
<refentry id="gluPwlCurve">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>gluPwlCurve</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>gluPwlCurve</refname>
        <refpurpose>describe a piecewise linear NURBS trimming curve</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>gluPwlCurve</function></funcdef>
                <paramdef>GLUnurbs* <parameter>nurb</parameter></paramdef>
                <paramdef>GLint <parameter>count</parameter></paramdef>
                <paramdef>GLfloat* <parameter>data</parameter></paramdef>
                <paramdef>GLint <parameter>stride</parameter></paramdef>
                <paramdef>GLenum <parameter>type</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>count</parameter></term>
            <listitem>
                <para>
                    Specifies the number of points on the curve.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Specifies an array containing the curve points.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>stride</parameter></term>
            <listitem>
                <para>
                    Specifies the offset (a number of single-precision floating-point values)
                    between points on the curve.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>type</parameter></term>
            <listitem>
                <para>
                    Specifies the type of curve.
                    Must be either <constant>GLU_MAP1_TRIM_2</constant> or <constant>GLU_MAP1_TRIM_3</constant>.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>gluPwlCurve</function> describes a piecewise linear trimming curve for a NURBS surface.
            A piecewise linear curve consists of a list of 
            coordinates of points in the parameter space for the
            NURBS surface to be trimmed. These points are connected
            with line segments to form a curve. If the curve is
            an approximation to a curve that is not piecewise linear, 
            the points should be close enough in parameter space that the 
            resulting path appears curved at the resolution used in the application.
        </para>
        <para>
            If <parameter>type</parameter> is
            <constant>GLU_MAP1_TRIM_2</constant>, then it describes a curve in two-dimensional (<emphasis>u</emphasis> 
            and <emphasis>v</emphasis>) parameter space. If it is <constant>GLU_MAP1_TRIM_3</constant>, then it
            describes a curve in two-dimensional homogeneous (<emphasis>u</emphasis>, <emphasis>v</emphasis>,
            and <emphasis>w</emphasis>) parameter space. 
            See the <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry> reference page for more information 
            about trimming curves. 
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            To describe a trim curve that closely follows the contours of a NURBS 
            surface, call <citerefentry><refentrytitle>gluNurbsCurve</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>gluBeginCurve</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluBeginTrim</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluNewNurbsRenderer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluNurbsCurve</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>
