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+<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>gluTessNormal</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="gluTessNormal"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gluTessNormal — specify a normal for a polygon</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">gluTessNormal</b>(</code></td><td>GLUtesselator* </td><td><var class="pdparam">tess</var>, </td></tr><tr><td> </td><td>GLdouble </td><td><var class="pdparam">valueX</var>, </td></tr><tr><td> </td><td>GLdouble </td><td><var class="pdparam">valueY</var>, </td></tr><tr><td> </td><td>GLdouble </td><td><var class="pdparam">valueZ</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>tess</code></em></span></dt><dd><p>
+ Specifies the tessellation object (created with <a class="citerefentry" href="gluNewTess.xml"><span class="citerefentry"><span class="refentrytitle">gluNewTess</span></span></a>).
+ </p></dd><dt><span class="term"><em class="parameter"><code>valueX</code></em></span></dt><dd><p>
+ Specifies the first component of the normal.
+ </p></dd><dt><span class="term"><em class="parameter"><code>valueY</code></em></span></dt><dd><p>
+ Specifies the second component of the normal.
+ </p></dd><dt><span class="term"><em class="parameter"><code>valueZ</code></em></span></dt><dd><p>
+ Specifies the third component of the normal.
+ </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
+ <code class="function">gluTessNormal</code> describes a normal for a polygon that the program is defining.
+ All input data will be projected onto a plane perpendicular to one of
+ the three coordinate axes before tessellation and all output triangles
+ will be oriented CCW with
+ respect to the normal (CW orientation can be obtained by reversing the
+ sign of the supplied normal). For example, if you know that all polygons
+ lie in the x-y plane, call <code class="function">gluTessNormal</code>(tess, 0.0, 0.0, 1.0)
+ before rendering any polygons.
+ </p><p>
+ If the supplied normal is (0.0, 0.0, 0.0) (the initial value), the normal is
+ determined as follows. The direction of the normal, up to its sign, is
+ found by fitting a plane to the vertices, without regard to how the
+ vertices are connected. It is expected that the input data lies approximately
+ in the plane; otherwise, projection perpendicular to one of the three
+ coordinate axes may substantially change the geometry. The sign of the
+ normal is chosen so that the sum of the signed areas of all input
+ contours is nonnegative (where a CCW contour has positive area).
+ </p><p>
+ The supplied normal persists until it is changed by another call to
+ <code class="function">gluTessNormal</code>.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
+ <a class="citerefentry" href="gluTessBeginPolygon.xml"><span class="citerefentry"><span class="refentrytitle">gluTessBeginPolygon</span></span></a>,
+ <a class="citerefentry" href="gluTessEndPolygon.xml"><span class="citerefentry"><span class="refentrytitle">gluTessEndPolygon</span></span></a>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
+ Copyright <span class="trademark"></span>© 1991-2006
+ Silicon Graphics, Inc. This document is licensed under the SGI
+ Free Software B License. For details, see
+ <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
+ </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blobdiff