Abstract: When rendering a scene for output that includes a light source that could cast shadows in a graphics processing system, the world-space volume for the scene to be rendered is first partitioned into a plurality of sub-volumes, and then a set of geometry to be processed for the scene that could cast a shadow from a light source to be considered for the scene in the sub-volume is determined for any sub-volume that is lit by a light source. The determined sets of geometry for the sub-volumes are then used to determine light source visibility parameters for output samples, such as vertex positions and/or screen space sampling positions, for the scene. The determined light source visibility parameter for an output sample is then used to modulate the effect of the light source at the output sample when rendering an output version of the output sample.

Abstract: To simulate the effect of shadows in an image being rendered a light source bounding frustum is produced for a tile for a light source, and used to determine a set of geometry for the tile that could cast a shadow in the tile. The determined set of geometry is then used to determine a light source visibility parameter for each sampling position in the tile by determining for each tile screen space sampling position, whether rays cast between the tile sampling position and a set of sampling positions representing the light source would intersect occluding geometry or not. The determined number of visible light source sampling positions for each tile sampling position is used to determine a light source visibility parameter value for each tile sampling position, and the determined light source visibility parameters are then used to modulate the light source when shading the geometry.

Abstract: A graphics processing system performs a final gather process so as to generate final gather lighting data for a scene. The final gather process comprises casting sampling rays from a final gather point within the scene. Radiosity data provided for the scene is sampled using the sampling rays cast from the final gather point. Final gather lighting data is then generated from the sampled radiosity data. The sampling rays are cast from the final gather point in an informed manner based on directional irradiance data provided for the scene. The final gather process can therefore be carried out by the graphics processing system more efficiently and effectively.

Abstract: To simulate the effect of shadows in an image being rendered a light source bounding frustum is produced for a tile for a light source, and used to determine a set of geometry for the tile that could cast a shadow in the tile. The determined set of geometry is then used to determine a light source visibility parameter for each sampling position in the tile by determining for each tile screen space sampling position, whether rays cast between the tile sampling position and a set of sampling positions representing the light source would intersect occluding geometry or not. The determined number of visible light source sampling positions for each tile sampling position is used to determine a light source visibility parameter value for each tile sampling position, and the determined light source visibility parameters are then used to modulate the light source when shading the geometry.