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GLPOLYGONOFFSET()					     GLPOLYGONOFFSET()

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

C SPECIFICATION
       void glPolygonOffset( GLfloat factor,
			     GLfloat units )

       delim $$

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 appropri-
       ate 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 implementa-
       tion.  The offset is added before the depth test	is performed  and  be-
       fore the	value is written into the depth	buffer.

       glPolygonOffset	is useful for rendering	hidden-line images, for	apply-
       ing 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 feed-
       back buffer.

       glPolygonOffset has no effect on	selection.

ERRORS
       GL_INVALID_OPERATION is generated if glPolygonOffset  is	 executed  be-
       tween  the  execution  of  glBegin  and	the corresponding execution of
       glEnd.

ASSOCIATED GETS
       glIsEnabled  with  argument   GL_POLYGON_OFFSET_FILL,   GL_POLYGON_OFF-
       SET_LINE, or GL_POLYGON_OFFSET_POINT.

       glGet   with   argument	 GL_POLYGON_OFFSET_FACTOR  or  GL_POLYGON_OFF-
       SET_UNITS.

SEE ALSO
       glDepthFunc, glDisable, glEnable, glGet,	glIsEnabled, glLineWidth, glS-
       tencilOp, glTexEnv

							     GLPOLYGONOFFSET()

NAME | C SPECIFICATION | PARAMETERS | DESCRIPTION | NOTES | ERRORS | ASSOCIATED GETS | SEE ALSO

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