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<?xml version="1.0" encoding="ISO-8859-1"?>
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<html
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><head><title>gluTessBeginPolygon</title><link rel="stylesheet" href="style.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.59.1"/><link rel="home" href="index.xml" title="PyOpenGL 2.0.1.07 Man Pages"/><link rel="up" href="reference-GLU.xml" title="GLU"/><link rel="previous" href="gluTessBeginContour.3G.xml" title="gluTessBeginContour"/><link rel="next" href="gluTessCallback.3G.xml" title="gluTessCallback"/></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">gluTessBeginPolygon</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="gluTessBeginContour.3G.xml">Prev</a></td><th width="60%" align="center">GLU</th><td width="20%" align="right"><a accesskey="n" href="gluTessCallback.3G.xml">Next</a></td></tr></table><hr/></div><div class="refentry" lang="en"><a name="gluTessBeginPolygon.3G"/><div class="titlepage"/><div class="refnamediv"><a name="gluTessBeginPolygon.3G-name"/><h2>Name</h2><p>gluTessBeginPolygon — delimit a polygon description</p></div><div class="refsynopsisdiv"><a name="gluTessBeginPolygon.3G-c_spec"/><h2>C Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code>void<tt>gluTessBeginPolygon</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code>GLUtesselator*<i><tt>tess</tt></i>, GLvoid*<i><tt>data</tt></i>);</code></td></tr></table></div><div class="refsynopsisdiv"><a name="gluTessBeginPolygon.3G-python_spec"/><h2>Python Specification</h2><table class="funcprototype" border="0" cellpadding="0" cellspacing="0"><tr><td valign="top"><code><tt>gluTessBeginPolygon</tt></code></td><td valign="top"><code>(</code></td><td valign="top"><code><i><tt>tess</tt></i>, <i><tt>data</tt></i>) →<tt>None</tt></code></td></tr></table></div><div class="refsect1" lang="en"><a name="gluTessBeginPolygon.3G-parameters"/><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><i><tt>tess</tt></i></span></dt><dd>
Specifies the tessellation object (created with <a href="gluNewTess.3G.xml"><tt>gluNewTess</tt></a>).
</dd><dt><span class="term"><i><tt>data</tt></i></span></dt><dd>
Specifies a pointer to user polygon data.
</dd></dl></div></div><div class="refsect1" lang="en"><a name="gluTessBeginPolygon.3G-description"/><h2>Description</h2><p>
<tt>gluTessBeginPolygon</tt> and <a href="gluTessEndPolygon.3G.xml"><tt>gluTessEndPolygon</tt></a> delimit the
definition of a convex, concave or self-intersecting polygon. Within each
<tt>gluTessBeginPolygon</tt>/<a href="gluTessEndPolygon.3G.xml"><tt>gluTessEndPolygon</tt></a> pair, there must be
one or more calls to <a href="gluTessBeginContour.3G.xml"><tt>gluTessBeginContour</tt></a>/<a href="gluTessBeginContour.3G.xml"><tt>gluTessEndContour</tt></a>. Within each contour, there are zero or more calls to <a href="gluTessVertex.3G.xml"><tt>gluTessVertex</tt></a>. The vertices specify a closed contour (the last vertex of each contour is
automatically linked to the first). See the <a href="gluTessVertex.3G.xml"><tt>gluTessVertex</tt></a>, <a href="gluTessBeginContour.3G.xml"><tt>gluTessBeginContour</tt></a>, and <a href="gluTessBeginContour.3G.xml"><tt>gluTessEndContour</tt></a>
reference pages for more details.
</p><p>
<i><tt>data</tt></i> is a pointer to a user-defined data structure. If the appropriate callback(s) are specified
(see <a href="gluTessCallback.3G.xml">gluTessCallback</a>), then this pointer is returned to the callback function(s). Thus, it is a convenient way to store
per-polygon information.
</p><p>
Once <a href="gluTessEndPolygon.3G.xml"><tt>gluTessEndPolygon</tt></a> is called, the polygon is tessellated, and the
resulting triangles are described through callbacks. See <a href="gluTessCallback.3G.xml"><tt>gluTessCallback</tt></a> for
descriptions of the callback functions.
</p></div><div class="refsect1" lang="en"><a name="gluTessBeginPolygon.3G-example"/><h2>Example</h2><p>
A quadrilateral with a triangular hole in it can be described as follows: gluTessBeginPolygon(tobj,
<tt>NULL</tt>); 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);
</p></div><div class="refsect1" lang="en"><a name="gluTessBeginPolygon.3G-see_also"/><h2>See Also</h2><p>
<span class="simplelist"><a href="gluNewTess.3G.xml">gluNewTess</a>, <a href="gluTessBeginContour.3G.xml">gluTessBeginContour</a>, <a href="gluTessVertex.3G.xml">gluTessVertex</a>, <a href="gluTessCallback.3G.xml">gluTessCallback</a>, <a href="gluTessProperty.3G.xml">gluTessProperty</a>, <a href="gluTessNormal.3G.xml">gluTessNormal</a>, <a href="gluTessEndPolygon.3G.xml">gluTessEndPolygon</a></span>
</p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="gluTessBeginContour.3G.xml">Prev</a></td><td width="20%" align="center"><a accesskey="u" href="reference-GLU.xml">Up</a></td><td width="40%" align="right"><a accesskey="n" href="gluTessCallback.3G.xml">Next</a></td></tr><tr><td width="40%" align="left" valign="top">gluTessBeginContour</td><td width="20%" align="center"><a accesskey="h" href="index.xml">Home</a></td><td width="40%" align="right" valign="top">gluTessCallback</td></tr></table></div></body></html>
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