NAME
	  glPolygonOffset - set	the scale and units used to calculate
	  depth	values


     C SPECIFICATION
	  void glPolygonOffset(	GLfloat	factor,
				GLfloat	units )


     PARAMETERS
	  factor  Specifies a scale factor that	is used	to create a
		  variable depth offset	for each polygon. The initial
		  value	is 0.

	  units	  Is multiplied	by an implementation-specific value to
		  create a constant depth offset. The initial value is
		  0.

     DESCRIPTION
	  When GL_POLYGON_OFFSET is enabled, each fragment's depth
	  value	will be	offset after it	is interpolated	from the depth
	  values of the	appropriate vertices.  The value of the	offset
	  is factor * DZ  +  r * units,	where DZ  is a measurement of
	  the change in	depth relative to the screen area of the
	  polygon, and r is the	smallest value that is guaranteed to
	  produce a resolvable offset for a given implementation.  The
	  offset is added before the depth test	is performed and
	  before the value is written into the depth buffer.

	  glPolygonOffset is useful for	rendering hidden-line images,
	  for applying decals to surfaces, and for rendering solids
	  with highlighted edges.

     NOTES
	  glPolygonOffset is available only if the GL version is 1.1
	  or greater.

	  glPolygonOffset has no effect	on depth coordinates placed in
	  the feedback buffer.

	  glPolygonOffset has no effect	on selection.

     ERRORS
	  GL_INVALID_OPERATION is generated if glPolygonOffset is
	  executed between the execution of glBegin and	the
	  corresponding	execution of glEnd.

     ASSOCIATED	GETS
	  glIsEnabled with argument GL_POLYGON_OFFSET_FILL,
	  GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT.

	  glGet	with argument GL_POLYGON_OFFSET_FACTOR or
	  GL_POLYGON_OFFSET_UNITS.

     SEE ALSO
	  glDepthFunc, glDisable, glEnable, glGet, glIsEnabled,
	  glLineWidth, glStencilOp, glTexEnv