Patent ID: 9741159
Date: 2017-08-22
CPC Classifications: G06T

Claim:
1. A method of operating a graphics processing system when rendering a frame for output that includes a light source, the method comprising: for at least one region of the frame being rendered: determining by processing circuitry a set of the geometry to be processed for the frame that could cast a shadow in the frame region being rendered from a light source to be considered for the frame, wherein the set of geometry that could cast a shadow comprises one or more geometry objects that do not form part of the light source; and for each sampling position of a set of sampling positions for the region of the frame being rendered, determining by processing circuitry a light source visibility parameter using the determined set of geometry for the frame region that could cast a shadow from the light source; wherein the step of determining the set of geometry for the frame region that could cast a shadow from the light source comprises: determining one or more light source bounding frustums that contain geometry that is visible in the frame region and the light source being considered; determining for geometry objects for the frame that do not form part of the light source, whether or not they intersect at least one of the light source bounding frustums for the frame region; and when it is determined that a geometry object for the frame that does not form part of the light source intersects at least one of the light source bounding frustums for the frame region, including that geometry object in the set of geometry for the frame region that could cast a shadow from the light source.