NAME
	  fgluTessBeginPolygon - delimit a polygon description


     FORTRAN SPECIFICATION
	  SUBROUTINE fgluTessBeginPolygon( CHARACTER*8 tess,
					   CHARACTER*8 data )


     PARAMETERS
	  tess	Specifies the tessellation object (created with
		fgluNewTess).

	  data	Specifies a pointer to user polygon data.

     DESCRIPTION
	  fgluTessBeginPolygon and fgluTessEndPolygon delimit the
	  definition of	a convex, concave or self-intersecting
	  polygon. Within each fgluTessBeginPolygon/fgluTessEndPolygon
	  pair,	there must be one or more calls	to
	  fgluTessBeginContour/fgluTessEndContour. Within each
	  contour, there are zero or more calls	to fgluTessVertex. The
	  vertices specify a closed contour (the last vertex of	each
	  contour is automatically linked to the first). See the
	  fgluTessVertex, fgluTessBeginContour,	and fgluTessEndContour
	  reference pages for more details.

	  data is a pointer to a user-defined data structure. If the
	  appropriate callback(s) are specified	(see
	  fgluTessCallback), then this pointer is returned to the
	  callback function(s).	Thus, it is a convenient way to	store
	  per-polygon information.

	  Once fgluTessEndPolygon is called, the polygon is
	  tessellated, and the resulting triangles are described
	  through callbacks.  See fgluTessCallback for descriptions of
	  the callback functions.

     EXAMPLE
	  A quadrilateral with a triangular hole in it can be
	  described as follows:

	  gluTessBeginPolygon(tobj, NULL);
	   gluTessBeginContour(tobj);
	     gluTessVertex(tobj, v1, v1);
	     gluTessVertex(tobj, v2, v2);
	     gluTessVertex(tobj, v3, v3);
	     gluTessVertex(tobj, v4, v4);
	   gluTessEndContour(tobj);
	   gluTessBeginContour(tobj);
	     gluTessVertex(tobj, v5, v5);
	     gluTessVertex(tobj, v6, v6);
	     gluTessVertex(tobj, v7, v7);
	   gluTessEndContour(tobj); gluTessEndPolygon(tobj);


     SEE ALSO
	  fgluNewTess, fgluTessBeginContour, fgluTessVertex,
	  fgluTessCallback, fgluTessProperty, fgluTessNormal,
	  fgluTessEndPolygon