upstream-doc/man2/gluTessEndPolygon.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="gluTessEndPolygon">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>gluTessEndPolygon</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>gluTessEndPolygon</refname>
  17         <refpurpose>delimit a polygon description</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>gluTessEndPolygon</function></funcdef>
  23                 <paramdef>GLUtesselator* <parameter>tess</parameter></paramdef>
  24             </funcprototype>
  25         </funcsynopsis>
  26     </refsynopsisdiv>
  27     <!-- eqn: ignoring delim $$ -->
  28     <refsect1 id="parameters"><title>Parameters</title>
  29         <variablelist>
  30         <varlistentry>
  31             <term><parameter>tess</parameter></term>
  32             <listitem>
  33                 <para>
  34                     Specifies the tessellation object (created with <citerefentry><refentrytitle>gluNewTess</refentrytitle></citerefentry>).
  35                 </para>
  36             </listitem>
  37         </varlistentry>
  38         </variablelist>
  39     </refsect1>
  40     <refsect1 id="description"><title>Description</title>
  41         <para>
  42             <citerefentry><refentrytitle>gluTessBeginPolygon</refentrytitle></citerefentry> and <function>gluTessEndPolygon</function> delimit the
  43             definition of a convex, concave, or self-intersecting polygon. Within
  44             each <citerefentry><refentrytitle>gluTessBeginPolygon</refentrytitle></citerefentry>/<function>gluTessEndPolygon</function> pair, there must be
  45             one or more calls to <citerefentry><refentrytitle>gluTessBeginContour</refentrytitle></citerefentry>/<citerefentry><refentrytitle>gluTessEndContour</refentrytitle></citerefentry>.
  46             Within each contour, there are zero or more calls to <citerefentry><refentrytitle>gluTessVertex</refentrytitle></citerefentry>.
  47             The vertices specify a closed contour (the last vertex of each contour
  48             is automatically linked to the first). See the <citerefentry><refentrytitle>gluTessVertex</refentrytitle></citerefentry>,
  49             <citerefentry><refentrytitle>gluTessBeginContour</refentrytitle></citerefentry>, and <citerefentry><refentrytitle>gluTessEndContour</refentrytitle></citerefentry> reference pages for
  50             more details.
  51         </para>
  52         <para>
  53             Once <function>gluTessEndPolygon</function> is called, the polygon is tessellated, and the
  54             resulting triangles are described through callbacks.
  55             See <citerefentry><refentrytitle>gluTessCallback</refentrytitle></citerefentry> for descriptions of the callback functions.
  56         </para>
  57     </refsect1>
  58     <refsect1 id="example"><title>Example</title>
  59         <para>
  60             A quadrilateral with a triangular hole in it can be described like this:
  61             <programlisting>
  62 gluTessBeginPolygon(tobj, NULL);
  63    gluTessBeginContour(tobj);
  64       gluTessVertex(tobj, v1, v1);
  65       gluTessVertex(tobj, v2, v2);
  66       gluTessVertex(tobj, v3, v3);
  67       gluTessVertex(tobj, v4, v4);
  68    gluTessEndContour(tobj);
  69    gluTessBeginContour(tobj);
  70       gluTessVertex(tobj, v5, v5);
  71       gluTessVertex(tobj, v6, v6);
  72       gluTessVertex(tobj, v7, v7);
  73    gluTessEndContour(tobj);
  74 gluTessEndPolygon(tobj);
  75             </programlisting>
  76             In the above example the pointers,
  77             <inlineequation><mml:math><mml:mi mathvariant="italic">v1</mml:mi></mml:math></inlineequation>
  78             through
  79             <inlineequation><mml:math><mml:mi mathvariant="italic">v7</mml:mi></mml:math></inlineequation>,
  80             should point to different
  81             addresses,
  82             since the values stored at these addresses will not be read by
  83             the tesselator until <function>gluTessEndPolygon</function> is called.
  84         </para>
  85     </refsect1>
  86     <refsect1 id="seealso"><title>See Also</title>
  87         <para>
  88             <citerefentry><refentrytitle>gluNewTess</refentrytitle></citerefentry>,
  89             <citerefentry><refentrytitle>gluTessBeginContour</refentrytitle></citerefentry>,
  90             <citerefentry><refentrytitle>gluTessBeginPolygon</refentrytitle></citerefentry>,
  91             <citerefentry><refentrytitle>gluTessCallback</refentrytitle></citerefentry>,
  92             <citerefentry><refentrytitle>gluTessNormal</refentrytitle></citerefentry>,
  93             <citerefentry><refentrytitle>gluTessProperty</refentrytitle></citerefentry>,
  94             <citerefentry><refentrytitle>gluTessVertex</refentrytitle></citerefentry>
  95         </para>
  96     </refsect1>
  97     <refsect1 id="Copyright"><title>Copyright</title>
  98         <para>
  99             Copyright <trademark class="copyright"></trademark> 1991-2006
 100             Silicon Graphics, Inc. This document is licensed under the SGI
 101             Free Software B License. For details, see
 102             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 103         </para>
 104     </refsect1>
 105 </refentry>