GLUTESSBEGINPOLYGON(3G) |  | GLUTESSBEGINPOLYGON(3G)

# NAME

gluTessBeginPolygon - delimit a polygon description

# C SPECIFICATION

void gluTessBeginPolygon( GLUtesselator* tess,
GLvoid* data )
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# 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 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

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