<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>

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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glSamplerParameter">
    <info>
        <copyright>
            <year>2010-2014</year>
            <holder>KhronosGroup</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glSamplerParameter</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glSamplerParameter</refname>
        <refpurpose>set sampler parameters</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glSamplerParameterf</function></funcdef>
                <paramdef>GLuint <parameter>sampler</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLfloat <parameter>param</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glSamplerParameteri</function></funcdef>
                <paramdef>GLuint <parameter>sampler</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint <parameter>param</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
            <!-- Vector commands -->
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glSamplerParameterfv</function></funcdef>
                <paramdef>GLuint <parameter>sampler</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>const GLfloat * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glSamplerParameteriv</function></funcdef>
                <paramdef>GLuint <parameter>sampler</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>const GLint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>sampler</parameter></term>
            <listitem>
                <para>
                    Specifies the sampler object whose parameter to modify.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>pname</parameter></term>
            <listitem>
                <para>
                    Specifies the symbolic name of a single-valued sampler parameter.
                    <parameter>pname</parameter> can be one of the following:
                    <constant>GL_TEXTURE_WRAP_S</constant>,
                    <constant>GL_TEXTURE_WRAP_T</constant>,
                    <constant>GL_TEXTURE_WRAP_R</constant>,
                    <constant>GL_TEXTURE_MIN_FILTER</constant>,
                    <constant>GL_TEXTURE_MAG_FILTER</constant>,
                    <constant>GL_TEXTURE_MIN_LOD</constant>,
                    <constant>GL_TEXTURE_MAX_LOD</constant>,
                    <constant>GL_TEXTURE_COMPARE_MODE</constant>, or
                    <constant>GL_TEXTURE_COMPARE_FUNC</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>param</parameter></term>
            <listitem>
                <para>
                    For the scalar commands, specifies the value of
                    <parameter>pname</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>params</parameter></term>
            <listitem>
                <para>
                    For the vector commands
                    (<function>glSamplerParameter*v</function>), specifies a
                    pointer to an array where the value or values of
                    <parameter>pname</parameter> are stored.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glSamplerParameter</function> assigns the value or values in <parameter>params</parameter> to the sampler parameter
            specified as <parameter>pname</parameter>.
            <parameter>sampler</parameter> specifies the sampler object to be modified, and must be the name of a sampler object previously
            returned from a call to <citerefentry><refentrytitle>glGenSamplers</refentrytitle></citerefentry>.
            The following symbols are accepted in <parameter>pname</parameter>:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_MIN_FILTER</constant></term>
                <listitem>
                    <para>
                        The texture minifying function is used whenever the pixel being textured
                        maps to an area greater than one texture element.
                        There are six defined minifying functions.
                        Two of them use the nearest one or nearest four texture elements
                        to compute the texture value.
                        The other four use mipmaps.
                    </para>
                    <para>
                        A mipmap is an ordered set of arrays representing the same image
                        at progressively lower resolutions.
                        If the texture has dimensions
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 2 sup n  times  2 sup m: -->
                            <mml:mrow>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">n</mml:mi>
                                </mml:msup>
                                <mml:mo>&times;</mml:mo>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">m</mml:mi>
                                </mml:msup>
                            </mml:mrow>
                        </mml:math></inlineequation>,
                        there are
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: max ( n, m ) + 1: -->
                            <mml:mrow>
                                <mml:mrow>
                                    <mml:mi mathvariant="italic">max</mml:mi>
                                    <mml:mo>&af;</mml:mo>
                                    <mml:mfenced open="(" close=")">
                                        <mml:mi mathvariant="italic">n</mml:mi>
                                        <mml:mi mathvariant="italic">m</mml:mi>
                                    </mml:mfenced>
                                </mml:mrow>
                                <mml:mo>+</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        mipmaps.
                        The first mipmap is the original texture,
                        with dimensions
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 2 sup n  times  2 sup m: -->
                            <mml:mrow>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">n</mml:mi>
                                </mml:msup>
                                <mml:mo>&times;</mml:mo>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">m</mml:mi>
                                </mml:msup>
                            </mml:mrow>
                        </mml:math></inlineequation>.
                        Each subsequent mipmap has dimensions
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 2 sup { k - 1 }  times  2 sup { l - 1 }: -->
                            <mml:mrow>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mfenced open="" close="">
                                    <mml:mrow>
                                        <mml:mi mathvariant="italic">k</mml:mi>
                                        <mml:mo>-</mml:mo>
                                        <mml:mn>1</mml:mn>
                                    </mml:mrow>
                                </mml:mfenced>
                                </mml:msup>
                                <mml:mo>&times;</mml:mo>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mfenced open="" close="">
                                    <mml:mrow>
                                        <mml:mi mathvariant="italic">l</mml:mi>
                                        <mml:mo>-</mml:mo>
                                        <mml:mn>1</mml:mn>
                                    </mml:mrow>
                                </mml:mfenced>
                                </mml:msup>
                            </mml:mrow>
                        </mml:math></inlineequation>,
                        where
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 2 sup k  times  2 sup l: -->
                            <mml:mrow>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">k</mml:mi>
                                </mml:msup>
                                <mml:mo>&times;</mml:mo>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mi mathvariant="italic">l</mml:mi>
                                </mml:msup>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        are the dimensions of the previous mipmap,
                        until either
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: k  =  0: -->
                            <mml:mrow>
                                <mml:mi mathvariant="italic">k</mml:mi>
                                <mml:mo>=</mml:mo>
                                <mml:mn>0</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        or
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: l = 0: -->
                            <mml:mrow>
                                <mml:mi mathvariant="italic">l</mml:mi>
                                <mml:mo>=</mml:mo>
                                <mml:mn>0</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>.
                        At that point,
                        subsequent mipmaps have dimension
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 1  times  2 sup { l - 1 }: -->
                            <mml:mrow>
                                <mml:mn>1</mml:mn>
                                <mml:mo>&times;</mml:mo>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mfenced open="" close="">
                                    <mml:mrow>
                                        <mml:mi mathvariant="italic">l</mml:mi>
                                        <mml:mo>-</mml:mo>
                                        <mml:mn>1</mml:mn>
                                    </mml:mrow>
                                </mml:mfenced>
                                </mml:msup>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        or
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 2 sup { k - 1}  times  1: -->
                            <mml:mrow>
                                <mml:msup><mml:mn>2</mml:mn>
                                <mml:mfenced open="" close="">
                                    <mml:mrow>
                                        <mml:mi mathvariant="italic">k</mml:mi>
                                        <mml:mo>-</mml:mo>
                                        <mml:mn>1</mml:mn>
                                    </mml:mrow>
                                </mml:mfenced>
                                </mml:msup>
                                <mml:mo>&times;</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        until the final mipmap,
                        which has dimension
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 1  times  1: -->
                            <mml:mrow>
                                <mml:mn>1</mml:mn>
                                <mml:mo>&times;</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>.
                        To define the mipmaps, call <citerefentry><refentrytitle>glTexStorage2D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
                         <citerefentry><refentrytitle>glTexStorage2D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
                        or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>
                        with the <emphasis>level</emphasis> argument indicating the order of the mipmaps.
                        Level 0 is the original texture;
                        level
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: max ( n, m ): -->
                            <mml:mrow>
                                <mml:mi mathvariant="italic">max</mml:mi>
                                <mml:mo>&af;</mml:mo>
                                <mml:mfenced open="(" close=")">
                                    <mml:mi mathvariant="italic">n</mml:mi>
                                    <mml:mi mathvariant="italic">m</mml:mi>
                                </mml:mfenced>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        is the final
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 1  times  1: -->
                            <mml:mrow>
                                <mml:mn>1</mml:mn>
                                <mml:mo>&times;</mml:mo>
                                <mml:mn>1</mml:mn>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        mipmap.
                    </para>
                    <para>
                        <parameter>params</parameter> supplies a function for minifying the texture as one of the
                        following:
                        <variablelist>
                            <varlistentry>
                                <term><constant>GL_NEAREST</constant></term>
                                <listitem>
                                    <para>
                                        Returns the value of the texture element that is nearest
                                        (in Manhattan distance)
                                        to the center of the pixel being textured.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_LINEAR</constant></term>
                                <listitem>
                                    <para>
                                        Returns the weighted average of the four texture elements
                                        that are closest to the center of the pixel being textured.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_NEAREST_MIPMAP_NEAREST</constant></term>
                                <listitem>
                                    <para>
                                        Chooses the mipmap that most closely matches the size of the pixel
                                        being textured and uses the <constant>GL_NEAREST</constant> criterion
                                        (the texture element nearest to the center of the pixel)
                                        to produce a texture value.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_LINEAR_MIPMAP_NEAREST</constant></term>
                                <listitem>
                                    <para>
                                        Chooses the mipmap that most closely matches the size of the pixel
                                        being textured and uses the <constant>GL_LINEAR</constant> criterion
                                        (a weighted average of the four texture elements that are closest
                                        to the center of the pixel)
                                        to produce a texture value.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_NEAREST_MIPMAP_LINEAR</constant></term>
                                <listitem>
                                    <para>
                                        Chooses the two mipmaps that most closely match the size of the pixel
                                        being textured and uses the <constant>GL_NEAREST</constant> criterion
                                        (the texture element nearest to the center of the pixel)
                                        to produce a texture value from each mipmap.
                                        The final texture value is a weighted average of those two values.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_LINEAR_MIPMAP_LINEAR</constant></term>
                                <listitem>
                                    <para>
                                        Chooses the two mipmaps that most closely match the size of the pixel
                                        being textured and uses the <constant>GL_LINEAR</constant> criterion
                                        (a weighted average of the four texture elements that are closest
                                        to the center of the pixel)
                                        to produce a texture value from each mipmap.
                                        The final texture value is a weighted average of those two values.
                                    </para>
                                </listitem>
                            </varlistentry>
                        </variablelist>
                    </para>
                    <para>
                        As more texture elements are sampled in the minification process,
                        fewer aliasing artifacts will be apparent.
                        While the <constant>GL_NEAREST</constant> and <constant>GL_LINEAR</constant> minification functions can be
                        faster than the other four,
                        they sample only one or four texture elements to determine the texture value
                        of the pixel being rendered and can produce moire patterns
                        or ragged transitions.
                        The initial value of <constant>GL_TEXTURE_MIN_FILTER</constant> is
                        <constant>GL_NEAREST_MIPMAP_LINEAR</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_TEXTURE_MAG_FILTER</constant></term>
                <listitem>
                    <para>
                        The texture magnification function is used when the pixel being textured
                        maps to an area less than or equal to one texture element.
                        It sets the texture magnification function to either <constant>GL_NEAREST</constant>
                        or <constant>GL_LINEAR</constant> (see below). <constant>GL_NEAREST</constant> is generally faster
                        than <constant>GL_LINEAR</constant>,
                        but it can produce textured images with sharper edges
                        because the transition between texture elements is not as smooth.
                        The initial value of <constant>GL_TEXTURE_MAG_FILTER</constant> is <constant>GL_LINEAR</constant>.
                        <variablelist>
                            <varlistentry>
                                <term><constant>GL_NEAREST</constant></term>
                                <listitem>
                                    <para>
                                        Returns the value of the texture element that is nearest
                                        (in Manhattan distance)
                                        to the center of the pixel being textured.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_LINEAR</constant></term>
                                <listitem>
                                    <para>
                                        Returns the weighted average of the four texture elements
                                        that are closest to the center of the pixel being textured.
                                    </para>
                                </listitem>
                            </varlistentry>
                        </variablelist>
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_MIN_LOD</constant></term>
                <listitem>
                    <para>
                        Sets the minimum level-of-detail parameter.  This floating-point value
                        limits the selection of highest resolution mipmap (lowest mipmap
                        level). The initial value is -1000.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_MAX_LOD</constant></term>
                <listitem>
                    <para>
                        Sets the maximum level-of-detail parameter.  This floating-point value
                        limits the selection of the lowest resolution mipmap (highest mipmap
                        level). The initial value is 1000.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_WRAP_S</constant></term>
                <listitem>
                    <para>
                        Sets the wrap parameter for texture coordinate
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or
                        <constant>GL_REPEAT</constant>. <constant>GL_CLAMP_TO_EDGE</constant> causes
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        coordinates to be clamped to the
                        range
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: left [ {1 over 2N}, 1 - {1 over 2N} right ]: -->
                            <mml:mfenced open="[" close="]">
                                <mml:mfenced open="" close="">
                                    <mml:mrow>
                                        <mml:mfrac>
                                            <mml:mn>1</mml:mn>
                                            <mml:mrow>
                                                <mml:mn>2</mml:mn><mml:mi mathvariant="italic">N</mml:mi>
                                            </mml:mrow>
                                        </mml:mfrac>
                                    </mml:mrow>
                                </mml:mfenced>
                                <mml:mrow>
                                    <mml:mn>1</mml:mn>
                                    <mml:mo>-</mml:mo>
                                    <mml:mfenced open="" close="">
                                        <mml:mrow>
                                            <mml:mfrac>
                                                <mml:mn>1</mml:mn>
                                                <mml:mrow>
                                                    <mml:mn>2</mml:mn><mml:mi mathvariant="italic">N</mml:mi>
                                                </mml:mrow>
                                            </mml:mfrac>
                                        </mml:mrow>
                                    </mml:mfenced>
                                </mml:mrow>
                            </mml:mfenced>
                        </mml:math></inlineequation>,
                        where
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>
                        is the size
                        of the texture in the direction of clamping.  <constant>GL_REPEAT</constant> causes the
                        integer part of the
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        coordinate to be ignored; the GL uses only the
                        fractional part, thereby creating a repeating pattern.
                        <constant>GL_MIRRORED_REPEAT</constant> causes the
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        coordinate to be set to the
                        fractional part of the texture coordinate if the integer part of
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        is
                        even; if the integer part of
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        is odd, then the
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
                        texture coordinate is
                        set to
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: 1 - frac(s): -->
                            <mml:mrow>
                                <mml:mn>1</mml:mn>
                                <mml:mo>-</mml:mo>
                                <mml:mrow>
                                    <mml:mi mathvariant="italic">frac</mml:mi>
                                    <mml:mo>&af;</mml:mo>
                                    <mml:mfenced open="(" close=")">
                                        <mml:mi mathvariant="italic">s</mml:mi>
                                    </mml:mfenced>
                                </mml:mrow>
                            </mml:mrow>
                        </mml:math></inlineequation>,
                        where
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: frac(s): -->
                            <mml:mrow>
                                <mml:mi mathvariant="italic">frac</mml:mi>
                                <mml:mo>&af;</mml:mo>
                                <mml:mfenced open="(" close=")">
                                    <mml:mi mathvariant="italic">s</mml:mi>
                                </mml:mfenced>
                            </mml:mrow>
                        </mml:math></inlineequation>
                        represents the fractional part of
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>.
                        Initially, <constant>GL_TEXTURE_WRAP_S</constant> is set to <constant>GL_REPEAT</constant>.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_WRAP_T</constant></term>
                <listitem>
                    <para>
                        Sets the wrap parameter for texture coordinate
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>
                        to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or
                        <constant>GL_REPEAT</constant>.  See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
                        Initially, <constant>GL_TEXTURE_WRAP_T</constant> is set to <constant>GL_REPEAT</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_TEXTURE_WRAP_R</constant></term>
                <listitem>
                    <para>
                        Sets the wrap parameter for texture coordinate
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
                        to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or
                        <constant>GL_REPEAT</constant>.  See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
                        Initially, <constant>GL_TEXTURE_WRAP_R</constant> is set to <constant>GL_REPEAT</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_TEXTURE_COMPARE_MODE</constant></term>
                <listitem>
                    <para>
                        Specifies the texture comparison mode for currently bound textures.
                        That is, a texture whose base internal format is <constant>GL_DEPTH_COMPONENT</constant> or
                                                <constant>GL_DEPTH_STENCIL</constant>; see
                        <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>)
                        Permissible values are:
                        <variablelist>
                            <varlistentry>
                                <term><constant>GL_COMPARE_REF_TO_TEXTURE</constant></term>
                                <listitem>
                                    <para>
                                        Specifies that the interpolated and clamped
                                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
                                        texture coordinate should
                                        be compared to the value in the currently bound texture.  See the
                                        discussion of <constant>GL_TEXTURE_COMPARE_FUNC</constant> for details of how the comparison
                                        is evaluated.  The result of the comparison is assigned to the red channel.
                                    </para>
                                </listitem>
                            </varlistentry>
                            <varlistentry>
                                <term><constant>GL_NONE</constant></term>
                                <listitem>
                                    <para>
                                        Specifies that the red channel should be assigned the
                                        appropriate value from the currently bound texture.
                                    </para>
                                </listitem>
                            </varlistentry>
                        </variablelist>
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_TEXTURE_COMPARE_FUNC</constant></term>
                <listitem>
                    <para>
                        Specifies the comparison operator used when <constant>GL_TEXTURE_COMPARE_MODE</constant> is
                        set to <constant>GL_COMPARE_REF_TO_TEXTURE</constant>.  Permissible values are:
                        <informaltable>
                            <tgroup cols="2" align="left">
                                <colspec/>
                                <colspec/>
                                <thead>
                                    <row>
                                        <entry>
                                            <emphasis role="bold"> Texture Comparison Function </emphasis>
                                        </entry>
                                        <entry>
                                            <emphasis role="bold"> Computed result </emphasis>
                                        </entry>
                                    </row>
                                </thead>
                                <tbody>
                                    <row>
                                        <entry>
                                        <constant>GL_LEQUAL</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&lt;=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&gt;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_GEQUAL</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&gt;=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&lt;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_LESS</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&lt;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&gt;=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_GREATER</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&gt;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&lt;=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_EQUAL</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&ne;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_NOTEQUAL</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <!-- eqn: result  =  left {   cpile {1.0 above 0.0}        lpile {r <= {D sub t} above r > {D sub t}}: -->
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mfenced open="{" close="">
                                                        <mml:mrow>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>1.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mn>0.0</mml:mn>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                            <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
                                                            <mml:mtable>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>&ne;</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                                <mml:mtr><mml:mtd>
                                                                    <mml:mrow>
                                                                        <mml:mi mathvariant="italic">r</mml:mi>
                                                                        <mml:mo>=</mml:mo>
                                                                        <mml:mfenced open="" close="">
                                                                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                                                                            <mml:mi mathvariant="italic">t</mml:mi>
                                                                            </mml:msub>
                                                                        </mml:mfenced>
                                                                    </mml:mrow>
                                                                </mml:mtd></mml:mtr>
                                                            </mml:mtable>
                                                        </mml:mrow>
                                                    </mml:mfenced>
                                                </mml:mrow>
                                            </mml:math></inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_ALWAYS</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation>
                                                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mi>1.0</mml:mi>
                                                </mml:mrow>
                                                </mml:math>
                                            </inlineequation>
                                        </entry>
                                    </row>
                                    <row>
                                        <entry>
                                        <constant>GL_NEVER</constant>
                                        </entry>
                                        <entry>
                                            <inlineequation>
                                                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                                <mml:mrow>
                                                    <mml:mi mathvariant="italic">result</mml:mi>
                                                    <mml:mo>=</mml:mo>
                                                    <mml:mi>0.0</mml:mi>
                                                </mml:mrow>
                                                </mml:math>
                                            </inlineequation>
                                        </entry>
                                    </row>
                                </tbody>
                            </tgroup>
                        </informaltable>
                        where <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
                        is the current interpolated texture coordinate, and
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: D sub t: -->
                            <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
                            <mml:mi mathvariant="italic">t</mml:mi>
                            </mml:msub>
                        </mml:math></inlineequation>
                        is the texture value sampled from the currently bound texture.
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">result</mml:mi></mml:math></inlineequation>
                        is assigned to
                        <inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                            <!-- eqn: R sub t: -->
                            <mml:msub><mml:mi mathvariant="italic">R</mml:mi>
                            <mml:mi mathvariant="italic">t</mml:mi>
                            </mml:msub>
                        </mml:math></inlineequation>.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <para>
            If a sampler object is bound to a texture unit and that unit is used to sample from a texture, the parameters in the sampler
            are used to sample from the texture, rather than the equivalent parameters in the texture object bound to that unit. This
            introduces the possibility of sampling from the same texture object with different sets of sampler state, which may lead to
            a condition where a texture is <emphasis>incomplete</emphasis> with respect to one sampler object and not with respect to
            another. Thus, completeness can be considered a function of a sampler object and a texture object bound to a single
            texture unit, rather than a property of the texture object itself.
        </para>
        <para>
            The results of a texture lookup are undefined if:
            <itemizedlist>
            <listitem>
                <para>
                    The sampler used in a texture lookup function is not one of the shadow sampler types, the texture object's base
                    internal format is <constant>GL_DEPTH_COMPONENT</constant> or <constant>GL_DEPTH_STENCIL</constant>, and the
                    <constant>GL_TEXTURE_COMPARE_MODE</constant> is not <constant>GL_NONE</constant>.
                </para>
            </listitem>
            <listitem>
                <para>
                    The sampler used in a texture lookup function is one of the shadow sampler types, the texture object's base internal format
                    is <constant>GL_DEPTH_COMPONENT</constant> or <constant>GL_DEPTH_STENCIL</constant>, and the
                    <constant>GL_TEXTURE_COMPARE_MODE</constant> is <constant>GL_NONE</constant>.
                </para>
            </listitem>
            <listitem>
                <para>
                    The sampler used in a texture lookup function is one of the shadow sampler types, and the texture object's base
                    internal format is not <constant>GL_DEPTH_COMPONENT</constant> or <constant>GL_DEPTH_STENCIL</constant>.
                </para>
            </listitem>
            </itemizedlist>
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>sampler</parameter> is not the name of a sampler object previously
            returned from a call to <citerefentry><refentrytitle>glGenSamplers</refentrytitle></citerefentry>.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>params</parameter> should have a defined
            constant value (based on the value of <parameter>pname</parameter>) and does not.
        </para>
    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetSamplerParameter</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="versions">
        <title>API Version Support</title>
        <informaltable>
            <tgroup cols="3" align="left">
                <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
                <tbody>
                    <row>
                        <entry><function>glSamplerParameterf</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='es30']/*)"/>
                    </row>
                    <row>
                        <entry><function>glSamplerParameteri</function></entry>
                        <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='es30']/*)"/>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glGenSamplers</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBindSampler</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDeleteSamplers</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glIsSampler</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glBindTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexParameter</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>
