OpenGL extension NV.texture_compression_vtc
This module customises the behaviour of the OpenGL.raw.GL.NV.texture_compression_vtc to provide a more Python-friendly API
Overview (from the spec)
This extension adds support for the VTC 3D texture compression formats, which are analogous to the S3TC texture compression formats, with the addition of some retiling in the Z direction. VTC has the same compression ratio as S3TC and uses 4x4x1, 4x4x2, (4x4x3 when non-power-of-two textures are supported), or 4x4x4 blocks.
The official definition of this extension is available here:
Return boolean indicating whether this extension is available