GLUTESSBEGINPOLYGON

Section: Misc. Reference Manual Pages (3G)
Index
Return to Main Contents

NAME

gluTessBeginPolygon - delimit a polygon description

C SPECIFICATION

void gluTessBeginPolygon( GLUtesselator* tess,


                            GLvoid* data )

delim $$

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);

This document was created by man2html, using the manual pages.
Time: 10:15:40 GMT, April 26, 2024