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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glTexStorage2D">
    <info>
        <copyright>
            <year>2011-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glTexStorage2D</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glTexStorage2D</refname>
        <refpurpose>simultaneously specify storage for all levels of a two-dimensional or one-dimensional array texture</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glTexStorage2D</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLsizei <parameter>levels</parameter></paramdef>
                <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
                <paramdef>GLsizei <parameter>width</parameter></paramdef>
                <paramdef>GLsizei <parameter>height</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Specify the target of the operation. <parameter>target</parameter> must be
                    one of <constant>GL_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_2D</constant>,
                    <constant>GL_TEXTURE_1D_ARRAY</constant>, <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>,
                    <constant>GL_TEXTURE_RECTANGLE</constant>, <constant>GL_PROXY_TEXTURE_RECTANGLE</constant>,
                    or <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>levels</parameter></term>
            <listitem>
                <para>
                    Specify the number of texture levels.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>internalformat</parameter></term>
            <listitem>
                <para>
                    Specifies the sized internal format to be used to store texture image data.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>width</parameter></term>
            <listitem>
                <para>
                    Specifies the width of the texture, in texels.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>height</parameter></term>
            <listitem>
                <para>
                    Specifies the height of the texture, in texels.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            <function>glTexStorage2D</function> specifies the storage requirements for all levels
            of a two-dimensional texture or one-dimensional texture array simultaneously. Once a texture is specified with this
            command, the format and dimensions of all levels become immutable unless it is a proxy
            texture. The contents of the image may still be modified, however, its storage requirements
            may not change. Such a texture is referred to as an <emphasis>immutable-format</emphasis>
            texture.
        </para>
        <para>
            The behavior of <function>glTexStorage2D</function> depends on the <parameter>target</parameter> parameter.
            When <parameter>target</parameter> is <constant>GL_TEXTURE_2D</constant>, <constant>GL_PROXY_TEXTURE_2D</constant>,
            <constant>GL_TEXTURE_RECTANGLE</constant>, <constant>GL_PROXY_TEXTURE_RECTANGLE</constant> or <constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>,
            calling <function>glTexStorage2D</function> is equivalent, assuming no errors are generated,
            to executing the following pseudo-code:
        </para>
<programlisting>    for (i = 0; i &lt; levels; i++) {
        glTexImage2D(target, i, internalformat, width, height, 0, format, type, NULL);
        width = max(1, (width / 2));
        height = max(1, (height / 2));
    }</programlisting>
        <para>
            When <parameter>target</parameter> is <constant>GL_TEXTURE_CUBE_MAP</constant>, <function>glTexStorage2D</function>
            is equivalent to:
        </para>
<programlisting>    for (i = 0; i &lt; levels; i++) {
        for (face in (+X, -X, +Y, -Y, +Z, -Z)) {
            glTexImage2D(face, i, internalformat, width, height, 0, format, type, NULL);
        }
        width = max(1, (width / 2));
        height = max(1, (height / 2));
    }</programlisting>
        <para>
            When <parameter>target</parameter> is <constant>GL_TEXTURE_1D</constant> or <constant>GL_TEXTURE_1D_ARRAY</constant>,
            <function>glTexStorage2D</function> is equivalent to:
        </para>
<programlisting>    for (i = 0; i &lt; levels; i++) {
        glTexImage2D(target, i, internalformat, width, height, 0, format, type, NULL);
        width = max(1, (width / 2));
    }</programlisting>
        <para>
            Since no texture data is actually provided, the values used in the pseudo-code
            for <parameter>format</parameter> and <parameter>type</parameter> are
            irrelevant and may be considered to be any values that are legal for the
            chosen <parameter>internalformat</parameter> enumerant. <parameter>internalformat</parameter>
            must be one of the sized internal formats given in Table 1 below, one of the sized depth-component
            formats <constant>GL_DEPTH_COMPONENT32F</constant>, <constant>GL_DEPTH_COMPONENT24</constant>, or
            <constant>GL_DEPTH_COMPONENT16</constant>, one of the combined depth-stencil formats,
            <constant>GL_DEPTH32F_STENCIL8</constant>, or <constant>GL_DEPTH24_STENCIL8</constant>, or the
            stencil-only format, <constant>GL_STENCIL_INDEX8</constant>. Upon success,
            the value of <constant>GL_TEXTURE_IMMUTABLE_FORMAT</constant> becomes
            <constant>GL_TRUE</constant>. The value of <constant>GL_TEXTURE_IMMUTABLE_FORMAT</constant>
            may be discovered by calling <citerefentry><refentrytitle>glGetTexParameter</refentrytitle></citerefentry>
            with <parameter>pname</parameter> set to <constant>GL_TEXTURE_IMMUTABLE_FORMAT</constant>.
            No further changes to the dimensions or format of the texture object may be
            made. Using any command that might alter the dimensions or format of the
            texture object (such as <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry> or
            another call to <function>glTexStorage2D</function>) will result in the
            generation of a <constant>GL_INVALID_OPERATION</constant> error, even if it
            would not, in fact, alter the dimensions or format of the object.
        </para>
        <para>
            <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="internalformattable.xml"/>
        </para>
    </refsect1>
    <refsect1 xml:id="notes"><title>Notes</title>
        <para>
            <constant>GL_STENCIL_INDEX8</constant> is accepted for <parameter>internalformat</parameter>
            only if the GL version is 4.4 or higher.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not a
            valid sized internal format.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
            one of the accepted target enumerants.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> or <parameter>levels</parameter>
            are less than 1.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>target</parameter> is <constant>GL_TEXTURE_1D_ARRAY</constant>
            or <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant> and <parameter>levels</parameter> is greater than
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                  <mml:mrow>
                    <mml:mfenced open="&lfloor;" close="&rfloor;">
                      <mml:mrow>
                        <mml:msub>
                          <mml:mi>log</mml:mi>
                          <mml:mn>2</mml:mn>
                        </mml:msub>
                        <mml:mfenced open="(" close=")">
                          <mml:mi>width</mml:mi>
                        </mml:mfenced>
                      </mml:mrow>
                    </mml:mfenced>
                    <mml:mo>+</mml:mo>
                    <mml:mn>1</mml:mn>
                  </mml:mrow>
                </mml:math>
            </inlineequation>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>target</parameter> is not <constant>GL_TEXTURE_1D_ARRAY</constant>
            or <constant>GL_PROXY_TEXTURE_1D_ARRAY</constant> and <parameter>levels</parameter> is greater than
            <inlineequation>
                <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                  <mml:mrow>
                    <mml:mfenced open="&lfloor;" close="&rfloor;">
                      <mml:mrow>
                        <mml:msub>
                          <mml:mi>log</mml:mi>
                          <mml:mn>2</mml:mn>
                        </mml:msub>
                        <mml:mfenced open="(" close=")">
                          <mml:mrow>
                            <mml:mi>max</mml:mi>
                            <mml:mfenced open="(" close=")">
                              <mml:mrow>
                                <mml:mi>width</mml:mi>
                                <mml:mo>,</mml:mo>
                                <mml:mtext fontfamily="Times New Roman">&nbsp;</mml:mtext>
                                <mml:mi>height</mml:mi>
                              </mml:mrow>
                            </mml:mfenced>
                          </mml:mrow>
                        </mml:mfenced>
                      </mml:mrow>
                    </mml:mfenced>
                    <mml:mo>+</mml:mo>
                    <mml:mn>1</mml:mn>
                  </mml:mrow>
                </mml:math>
            </inlineequation>.
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexStorage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexStorage3D</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 2011-2013 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>
