
<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>
