| '''OpenGL extension ARB.gpu_shader5 |
| |
| This module customises the behaviour of the |
| OpenGL.raw.GL.ARB.gpu_shader5 to provide a more |
| Python-friendly API |
| |
| Overview (from the spec) |
| |
| This extension provides a set of new features to the OpenGL Shading |
| Language and related APIs to support capabilities of new GPUs, extending |
| the capabilities of version 1.50 of the OpenGL Shading Language. Shaders |
| using the new functionality provided by this extension should enable this |
| functionality via the construct |
| |
| #extension GL_ARB_gpu_shader5 : require (or enable) |
| |
| This extension provides a variety of new features for all shader types, |
| including: |
| |
| * support for indexing into arrays of samplers using non-constant |
| indices, as long as the index doesn't diverge if multiple shader |
| invocations are run in lockstep; |
| |
| * extending the uniform block capability of OpenGL 3.1 and 3.2 to allow |
| shaders to index into an array of uniform blocks; |
| |
| * support for implicitly converting signed integer types to unsigned |
| types, as well as more general implicit conversion and function |
| overloading infrastructure to support new data types introduced by |
| other extensions; |
| |
| * a "precise" qualifier allowing computations to be carried out exactly |
| as specified in the shader source to avoid optimization-induced |
| invariance issues (which might cause cracking in tessellation); |
| |
| * new built-in functions supporting: |
| |
| * fused floating-point multiply-add operations; |
| |
| * splitting a floating-point number into a significand and exponent |
| (frexp), or building a floating-point number from a significand and |
| exponent (ldexp); |
| |
| * integer bitfield manipulation, including functions to find the |
| position of the most or least significant set bit, count the number |
| of one bits, and bitfield insertion, extraction, and reversal; |
| |
| * packing and unpacking vectors of small fixed-point data types into a |
| larger scalar; and |
| |
| * convert floating-point values to or from their integer bit |
| encodings; |
| |
| * extending the textureGather() built-in functions provided by |
| ARB_texture_gather: |
| |
| * allowing shaders to select any single component of a multi-component |
| texture to produce the gathered 2x2 footprint; |
| |
| * allowing shaders to perform a per-sample depth comparison when |
| gathering the 2x2 footprint using for shadow sampler types; |
| |
| * allowing shaders to use arbitrary offsets computed at run-time to |
| select a 2x2 footprint to gather from; and |
| |
| * allowing shaders to use separate independent offsets for each of the |
| four texels returned, instead of requiring a fixed 2x2 footprint. |
| |
| This extension also provides some new capabilities for individual |
| shader types, including: |
| |
| * support for instanced geometry shaders, where a geometry shader may be |
| run multiple times for each primitive, including a built-in |
| gl_InvocationID to identify the invocation number; |
| |
| * support for emitting vertices in a geometry program where each vertex |
| emitted may be directed independently at a specified vertex stream (as |
| provided by ARB_transform_feedback3), and where each shader output is |
| associated with a stream; |
| |
| * support for reading a mask of covered samples in a fragment shader; |
| and |
| |
| * support for interpolating a fragment shader input at a programmable |
| offset relative to the pixel center, a programmable sample number, or |
| at the centroid. |
| |
| The official definition of this extension is available here: |
| http://www.opengl.org/registry/specs/ARB/gpu_shader5.txt |
| ''' |
| from OpenGL import platform, constant, arrays |
| from OpenGL import extensions, wrapper |
| import ctypes |
| from OpenGL.raw.GL import _types, _glgets |
| from OpenGL.raw.GL.ARB.gpu_shader5 import * |
| from OpenGL.raw.GL.ARB.gpu_shader5 import _EXTENSION_NAME |
|
|
| def glInitGpuShader5ARB(): |
| '''Return boolean indicating whether this extension is available''' |
| from OpenGL import extensions |
| return extensions.hasGLExtension( _EXTENSION_NAME ) |
|
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| |
