OpenGL.GL.INTEL.fragment_shader_ordering

OpenGL extension INTEL.fragment_shader_ordering

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

Overview (from the spec)

Graphics devices may execute in parallel fragment shaders referring to the same window xy coordinates. Framebuffer writes are guaranteed to be processed in primitive rasterization order, but there is no order guarantee for other instructions and image or buffer object accesses in particular.

The extension introduces a new GLSL built-in function, beginFragmentShaderOrderingINTEL(), which blocks execution of a fragment shader invocation until invocations from previous primitives that map to the same xy window coordinates (and same sample when per-sample shading is active) complete their execution. All memory transactions from previous fragment shader invocations are made visible to the fragment shader invocation that called beginFragmentShaderOrderingINTEL() when the function returns.

Including the following line in a shader can be used to control the language features described in this extension:

#extension GL_INTEL_fragment_shader_ordering : <behavior>

where <behavior> is as specified in section 3.3.

New preprocessor #defines are added to the OpenGL Shading Language:

#define GL_INTEL_fragment_shader_ordering 1

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