Rendering in computer graphics systems

A graphics system having a rendering space divided into a plurality of rectangular areas and having each rectangular area sub-divided into a plurality of smaller rectangular areas, the graphics system comprising a processing unit configured to:

• receive an object list generated by a tiling process, referencing a set of polygons to be rendered in a selected one of the rectangular areas;
• and
• determine, for each polygon referenced in the received object list, whether that polygon intersects a selected one of the smaller rectangular areas in the selected rectangular area;
• wherein the processing unit is arranged to, for each polygon referenced in the received object list which is determined not to intersect the selected smaller rectangular area, perform no further processing of the polygon in the smaller rectangular area and for each polygon referenced in the received object list which is determined to intersect the selected smaller rectangular area, performing further processing of the polygon in the selected smaller rectangular area.

A graphics processing unit configured to render to a rendering space divided into a plurality of rectangular areas, each rectangular area being sub-divided into a plurality of smaller rectangular areas, the graphics processing unit comprising:

• an interface to a memory device;
• a microtiling unit configured to:
• receive via the interface an object list generated by a tiling process referencing a set of polygons to be rendered in a selected one of the rectangular areas,
• determine for each smaller rectangular area in the selected rectangular area whether that smaller rectangular area intersects a selected polygon, and
• output a corresponding indication;
• and
• a scan converter configured to receive the indications and, if a selected one of the smaller rectangular areas does not intersect the selected polygon, perform no further processing of the selected polygon in the respective smaller rectangular area or, if a selected one of the smaller rectangular areas does intersect the selected polygon, performing further processing of the polygon in the selected smaller rectangular area.