Native bindings to the EXT_texture_buffer extension.

This extension provides a new texture type, called a buffer texture. Buffer textures are one-dimensional arrays of texels whose storage comes from an attached buffer object. When a buffer object is bound to a buffer texture, a format is specified, and the data in the buffer object is treated as an array of texels of the specified format.

The use of a buffer object to provide storage allows the texture data to be specified in a number of different ways: via buffer object loads (BufferData), direct CPU writes (MapBuffer), or framebuffer readbacks to pixel buffer objects (ReadPixels). A buffer object can also be loaded by transform feedback, which captures selected transformed attributes of vertices processed by the GL. Several of these mechanisms do not require an extra data copy, which would be required when using conventional TexImage-like entry points.

Buffer textures do not support mipmapping, texture lookups with normalized floating-point texture coordinates, and texture filtering of any sort. They can be accessed via single texel fetch operations in programmable shaders, using a new sampler type and texel fetch function, and access can be controlled using the same memory barrier operations as for other texture types.

Buffer textures are treated as (potentially large) one-dimensional textures; the maximum texture size supported for buffer textures in the initial implementation of this extension is 2²⁷ texels (note that this extension only guarantees support for buffer textures with 2¹⁶ texels, but we expect most implementations to exceed that substantially). When a buffer object is attached to a buffer texture, a size is not specified; rather, the number of texels in the texture is taken by dividing the size of the buffer object by the size of each texel.

This extension also allows a sub-range of the buffer's data store to be attached to a texture. This can be used, for example, to allow multiple buffer textures to be backed by independent sub-ranges of the same buffer object, or for different sub-ranges of a single buffer object to be used for different purposes.