
<refentry id="gluPartialDisk">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>gluPartialDisk</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>gluPartialDisk</refname>
        <refpurpose>draw an arc of a disk</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>gluPartialDisk</function></funcdef>
                <paramdef>GLUquadric* <parameter>quad</parameter></paramdef>
                <paramdef>GLdouble <parameter>inner</parameter></paramdef>
                <paramdef>GLdouble <parameter>outer</parameter></paramdef>
                <paramdef>GLint <parameter>slices</parameter></paramdef>
                <paramdef>GLint <parameter>loops</parameter></paramdef>
                <paramdef>GLdouble <parameter>start</parameter></paramdef>
                <paramdef>GLdouble <parameter>sweep</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <!-- eqn: ignoring delim $$ -->
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>quad</parameter></term>
            <listitem>
                <para>
                    Specifies a quadrics object (created with <citerefentry><refentrytitle>gluNewQuadric</refentrytitle></citerefentry>).
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>inner</parameter></term>
            <listitem>
                <para>
                    Specifies the inner radius of the partial disk (can be 0).
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>outer</parameter></term>
            <listitem>
                <para>
                    Specifies the outer radius of the partial disk.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>slices</parameter></term>
            <listitem>
                <para>
                    Specifies the number of subdivisions around the <emphasis>z</emphasis> axis.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>loops</parameter></term>
            <listitem>
                <para>
                    Specifies the number of concentric rings about the origin into which
                    the partial disk is subdivided.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>start</parameter></term>
            <listitem>
                <para>
                    Specifies the starting angle, in degrees, of the disk portion.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>sweep</parameter></term>
            <listitem>
                <para>
                    Specifies the sweep angle, in degrees, of the disk portion.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>gluPartialDisk</function> renders a partial disk on the 
            <inlineequation><mml:math>
                <!-- eqn: z  =  0:-->
                <mml:mrow>
                    <mml:mi mathvariant="italic">z</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mn>0</mml:mn>
                </mml:mrow>
            </mml:math></inlineequation>
            plane. A partial disk is 
            similar to a full disk, except that only the subset of the disk from
            <parameter>start</parameter> through <parameter>start</parameter> + <parameter>sweep</parameter> is included (where 0 degrees is along the 
            +\f2y\f axis,
            90 degrees along the +<emphasis>x</emphasis> axis, 180 degrees along the \-<emphasis>y</emphasis> axis, and 
            270 degrees along the \-<emphasis>x</emphasis> axis).
        </para>
        <para>
            The partial disk has a radius of 
            <parameter>outer</parameter> and contains a concentric circular hole with a radius 
            of <parameter>inner</parameter>. If <parameter>inner</parameter> is 0, then no hole is generated. The partial disk is
            subdivided around the <emphasis>z</emphasis> axis into slices (like pizza slices) and also
            about the <emphasis>z</emphasis> axis into rings 
            (as specified by <parameter>slices</parameter> and <parameter>loops</parameter>, respectively).
        </para>
        <para>
            With respect to orientation, the +<emphasis>z</emphasis> 
            side of the partial disk is considered to 
            be outside (see <citerefentry><refentrytitle>gluQuadricOrientation</refentrytitle></citerefentry>).
            This means that if the 
            orientation is set to <constant>GLU_OUTSIDE</constant>, then any normals generated 
            point along the +<emphasis>z</emphasis> axis. Otherwise, they point along the \-<emphasis>z</emphasis> 
            axis.
        </para>
        <para>
            If texturing is turned on (with <citerefentry><refentrytitle>gluQuadricTexture</refentrytitle></citerefentry>), texture
            coordinates are generated
            linearly such that where 
            <inlineequation><mml:math>
                <!-- eqn: r  =  outer:-->
                <mml:mrow>
                    <mml:mi mathvariant="italic">r</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mi mathvariant="italic">outer</mml:mi>
                </mml:mrow>
            </mml:math></inlineequation>,
            the value at (<emphasis>r</emphasis>, 0, 0) is 
            (1.0, 0.5), at (0, <emphasis>r</emphasis>, 0) it is (0.5, 1.0), at (\-<emphasis>r</emphasis>, 0, 0) 
            it is (0.0, 0.5), and 
            at (0, \-<emphasis>r</emphasis>, 0) it is (0.5, 0.0).
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>gluCylinder</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluDisk</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluNewQuadric</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluQuadricOrientation</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluQuadricTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>gluSphere</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>
