives which are present in the region, and further comprises, for each of the plurality of primitives which are determined to totally cover the region, data to indicate total coverage of the region;
• and
• rendering logic configured to, after the geometry processing logic has completed the geometry processing phase for the current render, perform a rendering phase for each of the regions of the plurality of regions on a region-by-region basis for the current render, comprising:
• retrieving the stored data for the primitives which are present in the region,
• retrieving, based on the primitive indication data for the region, primitive data for the primitives which are present in the region,
• selectively processing the primitives which are present in the region based on the retrieved data to determine which sample points within the region are covered by the primitives, such that if the retrieved data includes data which indicates total coverage of the region for a particular primitive then the processing to determine which sample points within the region are covered by the particular primitive is skipped, and
• using the retrieved primitive date to determine rendered values at the sample points within the region based on the primitives which cover the respective sample points.