Coarse depth test in graphics processing systems

Coarse depth test hardware configured to perform coarse depth testing in a graphics processing system in which a rendering space is subdivided into a plurality of tiles, the coarse depth test hardware comprising:

• front depth test logic configured to:
• receive a set of one or more primitives or a set of one or more primitive fragments related to a tile of the plurality of tiles;
• obtain a depth range for the tile, the depth range for the tile identifying a depth range based on primitives or primitive fragments previously processed for the tile;
• and
• for at least one primitive of the set of one or more primitives or at least one primitive fragment of the set of one or more primitive fragments:
• make a determination, based on the depth range for the tile, as to whether the primitive or primitive fragment is in front of the primitives or primitive fragments previously processed for the tile according to a depth compare mode, and
• in response to making a determination that the primitive or primitive fragment is in front of the primitives or primitive fragments previously processed for the tile, identifying the primitive or primitive fragment as not requiring a read of a depth buffer to perform full resolution depth testing.