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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetUniformSubroutine">
    <info>
        <copyright>
            <year>2010-2014</year>
            <holder>Khronos Group.</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glGetUniformSubroutine</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetUniformSubroutine</refname>
        <refpurpose>retrieve the value of a subroutine uniform of a given shader stage of the current program</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetUniformSubroutineuiv</function></funcdef>
                <paramdef>GLenum <parameter>shadertype</parameter></paramdef>
                <paramdef>GLint <parameter>location</parameter></paramdef>
                <paramdef>GLuint *<parameter>values</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>shadertype</parameter></term>
            <listitem>
                <para>
                    Specifies the shader stage from which to query for subroutine uniform index.
                    <parameter>shadertype</parameter>
                    must be one of <constant>GL_VERTEX_SHADER</constant>, <constant>GL_TESS_CONTROL_SHADER</constant>,
                    <constant>GL_TESS_EVALUATION_SHADER</constant>, <constant>GL_GEOMETRY_SHADER</constant> or
                    <constant>GL_FRAGMENT_SHADER</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>location</parameter></term>
            <listitem>
                <para>
                    Specifies the location of the subroutine uniform.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>values</parameter></term>
            <listitem>
                <para>
                    Specifies the address of a variable to receive the value or values of the subroutine uniform.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glGetUniformSubroutine</function> retrieves the value of the subroutine uniform at location
            <parameter>location</parameter> for shader stage <parameter>shadertype</parameter> of the current
            program. <parameter>location</parameter> must be less than the value of
            <constant>GL_ACTIVE_SUBROUTINE_UNIFORM_LOCATIONS</constant> for the shader currently in use at
            shader stage <parameter>shadertype</parameter>. The value of the subroutine uniform is returned in
            <parameter>values</parameter>.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>shadertype</parameter> is not one of the accepted values.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>location</parameter> is greater than or equal to
            the value of <constant>GL_ACTIVE_SUBROUTINE_UNIFORM_LOCATIONS</constant> for the shader currently in use at
            shader stage <parameter>shadertype</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if no program is active.
        </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="apifunchead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry><function>glGetUniformSubroutineuiv</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='40']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetActiveSubroutineUniform</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetActiveSubroutineUniformName</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2010-2014 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>
