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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glDepthRange">
    <info>
        <copyright>
            <year>1991-2006</year>
            <holder>Silicon Graphics, Inc.</holder>
        </copyright>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glDepthRange</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glDepthRange</refname>
        <refpurpose>specify mapping of depth values from normalized device coordinates to window coordinates</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glDepthRange</function></funcdef>
                <paramdef>GLdouble <parameter>nearVal</parameter></paramdef>
                <paramdef>GLdouble <parameter>farVal</parameter></paramdef>
            </funcprototype>
            <funcprototype>
                <funcdef>void <function>glDepthRangef</function></funcdef>
                <paramdef>GLfloat <parameter>nearVal</parameter></paramdef>
                <paramdef>GLfloat <parameter>farVal</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>nearVal</parameter></term>
            <listitem>
                <para>
                    Specifies the mapping of the near clipping plane to window coordinates.
                    The initial value is 0.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>farVal</parameter></term>
            <listitem>
                <para>
                    Specifies the mapping of the far clipping plane to window coordinates.
                    The initial value is 1.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            After clipping and division by <emphasis>w</emphasis>,
            depth coordinates range from
            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <!-- eqn: -1: -->
                <mml:mn>-1</mml:mn>
            </mml:math></inlineequation>
            to 1,
            corresponding to the near and far clipping planes.
            <function>glDepthRange</function> specifies a linear mapping of the normalized depth coordinates
            in this range to window depth coordinates.
            Regardless of the actual depth buffer implementation,
            window coordinate depth values are treated as though they range
            from 0 through 1 (like color components).
            Thus,
            the values accepted by <function>glDepthRange</function> are both clamped to this range
            before they are accepted.
        </para>
        <para>
            The setting of (0,1) maps the near plane to 0 and
            the far plane to 1.
            With this mapping,
            the depth buffer range is fully utilized.
        </para>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <para>
            It is not necessary that <parameter>nearVal</parameter> be less than <parameter>farVal</parameter>.
            Reverse mappings such as
            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <!-- eqn: nearVal  =  1: -->
                <mml:mrow>
                    <mml:mi mathvariant="italic">nearVal</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mn>1</mml:mn>
                </mml:mrow>
            </mml:math></inlineequation>,
            and
            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                <!-- eqn: farVal  =  0: -->
                <mml:mrow>
                    <mml:mi mathvariant="italic">farVal</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mn>0</mml:mn>
                </mml:mrow>
            </mml:math></inlineequation>
            are acceptable.
        </para>
        <para>
            The type of the <parameter>nearVal</parameter> and
            <parameter>farVal</parameter> parameters was changed from
            GLclampf to GLfloat for <function>glDepthRangef</function>
            and from GLclampd to GLdouble for
            <function>glDepthRange</function>. This change is
            transparent to user code and is described in detail on the
            <citerefentry><refentrytitle>removedTypes</refentrytitle></citerefentry>
            page.
        </para>
    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DEPTH_RANGE</constant>
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glPolygonOffset</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glViewport</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>removedTypes</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 1991-2006 Silicon Graphics, Inc.
            Copyright <trademark class="copyright"/> 2010-2013 Khronos Group.
            This document is licensed under the SGI Free Software B License.
            For details, see
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</link>.
        </para>
    </refsect1>
</refentry>
