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GLUTESSBEGINPOLYGON(3G)                                GLUTESSBEGINPOLYGON(3G)

NAME

       gluTessBeginPolygon - delimit a polygon description

C SPECIFICATION

       void gluTessBeginPolygon( GLUtesselator* tess,
                                 GLvoid* data )

PARAMETERS

       tess  Specifies the tessellation object (created with gluNewTess).

       data  Specifies a pointer to user polygon data.

DESCRIPTION

       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

       A  quadrilateral  with a triangular hole in it can be described as fol-
       lows:

       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

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



                                                       GLUTESSBEGINPOLYGON(3G)