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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry id="gluLoadSamplingMatrices">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>gluLoadSamplingMatrices</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>gluLoadSamplingMatrices</refname>
<refpurpose>load NURBS sampling and culling matrices</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>gluLoadSamplingMatrices</function></funcdef>
<paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
<paramdef>const GLfloat * <parameter>model</parameter></paramdef>
<paramdef>const GLfloat * <parameter>perspective</parameter></paramdef>
<paramdef>const GLint * <parameter>view</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>nurb</parameter></term>
<listitem>
<para>
Specifies the NURBS object (created with <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>model</parameter></term>
<listitem>
<para>
Specifies a modelview matrix (as from a <citerefentry><refentrytitle>glGetFloatv</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>perspective</parameter></term>
<listitem>
<para>
Specifies a projection matrix (as from a <citerefentry><refentrytitle>glGetFloatv</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>view</parameter></term>
<listitem>
<para>
Specifies a viewport (as from a <citerefentry><refentrytitle>glGetIntegerv</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>gluLoadSamplingMatrices</function> uses <parameter>model</parameter>, <parameter>perspective</parameter>, and <parameter>view</parameter> to recompute the sampling and culling
matrices stored in <parameter>nurb</parameter>.
The sampling matrix determines how finely a NURBS curve or surface
must be tessellated to satisfy the sampling tolerance (as determined by the
<constant>GLU_SAMPLING_TOLERANCE</constant> property).
The culling matrix is used in deciding if a NURBS curve or surface
should be culled before
rendering (when the <constant>GLU_CULLING</constant> property is turned on).
</para>
<para>
<function>gluLoadSamplingMatrices</function> is necessary only if the <constant>GLU_AUTO_LOAD_MATRIX</constant> property is turned
off (see <citerefentry><refentrytitle>gluNurbsProperty</refentrytitle></citerefentry>).
Although it can be convenient to leave the <constant>GLU_AUTO_LOAD_MATRIX</constant>
property turned on, there can be a performance penalty for doing so.
(A round trip to the GL server is needed to fetch the current values
of the modelview matrix, projection matrix, and viewport.)
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>gluGetNurbsProperty</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>gluNurbsProperty</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
</para>
</refsect1>
</refentry>