Graphics processing system and method of rendering

A method of rendering a frame showing a scene formed by primitives in a tile-based graphics processing system, the method comprising:

• a geometry processing phase, comprising the step of:
• tiling the primitives in the scene, to determine which primitives at least partially overlap which tiles of the frame to be rendered;
• and
• a rendering phase comprising the steps of:
• obtaining a fragment density map defining one or more texels, each texel corresponding to an area of the frame to be rendered and having an associated fragment size, wherein for each of the texels, the texel's height is an integer multiple of a native tile height used in the tile-based graphics processing system and the texel's width is an integer multiple of a native tile width used in the tile-based graphics processing system, and
• for each tile to be rendered:
• determining from the fragment density map a fragment size to be used to render the tile, performing sampling using the determined fragment size and performing fragment shading using the determined fragment size.