Methods of and apparatus for processing computer graphics

A graphics processing pipeline comprising:

• a rasteriser that generates graphics fragments each representing a set of sampling points for a given level of anti-aliasing,
• one or more later processing stages that perform per-fragment processing operations;
• and
• one or more later processing stages that perform per-sample processing operations and that are configured to natively support a lower level of multisampled anti-aliasing;
• wherein:
• the rasteriser is configured to pass graphics fragments that the rasteriser generates to the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations and to the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations for processing;
• the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations are configured to:
• when processing graphics fragments representing sets of sampling points for a higher level of anti-aliasing that is higher than the lower level of anti-aliasing that the one or more later processing stages that perform per-sample processing operations are configured to natively support, process each graphics fragment representing a set of sampling points for the higher level of anti-aliasing that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel;
• and
• when processing graphics fragments representing a set of sampling points for the lower level of anti-aliasing that the one or more later processing stages that perform per-sample processing operations are configured to natively support, process each graphics fragment representing a set of sampling points for the lower level of anti-aliasing that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel;
• and
• the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations are configured to:
• when processing graphics fragments representing a set of sampling points for a higher level of anti-aliasing that is higher than the lower level of anti-aliasing that the one or more later processing stages that perform per-sample processing operations are configured to natively support, process each graphics fragment representing a set of sampling points for the higher level of anti-aliasing that they receive for processing in one or more processing passes, each such processing pass processing a sub-set of some but not all of the sampling points of the set of sampling points that the fragment represents;
• and
• when processing graphics fragments representing a set of sampling points for the lower level of anti-aliasing that the one or more later processing stages that perform per-sample processing operations are configured to natively support, process each graphics fragment representing a set of sampling points for the lower level of multisampled anti-aliasing that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel.

A graphics processing pipeline comprising:

• a rasteriser that generates graphics fragments each representing a set of sampling points to be processed;
• one or more later processing stages that perform per-fragment processing operations;
• and
• one or more later processing stages that perform per-sample processing operations;
• wherein:
• the rasteriser is configured to pass graphics fragments that the rasteriser generates to the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations and to the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations for processing;
• the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations are configured to, when performing a lower level of multisampled anti-aliasing, process each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel, and when performing a higher level of anti-aliasing process each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel;
• and
• the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations are configured to when performing the lower level of multisampled anti-aliasing process each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel, but when performing the higher level of anti-aliasing process each graphics fragment that they receive for processing in one or more processing passes, each such processing pass processing a sub-set of some but not all of the sampling points of the set of sampling points that the fragment represents.

A non-transitory computer readable storage medium storing computer software code which when executing on a processor performs a method of carrying out a higher level of multisampled anti-aliasing in a graphics processing pipeline having a plurality of processing stages, at least some of which are configured to natively support a lower level of multisampled anti-aliasing, the method comprising:

• when performing the higher level of multisampled anti-aliasing:
• the rasteriser of the graphics processing pipeline generating graphics fragments each representing a set of sampling points for the higher level of anti-aliasing, and passing those fragments representing the set of sampling points for the higher level of anti-aliasing to one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations and to one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations for processing;
• the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations processing each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel;
• and
• the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations processing each graphics fragment that they receive for processing in one or more processing passes, each such processing pass processing a sub-set of some but not all of the sampling points of the set of sampling points that the fragment represents;
• and the method further comprising:
• when performing the lower level of multisampled anti-aliasing:
• the rasteriser of the graphics processing pipeline generating graphics fragments each representing a set of sampling points for the lower level of anti-aliasing, and passing those fragments representing the set of sampling points for the lower level of anti-aliasing to one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations and to one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations for processing;
• the one or more later processing stages of the graphics processing pipeline that perform per-fragment processing operations processing each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel;
• and
• the one or more later processing stages of the graphics processing pipeline that perform per-sample processing operations processing each graphics fragment that they receive for processing in a processing pass that processes all the sampling points that the fragment represents in parallel.