gluTessBeginPolygon - delimit a polygon description
C SPECIFICATION
void gluTessBeginPolygon( GLUtesselator* tess,
GLvoid* data )
PARAMETERS
tess Specifies the tessellation object (created with
gluNewTess).
data Specifies a pointer to user polygon data.
DESCRIPTION
gluTessBeginPolygon and gluTessEndPolygon delimit the def-
inition 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 tessel-
lated, 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);
SEE ALSO
gluNewTess, gluTessBeginContour, gluTessVertex,
gluTessCallback, gluTessProperty, gluTessNormal,
gluTessEndPolygon
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