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<refentry id="glGetActiveSubroutineName">
    <refentryinfo>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group.</holder>
        </copyright>
    </refentryinfo>
    <refmeta>
        <refentrytitle>glGetActiveSubroutineName</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetActiveSubroutineName</refname>
        <refpurpose>query the name of an active shader subroutine</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetActiveSubroutineName</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 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 the subroutine name.
                </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 which is to receive the length of the shader subroutine uniform name.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>name</parameter></term>
            <listitem>
                <para>
                    Specifies the address of an array into which the name of the shader subroutine uniform will be written.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetActiveSubroutineName</function> queries the name of an active shader subroutine uniform from the
            program object given in <parameter>program</parameter>. <parameter>index</parameter> specifies the index of
            the shader subroutine uniform within the shader stage given by <parameter>stage</parameter>, and must between
            zero and the value of <constant>GL_ACTIVE_SUBROUTINES</constant> minus one for the shader stage.
        </para>
        <para>
            The name of the selected subroutine is returned as a null-terminated string in <parameter>name</parameter>. The
            actual number of characters written into <parameter>name</parameter>, not including the null-terminator, is
            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 given in <parameter>bufsize</parameter>.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <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 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetProgramStage</refentrytitle></citerefentry> with argument <constant>GL_ACTIVE_SUBROUTINE_UNIFORM_MAX_LENGTH</constant>
        </para>
    </refsect1>
    <refsect1 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 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 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.
            <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
        </para>
    </refsect1>
</refentry>
