OpenGL extension SGIX.fog_offset
This module customises the behaviour of the OpenGL.raw.GL.SGIX.fog_offset to provide a more Python-friendly API
Overview (from the spec)
This extension allows fragments to look brighter in a foggy environment, by biasing the fragment eye-coordinate distance prior to fog computation. A reference point in eye space (rx ry rz) and an offset amount toward the viewpoint (f_o) are specified. When fog offset is enabled, the offset amount will be subtracted from the fragment distance, making objects appear less foggy.
If fog computation is done in screen-space coordinates under perspective projection, the reference point is used in adjusting the fog offset to be correct for fragments whose depth is close to that point. The reference point should be redefined when it becomes too far away from the primitives being drawn. Under orthographic projection, or if fog computation is done in eye-space coordinates, the reference point is ignored.
The official definition of this extension is available here: