fgluTessBeginPolygon(3G)

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