Graphics processing

摘要

A graphics processor includes a vertex shader 20 that processes input attribute values from a vertex buffer 26 to generate output vertex shaded attribute values 28 to be used by a rasteriser/fragment shader 22 of the graphics processor when processing an image for display. Vertex shader output attributes for which the vertex shader input attributes that the vertex shader output attribute depends on are defined solely on a per-vertex basis or solely on a per-instance basis are identified. Then, for such vertex shader output attributes, the vertex shader 20 stores, for use by the rasteriser/fragment shader 22 of the graphics processor when processing an image for display, only one copy of the vertex shader output attribute for a given vertex or instance, respectively, irrespective of the number of instances or vertices, respectively, that the output attribute value applies to.

主权项

1. A method of operating a graphics processing system which includes a vertex shading stage which processes input attribute values to generate output vertex shaded attribute values for use by a subsequent stage or stages of the graphics processing system, the method comprising:
when the vertex shading stage is operating in instanced mode, for a given draw call:
identifying vertex shader output attributes to be generated by the vertex shading stage for which the vertex shader input attributes that the vertex shader output attribute depends on are defined solely on a per-vertex basis or solely on a per-instance basis; andwhen it is recognised that the vertex shader input attributes that a vertex shader output attribute to be generated depends on are defined solely on a per-vertex basis or solely on a per-instance basis:the vertex shading stage:in a case that the vertex shader output attribute depended solely on per-vertex defined input attributes storing only one copy of the vertex shader output attribute value to be generated by the vertex shading stage for use by the subsequent stage or stages of the graphics processing system for a given vertex, irrespective of a number of instances that the output attribute value applies to; andin a case that the vertex shader output attribute depended solely on per-instance defined input attributes storing only one copy of the vertex shader output attribute value to be generated by the vertex shading stage for use by the subsequent stage or stages of the graphics processing system for a given instance, irrespective of a number of vertices that the output attribute value applies to; anda subsequent graphics processing stage or stages:in the case that the output attribute depended solely on per-vertex defined input attributes, using the single stored vertex shader output attribute value for a given vertex for each instance that the output attribute value applies to; andin the case that the output attribute depended solely on per-instance defined input attributes, using the single stored vertex shader output attribute value for a given instance for each vertex that the output attribute value applies to.