# OpenGL.GL.AMD.interleaved_elements

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

## Functions

## Constants

GL_ALPHA (6406)

GL_BLUE (6405)

GL_GREEN (6404)

GL_RED (6403)

GL_RG16UI (33338)

GL_RG8UI (33336)

GL_RGBA8UI (36220)

GL_VERTEX_ELEMENT_SWIZZLE_AMD (37284)

GL_VERTEX_ID_SWIZZLE_AMD (37285)