OpenGL extension EXT.blend_color
This module customises the behaviour of the OpenGL.raw.GL.EXT.blend_color to provide a more Python-friendly API
Overview (from the spec)
Blending capability is extended by defining a constant color that can be included in blending equations. A typical usage is blending two RGB images. Without the constant blend factor, one image must have an alpha channel with each pixel set to the desired blend factor.
The official definition of this extension is available here:
Return boolean indicating whether this extension is available