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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glTexStorage2D">
<info>
<copyright>
<year>2011-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>glTexStorage2D</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glTexStorage2D</refname>
<refname>glTextureStorage2D</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>
<funcprototype>
<funcdef>void <function>glTextureStorage2D</function></funcdef>
<paramdef>GLuint <parameter>texture</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>
Specifies the target to which the texture object is
bound for <function>glTexStorage2D</function>. Must be
one of <constant>GL_TEXTURE_2D</constant>,
<constant>GL_TEXTURE_1D_ARRAY</constant>,
<constant>GL_TEXTURE_RECTANGLE</constant>,
<constant>GL_PROXY_TEXTURE_2D</constant>,
<constant>GL_PROXY_TEXTURE_1D_ARRAY</constant>,
<constant>GL_PROXY_TEXTURE_RECTANGLE</constant>, or
<constant>GL_PROXY_TEXTURE_CUBE_MAP</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>texture</parameter></term>
<listitem>
<para>
Specifies the texture object name for
<function>glTextureStorage2D</function>. The effective
target of <parameter>texture</parameter> must be one of
the valid non-proxy <parameter>target</parameter> values
above.
</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> and
<function>glTextureStorage2D</function> specify 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 < 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 < 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 < levels; i++) {
glTexImage2D(target, i, internalformat, width, height, 0, format, type, NULL);
width = max(1, (width / 2));
}</programlisting>
<para>
Calling <function>glTextureStorage2D</function> is equivalent to the
above pseudo-code, where <parameter>target</parameter> is the
effective target of <parameter>texture</parameter> and it is as
if <parameter>texture</parameter> were bound to
<parameter>target</parameter> for the purposes of
<function>glTexImage2D</function>.
</para>
<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_OPERATION</constant> is generated by
<function>glTexStorage2D</function> if zero is bound to
<parameter>target</parameter>.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated by
<function>glTextureStorage2D</function> if
<parameter>texture</parameter> is not the name of an existing
texture object.
</para>
<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> or the effective target of
<parameter>texture</parameter> is not one of the accepted
targets described above.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if
<parameter>width</parameter>, <parameter>height</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="⌊" close="⌋">
<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="⌊" close="⌋">
<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"> </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="versions"><title>Version Support</title>
<informaltable>
<tgroup cols="13" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apifunchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry><function>glTexStorage2D</function></entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='42']/*)"/>
</row>
<row>
<entry><function>glTextureStorage2D</function></entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="apiversion.xml" xpointer="xpointer(/*/*[@role='45']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</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"/> 2011-2014 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>
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