OpenGL extension EXT.rescale_normal
This module customises the behaviour of the OpenGL.raw.GL.EXT.rescale_normal to provide a more Python-friendly API
Overview (from the spec)
When normal rescaling is enabled a new operation is added to the transformation of the normal vector into eye coordinates. The normal vector is rescaled after it is multiplied by the inverse modelview matrix and before it is normalized.
The rescale factor is chosen so that in many cases normal vectors with unit length in object coordinates will not need to be normalized as they are transformed into eye coordinates.
The official definition of this extension is available here: