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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="gl_FragDepth">
    <info>
        <copyright>
            <year>2011-2014</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>gl_FragDepth</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>gl_FragDepth</refname>
        <refpurpose>establishes a depth value for the current fragment</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title>Declaration</title>
        <fieldsynopsis>
            <modifier>out</modifier>
            <type>float</type>
            <varname>gl_FragDepth</varname>
        </fieldsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            Available only in the fragment language, <varname>gl_FragDepth</varname> is an output variable
            that is used to establish the depth value for the current fragment. If depth buffering is enabled
            and no shader writes to <varname>gl_FragDepth</varname>, then the fixed function value for
            depth will be used (this value is contained in the z component of <citerefentry><refentrytitle>gl_FragCoord</refentrytitle></citerefentry>)
            otherwise, the value written to <varname>gl_FragDepth</varname> is used.
            If a shader statically assigns to <varname>gl_FragDepth</varname>, then the value of the fragment's depth
            may be undefined for executions of the shader that take that path. That is, if the set of linked fragment
            shaders statically contain a write to <varname>gl_FragDepth</varname>, then it is responsible for always
            writing it.
        </para>
    </refsect1>
    <refsect1 xml:id="versions"><title>Version Support</title>
        <informaltable>
            <tgroup cols="13" align="left">
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="varhead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry>gl_FragDepth</entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='11']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>gl_FragCoord</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2011-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
        </para>
    </refsect1>
</refentry>
