# OpenGL.GL.SGIX.reference_plane

OpenGL extension SGIX.reference_plane

This module customises the behaviour of the
OpenGL.raw.GL.SGIX.reference_plane to provide a more
Python-friendly API

Overview (from the spec)

This extension allows a group of coplanar primitives to be rendered
without depth-buffering artifacts. This is accomplished by generating
the depth values for all the primitives from a single ``reference plane''
rather than from the primitives themselves. This ensures that all the
primitives in the group have exactly the same depth value at any given
sample point, no matter what imprecision may exist in the original
specifications of the primitives or in the GL's coordinate transformation
process.

The reference plane is defined by a four-component plane equation.
When glReferencePlaneSGIX is called, equation is transformed by the
transpose-adjoint of a matrix that is the complete object-coordinate
to clip-coordinate transformation. The resulting clip-coordinate
coefficients are transformed by the current viewport when the reference
plane is enabled.

The reference plane is enabled and disabled with glEnable and glDisable.

If the reference plane is enabled, a fragment (xf,yf,zf) will have a
new z coordinate generated from (xf,yf) by giving it the same z value
that the reference plane would have at (xf,yf).

The official definition of this extension is available here:
http://www.opengl.org/registry/specs/SGIX/reference_plane.txt

## Functions

## Constants

GL_REFERENCE_PLANE_EQUATION_SGIX (33150)

GL_REFERENCE_PLANE_SGIX (33149)