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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetActiveSubroutineUniformName">
    <info>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group.</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glGetActiveSubroutineUniformName</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetActiveSubroutineUniformName</refname>
        <refpurpose>query the name of an active shader subroutine uniform</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetActiveSubroutineUniformName</function></funcdef>
                <paramdef>GLuint <parameter>program</parameter></paramdef>
                <paramdef>GLenum <parameter>shadertype</parameter></paramdef>
                <paramdef>GLuint <parameter>index</parameter></paramdef>
                <paramdef>GLsizei <parameter>bufsize</parameter></paramdef>
                <paramdef>GLsizei *<parameter>length</parameter></paramdef>
                <paramdef>GLchar *<parameter>name</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>program</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the program containing the subroutine.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>shadertype</parameter></term>
            <listitem>
                <para>
                    Specifies the shader stage from which to query for the subroutine parameter. <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>index</parameter></term>
            <listitem>
                <para>
                    Specifies the index of the shader subroutine uniform.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>bufsize</parameter></term>
            <listitem>
                <para>
                    Specifies the size of the buffer whose address is given in <parameter>name</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>length</parameter></term>
            <listitem>
                <para>
                    Specifies the address of a variable into which is written the number of characters copied into <parameter>name</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>name</parameter></term>
            <listitem>
                <para>
                    Specifies the address of a buffer that will receive the name of the specified shader subroutine uniform.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glGetActiveSubroutineUniformName</function> retrieves the name of an active shader subroutine uniform.
            <parameter>program</parameter> contains the name of the program containing the uniform. <parameter>shadertype</parameter>
            specifies the stage for which which the uniform location, given by <parameter>index</parameter>, is valid. <parameter>index</parameter>
            must be between zero and the value of <constant>GL_ACTIVE_SUBROUTINE_UNIFORMS</constant> minus one for the
            shader stage.
        </para>
        <para>
            The uniform name is returned as a null-terminated string in <parameter>name</parameter>. The actual number of characters
            written into <parameter>name</parameter>, excluding the null terminator is returned in <parameter>length</parameter>.
            If <parameter>length</parameter> is <constant>NULL</constant>, no length is returned. The maximum number of characters
            that may be written into <parameter>name</parameter>, including the null terminator, is specified by <parameter>bufsize</parameter>.
            The length of the longest subroutine uniform name in <parameter>program</parameter> and <parameter>shadertype</parameter> is given
            by the value of <constant>GL_ACTIVE_SUBROUTINE_UNIFORM_MAX_LENGTH</constant>, which can be queried with
            <citerefentry><refentrytitle>glGetProgramStage</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>shadertype</parameter> or <parameter>pname</parameter>
            is not one of the accepted values.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater than or equal to
            the value of <constant>GL_ACTIVE_SUBROUTINES</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>program</parameter> is not the name of an
            existing program object.
        </para>
    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetProgramStage</refentrytitle></citerefentry> with argument <constant>GL_ACTIVE_SUBROUTINE_UNIFORMS</constant>
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glGetSubroutineIndex</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetActiveSubroutineUniform</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetProgramStage</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2010-2013 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>
