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Manual Reference Pages  - GLUTESSBEGINPOLYGON (3G)

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gluTessBeginPolygon - delimit a polygon description

CONTENTS

C Specification
Parameters
Description
Example
See Also

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:

.Ex 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);
.Ee

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

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