OpenGL.GL.NV.fragment_program4

OpenGL extension NV.fragment_program4

This module customises the behaviour of the OpenGL.raw.GL.NV.fragment_program4 to provide a more Python-friendly API

Overview (from the spec)

This extension builds on the common assembly instruction set infrastructure provided by NV_gpu_program4, adding fragment program-specific features.

This extension provides interpolation modifiers to fragment program attributes allowing programs to specify that specified attributes be flat-shaded (constant over a primitive), centroid-sampled (multisample rendering), or interpolated linearly in screen space. The set of input and output bindings provided includes all bindings supported by ARB_fragment_program. Additional input bindings are provided to determine whether fragments were generated by front- or back-facing primitives ("fragment.facing"), to identify the individual primitive used to generate the fragment ("primitive.id"), and to determine distances to user clip planes ("fragment.clip[n]"). Additionally generic input attributes allow a fragment program to receive a greater number of attributes from previous pipeline stages than possible using only the pre-defined fixed-function attributes.

By and large, programs written to ARB_fragment_program can be ported directly by simply changing the program header from "!!ARBfp1.0" to "!!NVfp4.0", and then modifying instructions to take advantage of the expanded feature set. There are a small number of areas where this extension is not a functional superset of previous fragment program extensions, which are documented in the NV_gpu_program4 specification.

The official definition of this extension is available here: http://www.opengl.org/registry/specs/NV/fragment_program4.txt