gluTessBeginPolygon.3G - Man Page

void gluTessBeginPolygon( GLUtesselator* tess,

	GLvoid* data )

tess

Specifies the tessellation object (created with gluNewTess).

data

Specifies a pointer to user polygon data.

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.

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(3G), gluTessBeginContour(3G), gluTessVertex(3G),  gluTessCallback(3G), gluTessProperty(3G), gluTessNormal(3G), gluTessEndPolygon(3G)

gluBeginPolygon.3G(3), gluNewTess.3G(3), gluTessBeginContour.3G(3), gluTessCallback.3G(3), gluTessEndPolygon.3G(3), gluTessNormal.3G(3), gluTessVertex.3G(3).