essVertex(tobj, v5, v5);
      gluTessVertex(tobj, v6, v6);
      gluTessVertex(tobj, v7, v7);
   gluTessEndContour(tobj);
gluTessEndPolygon(tobj);
            </pre><p>
            In the above example the pointers,
            <math overflow="scroll"><mi mathvariant="italic">v1</mi></math>
            through
            <math overflow="scroll"><mi mathvariant="italic">v7</mi></math>,
            should point to different
            addresses,
            since the values stored at these addresses will n