Delimits a polygon description.
C bindings library: libGL.a
void gluTessBeginPolygon( GLUtesselator* tess, GLvoid* data )
The gluTessBeginPolygon and gluTessEndPolygon routines 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.
The parameter 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.
| tess | Specifies the tessellation object (created with gluNewTess). |
| data | Specifies a pointer to user polygon data. |
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);
gluNewTess subroutine, gluTessBeginContour subroutine, gluTessVertex subroutine, gluTessCallback subroutine, gluTessProperty subroutine, gluTessNormal subroutine, gluTessEndPolygon subroutine.