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


     FORTRAN SPECIFICATION
	  SUBROUTINE fglPolygonOffset( REAL*4 factor,
				       REAL*4 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.

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

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

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

	  fglPolygonOffset has no effect on selection.

     ERRORS
	  GL_INVALID_OPERATION is generated if fglPolygonOffset	is
	  executed between the execution of fglBegin and the
	  corresponding	execution of fglEnd.

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

	  fglGet with argument GL_POLYGON_OFFSET_FACTOR	or
	  GL_POLYGON_OFFSET_UNITS.

     SEE ALSO
	  fglDepthFunc,	fglDisable, fglEnable, fglGet, fglIsEnabled,
	  fglLineWidth,	fglStencilOp, fglTexEnv