| | '''OpenGL extension AMD.interleaved_elements |
| | |
| | This module customises the behaviour of the |
| | OpenGL.raw.GL.AMD.interleaved_elements to provide a more |
| | Python-friendly API |
| | |
| | Overview (from the spec) |
| | |
| | The glDrawElements function and its variants (instanced and indirect, |
| | for example) allow OpenGL to draw indexed arrays of vertices. Since its |
| | inception, OpenGL has supported unsigned bytes, unsigned shorts and |
| | unsigned integers as index types. However, all enabled vertex arrays may |
| | be represented by at most one shared index. |
| | |
| | A common scenario in graphics rendering is that several faces share |
| | a vertex where, for each face some properties of a vertex (position and |
| | texture coordinates, for example) should be common but others must be |
| | unique (colors, normals, and so on). Consider a mesh of a cube with |
| | per-face normals, for example. There are 8 vertices and 6 normals, and 12 |
| | triangles (where each face of the cube is represented as two triangles). |
| | To render this cube, we must compute the 24 unique permutations of |
| | position and normal and build a new element list to index into it. In |
| | fact, any advantage of indexed draw is lost here as the number of required |
| | permutations is equal to the final vertex count required to draw the |
| | object. |
| | |
| | This extension allows OpenGL to process multi-component packed element |
| | data. The maximum size of a vertex's index data is not increased, but the |
| | facility to store 2 16-bit or 2 or 4 8-bit indices per vertex is introduced. |
| | Each vertex attribute is given a swizzle property to allow its index to |
| | be sourced from one of up to 4 channels of index data. This effectively |
| | allows an application to supply multiple interleaved streams of index data |
| | to OpenGL. Each vertex attribute is given a 'channel selector' to select |
| | one of the up to 4 channels of vertex index information presented to |
| | OpenGL. This enables the use-case described above and many more. |
| | The swizzle parameter is also applied to vertex indices passed to shaders, |
| | and updates to the definition of base vertex parameters and primitive |
| | restart are applied. |
| | |
| | The official definition of this extension is available here: |
| | http://www.opengl.org/registry/specs/AMD/interleaved_elements.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.AMD.interleaved_elements import * |
| | from OpenGL.raw.GL.AMD.interleaved_elements import _EXTENSION_NAME |
| |
|
| | def glInitInterleavedElementsAMD(): |
| | '''Return boolean indicating whether this extension is available''' |
| | from OpenGL import extensions |
| | return extensions.hasGLExtension( _EXTENSION_NAME ) |
| |
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| |
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| | |
