Graphics processing systems

A graphics processing system comprising:

• partitioning processing circuitry configured to, when rendering a scene for output that includes a light source that could cast shadows, partition the world-space volume for the scene to be rendered into a plurality of sub-volumes;
• geometry set determining circuitry configured to determine, for at least one sub-volume that the world-space volume for the scene has been partitioned into, 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;
• and
• light source visibility parameter determining circuitry configured to determine, for at least one output sample for the scene being rendered, a light source visibility parameter using the determined set of geometry for a sub-volume that the world-space volume for the scene has been partitioned into.

A non-transitory computer readable storage medium storing computer software code which when executing on at least one processor performs a method of operating a graphics processing system when rendering a scene for output that includes a light source that could cast shadows, the method comprising:

• partitioning by processing circuitry the world-space volume for the scene to be rendered into a plurality of sub-volumes;
• for at least one sub-volume for the scene being rendered:
• determining by processing circuitry 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;
• and
• for at least one output sample for the scene being rendered:
• determining by processing circuitry a light source visibility parameter using the determined set of geometry for a sub-volume that the world-space volume for the scene has been partitioned into.