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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetProgram">
    <info>
        <copyright>
            <year>2003-2005</year>
            <holder>3Dlabs Inc. Ltd.</holder>
        </copyright>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glGetProgram</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetProgramiv</refname>
        <refpurpose>Returns a parameter from a program object</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
    <funcsynopsis>
        <funcprototype>
        <funcdef>void <function>glGetProgramiv</function></funcdef>
        <paramdef>GLuint <parameter>program</parameter></paramdef>
        <paramdef>GLenum <parameter>pname</parameter></paramdef>
        <paramdef>GLint *<parameter>params</parameter></paramdef>
        </funcprototype>
    </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
    <variablelist>
        <varlistentry>
        <term><parameter>program</parameter></term>
        <listitem>
            <para>Specifies the program object to be
            queried.</para>
        </listitem>
        </varlistentry>
        <varlistentry>
        <term><parameter>pname</parameter></term>
        <listitem>
            <para>Specifies the object parameter. Accepted
            symbolic names are
            <constant>GL_DELETE_STATUS</constant>,
            <constant>GL_LINK_STATUS</constant>,
            <constant>GL_VALIDATE_STATUS</constant>,
            <constant>GL_INFO_LOG_LENGTH</constant>,
            <constant>GL_ATTACHED_SHADERS</constant>,
            <constant>GL_ACTIVE_ATOMIC_COUNTER_BUFFERS</constant>,
            <constant>GL_ACTIVE_ATTRIBUTES</constant>,
            <constant>GL_ACTIVE_ATTRIBUTE_MAX_LENGTH</constant>,
            <constant>GL_ACTIVE_UNIFORMS</constant>,
            <constant>GL_ACTIVE_UNIFORM_BLOCKS</constant>,
            <constant>GL_ACTIVE_UNIFORM_BLOCK_MAX_NAME_LENGTH</constant>,
            <constant>GL_ACTIVE_UNIFORM_MAX_LENGTH</constant>,
            <constant>GL_COMPUTE_WORK_GROUP_SIZE</constant>
            <constant>GL_PROGRAM_BINARY_LENGTH</constant>,
            <constant>GL_TRANSFORM_FEEDBACK_BUFFER_MODE</constant>,
            <constant>GL_TRANSFORM_FEEDBACK_VARYINGS</constant>,
            <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>,
            <constant>GL_GEOMETRY_VERTICES_OUT</constant>,
            <constant>GL_GEOMETRY_INPUT_TYPE</constant>, and
            <constant>GL_GEOMETRY_OUTPUT_TYPE</constant>.</para>
        </listitem>
        </varlistentry>
        <varlistentry>
        <term><parameter>params</parameter></term>
        <listitem>
            <para>Returns the requested object parameter.</para>
        </listitem>
        </varlistentry>
    </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
    <para><function>glGetProgram</function>
    returns in <parameter>params</parameter>
    the value of a parameter for a specific program object. The following parameters are defined:</para>

    <variablelist>
        <varlistentry>
        <term><constant>GL_DELETE_STATUS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns
            <constant>GL_TRUE</constant> if
            <parameter>program</parameter> is currently flagged
            for deletion, and <constant>GL_FALSE</constant>
            otherwise.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_LINK_STATUS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns
            <constant>GL_TRUE</constant> if the last link
            operation on <parameter>program</parameter> was
            successful, and <constant>GL_FALSE</constant>
            otherwise.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_VALIDATE_STATUS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns
            <constant>GL_TRUE</constant> or if the last
            validation operation on
            <parameter>program</parameter> was successful, and
            <constant>GL_FALSE</constant>
            otherwise.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_INFO_LOG_LENGTH</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            number of characters in the information log for
            <parameter>program</parameter> including the null
            termination character (i.e., the size of the
            character buffer required to store the information
            log). If <parameter>program</parameter> has no
            information log, a value of 0 is
            returned.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ATTACHED_SHADERS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            number of shader objects attached to
            <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ACTIVE_ATOMIC_COUNTER_BUFFERS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            number of active attribute atomic counter buffers used by
            <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ACTIVE_ATTRIBUTES</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            number of active attribute variables for
            <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ACTIVE_ATTRIBUTE_MAX_LENGTH</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            length of the longest active attribute name for
            <parameter>program</parameter>, including the null
            termination character (i.e., the size of the
            character buffer required to store the longest
            attribute name). If no active attributes exist, 0 is
            returned.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ACTIVE_UNIFORMS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            number of active uniform variables for
            <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_ACTIVE_UNIFORM_MAX_LENGTH</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            length of the longest active uniform variable name
            for <parameter>program</parameter>, including the
            null termination character (i.e., the size of the
            character buffer required to store the longest
            uniform variable name). If no active uniform
            variables exist, 0 is returned.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_PROGRAM_BINARY_LENGTH</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the
            length of the program binary, in bytes that will be returned by
            a call to <citerefentry><refentrytitle>glGetProgramBinary</refentrytitle></citerefentry>.
            When a progam's <constant>GL_LINK_STATUS</constant> is <constant>GL_FALSE</constant>,
            its program binary length is zero.
            </para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_COMPUTE_WORK_GROUP_SIZE</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns an
            array of three integers containing the local work group size of
            the compute program as specified by its input layout qualifier(s).
            <parameter>program</parameter> must be the name of a program object
            that has been previously linked successfully and contains a binary
            for the compute shader stage.
            </para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_TRANSFORM_FEEDBACK_BUFFER_MODE</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns a symbolic constant
            indicating the buffer mode used when transform feedback is active.
            This may be <constant>GL_SEPARATE_ATTRIBS</constant> or
            <constant>GL_INTERLEAVED_ATTRIBS</constant>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_TRANSFORM_FEEDBACK_VARYINGS</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the number of varying
            variables to capture in transform feedback mode for the program.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the length of the longest
            variable name to be used for transform feedback, including the null-terminator.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_GEOMETRY_VERTICES_OUT</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns the maximum number of vertices
            that the geometry shader in <parameter>program</parameter> will output.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_GEOMETRY_INPUT_TYPE</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns a symbolic constant indicating
            the primitive type accepted as input to the geometry shader contained in
            <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>

        <varlistentry>
        <term><constant>GL_GEOMETRY_OUTPUT_TYPE</constant></term>
        <listitem>
            <para>
            </para>
            <para> <parameter>params</parameter> returns a symbolic constant indicating
            the primitive type that will be output by the geometry shader contained
            in <parameter>program</parameter>.</para>
        </listitem>
        </varlistentry>
    </variablelist>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
    <para>
            <constant>GL_ACTIVE_UNIFORM_BLOCKS</constant> and
            <constant>GL_ACTIVE_UNIFORM_BLOCK_MAX_NAME_LENGTH</constant>
            are available only if the GL version 3.1 or greater.
        </para>
    <para>
        <constant>GL_GEOMETRY_VERTICES_OUT</constant>, <constant>GL_GEOMETRY_INPUT_TYPE</constant>
        and <constant>GL_GEOMETRY_OUTPUT_TYPE</constant> are accepted only if the GL
        version is 3.2 or greater.
    </para>
    <para>
        <constant>GL_COMPUTE_WORK_GROUP_SIZE</constant> is accepted only if the
        GL version is 4.3 or greater.
    </para>

    <para>If an error is generated, no change is made to the
    contents of <parameter>params</parameter>.</para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
    <para><constant>GL_INVALID_VALUE</constant>
    is generated if <parameter>program</parameter>
    is not a value generated by OpenGL.</para>

    <para><constant>GL_INVALID_OPERATION</constant>
    is generated if <parameter>program</parameter>
    does not refer to a program object.</para>

    <para><constant>GL_INVALID_OPERATION</constant> is generated if
    <parameter>pname</parameter> is <constant>GL_GEOMETRY_VERTICES_OUT</constant>,
    <constant>GL_GEOMETRY_INPUT_TYPE</constant>, or <constant>GL_GEOMETRY_OUTPUT_TYPE</constant>,
    and <parameter>program</parameter> does not contain a geometry shader.</para>

    <para><constant>GL_INVALID_ENUM</constant>
    is generated if <parameter>pname</parameter>
    is not an accepted value.</para>

    <para><constant>GL_INVALID_OPERATION</constant> is generated if <parameter>pname</parameter>
    is <constant>GL_COMPUTE_WORK_GROUP_SIZE</constant> and <parameter>program</parameter>
    does not contain a binary for the compute shader stage.</para>

    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
    <para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
    with argument <parameter>program</parameter></para>

    <para><citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry>
    with argument <parameter>program</parameter></para>

    <para><citerefentry><refentrytitle>glGetAttachedShaders</refentrytitle></citerefentry>
    with argument <parameter>program</parameter></para>

    <para><citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry>
    with argument <parameter>program</parameter></para>

    <para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry>
    <parameter/></para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
    <para><citerefentry><refentrytitle>glAttachShader</refentrytitle></citerefentry>,
    <citerefentry><refentrytitle>glCreateProgram</refentrytitle></citerefentry>,
    <citerefentry><refentrytitle>glDeleteProgram</refentrytitle></citerefentry>,
    <citerefentry><refentrytitle>glGetShader</refentrytitle></citerefentry>,
    <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>,
    <citerefentry><refentrytitle>glValidateProgram</refentrytitle></citerefentry></para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2003-2005 3Dlabs Inc. Ltd.
            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>
