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<refentry id="glGetProgramResourceName">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2012</year>
                <holder>Khronos Group</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetProgramResourceName</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetProgramResourceName</refname>
        <refpurpose>query the name of an indexed resource within a program</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetProgramResourceName</function></funcdef>
                <paramdef>GLuint <parameter>program</parameter></paramdef>
                <paramdef>GLenum <parameter>programInterface</parameter></paramdef>
                <paramdef>GLuint <parameter>index</parameter></paramdef>
                <paramdef>GLsizei <parameter>bufSize</parameter></paramdef>
                <paramdef>GLsizei * <parameter>length</parameter></paramdef>
                <paramdef>char * <parameter>name</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>program</parameter></term>
            <listitem>
                <para>
                    The name of a program object whose resources to query.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>programInterface</parameter></term>
            <listitem>
                <para>
                    A token identifying the interface within <parameter>program</parameter> containing the indexed resource.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>index</parameter></term>
            <listitem>
                <para>
                    The index of the resource within <parameter>programInterface</parameter> of <parameter>program</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>bufSize</parameter></term>
            <listitem>
                <para>
                    The size of the character array whose address is given by <parameter>name</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>length</parameter></term>
            <listitem>
                <para>
                    The address of a variable which will receive the length of the resource name.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>name</parameter></term>
            <listitem>
                <para>
                    The address of a character array into which will be written the name of the resource.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetProgramResourceName</function> retrieves the name string
            assigned to the single active resource with an index of <parameter>index</parameter>
            in the interface <parameter>programInterface</parameter> of program object
            <parameter>program</parameter>. <parameter>index</parameter> must be less than
            the number of entries in the active resource list for <parameter>programInterface</parameter>.
        </para>
        <para>
            <parameter>program</parameter> must be the name of an existing program object. <parameter>programInterface</parameter>
            is the name of the interface within <parameter>program</parameter> which contains the resource and must be one of the following
            values:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_UNIFORM</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active uniforms within <parameter>program</parameter>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_UNIFORM_BLOCK</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active uniform blocks within <parameter>program</parameter>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_PROGRAM_INPUT</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active input variables used by the first shader stage of <parameter>program</parameter>.
                        If <parameter>program</parameter> contains multiple shader stages then input variables from any stage other than the first
                        will not be enumerated.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_PROGRAM_OUTPUT</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active output variables produced by the last shader stage of <parameter>program</parameter>.
                        If <parameter>program</parameter> contains multiple shader stages then output variables from any stage other than the last
                        will not be enumerated.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_VERTEX_SUBROUTINE</constant></term>,
                <term><constant>GL_TESS_CONTROL_SUBROUTINE</constant></term>,
                <term><constant>GL_TESS_EVALUATION_SUBROUTINE</constant></term>,
                <term><constant>GL_GEOMETRY_SUBROUTINE</constant></term>,
                <term><constant>GL_FRAGMENT_SUBROUTINE</constant></term>,
                <term><constant>GL_COMPUTE_SUBROUTINE</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active subroutines for the vertex, tessellation control, tessellation evaluation,
                        geometry, fragment and compute shader stages of <parameter>program</parameter>, respectively.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_VERTEX_SUBROUTINE_UNIFORM</constant></term>,
                <term><constant>GL_TESS_CONTROL_SUBROUTINE_UNIFORM</constant></term>,
                <term><constant>GL_TESS_EVALUATION_SUBROUTINE_UNIFORM</constant></term>,
                <term><constant>GL_GEOMETRY_SUBROUTINE_UNIFORM</constant></term>,
                <term><constant>GL_FRAGMENT_SUBROUTINE_UNIFORM</constant></term>,
                <term><constant>GL_COMPUTE_SUBROUTINE_UNIFORM</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active subroutine uniform variables used by the vertex, tessellation control, tessellation evaluation,
                        geometry, fragment and compute shader stages of <parameter>program</parameter>, respectively.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_TRANSFORM_FEEDBACK_VARYING</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of output variables from the last non-fragment stage of <parameter>program</parameter> that would be
                        captured if transform feedback were active.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BUFFER_VARIABLE</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active buffer variables used by <parameter>program</parameter>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_SHADER_STORAGE_BLOCK</constant></term>
                <listitem>
                    <para>
                        The query is targeted at the set of active shader storage blocks used by <parameter>program</parameter>.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
            The name string assigned to the active resource identified by <parameter>index</parameter> is
            returned as a null-terminated string in the character array whose address is given 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 NULL, 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>.  If the length of the name string
            <emphasis>including the null terminator</emphasis> is greater than <parameter>bufSize</parameter>, the first
            <parameter>bufSize</parameter>-1 characters of the name string will be written to <parameter>name</parameter>,
            followed by a null terminator.  If <parameter>bufSize</parameter> is zero, no error will be
            generated but no characters will be written to <parameter>name</parameter>.  The length of the
            longest name string for <parameter>programInterface</parameter>>, including a null terminator,
            can be queried by calling <citerefentry><refentrytitle>glGetProgramInterface</refentrytitle></citerefentry> with a <parameter>pname</parameter> of
            <constant>GL_MAX_NAME_LENGTH</constant>.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>programInterface</parameter>
            is not one of the accepted interface types.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>progam</parameter> is not
            the name of an existing program.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater
            than or equal to the number of entries in the active resource list for
            <parameter>programInterface</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>programInterface</parameter> is
            <constant>GL_ATOMIC_COUNTER_BUFFER</constant> or <constant>GL_TRANSFORM_FEEDBACK_BUFFER</constant>, since active atomic
            counter and transform feedback buffer resources are not assigned name strings.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glGetProgramResourceIndex</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetGetProgramResource</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetProgramResourceLocation</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetProgramResourceLocationIndex</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2012 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>
