Graphics processing renders a scene with a plurality of different rendering parameters for different locations on a screen area. Each primitive of a batch of primitives belonging to an object covering at least two of the zones of the screen area is assembled to a screen space. Assembling each of the primitives includes iterating each primitive with a primitive assembler for each of the zones covered by the object. Each said zone is associated with a different set of screen space transform parameters used to transform locations of vertices in the batch of primitives from a homogenous coordinate space to a screen space that is not flat. The zones are arranged to minimize an overlap between zones.