gluTessBeginPolygon(3G)	       OpenGL Reference	       gluTessBeginPolygon(3G)

NAME    [Toc]    [Back]

     gluTessBeginPolygon - delimit a polygon description

C SPECIFICATION    [Toc]    [Back]

     void gluTessBeginPolygon( GLUtesselator* tess,
			       GLvoid* data )

PARAMETERS    [Toc]    [Back]

     tess  Specifies the tessellation object (created with gluNewTess).

     data  Specifies a pointer to user polygon data.

DESCRIPTION    [Toc]    [Back]

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

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

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

EXAMPLE    [Toc]    [Back]

     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);











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gluTessBeginPolygon(3G)	       OpenGL Reference	       gluTessBeginPolygon(3G)



	   gluTessBeginContour(tobj);
	     gluTessVertex(tobj, v5, v5);
	     gluTessVertex(tobj, v6, v6);
	     gluTessVertex(tobj, v7, v7);
	   gluTessEndContour(tobj);
	  gluTessEndPolygon(tobj);

SEE ALSO    [Toc]    [Back]

     gluNewTess, gluTessBeginContour, gluTessVertex, gluTessCallback,
     gluTessProperty, gluTessNormal, gluTessEndPolygon


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