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Name

gluTessBeginPolygon - delimit a polygon description

C Specification

void gluTessBeginPolygon( GLUtesselator* tess, 
    GLvoid* data )

eqn not supported

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)

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