Reducing redundant rendering in a graphics system

Abstract

A render is performed using a tile-based graphics pipeline where a rendering space is sub-divided into tiles. Primitives are received that were processed by a geometry processing stage of the graphics pipeline and are grouped into sets, and a primitive block is generated from each set. Primitive block data is stored characterising the content of the primitive blocks. It is determined which tile each of the primitives are located in, and for at least one selected tile a per-tile primitive block list is stored indicating which of the primitive blocks contain primitives located in that tile. It is determined whether the output of a previous render for the selected tile(s) can be used as an output for the render based on the per-tile primitive block list and the primitive block data for the primitive blocks indicated therein, and corresponding data from the previous render.