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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glGetTextureSubImage">
<info>
<copyright>
<year>2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>glGetTextureSubImage</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glGetTextureSubImage</refname>
<refpurpose>retrieve a sub-region of a texture image from a texture
object</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetTextureSubImage</function></funcdef>
<paramdef>GLuint <parameter>texture</parameter></paramdef>
<paramdef>GLint <parameter>level</parameter></paramdef>
<paramdef>GLint <parameter>xoffset</parameter></paramdef>
<paramdef>GLint <parameter>yoffset</parameter></paramdef>
<paramdef>GLint <parameter>zoffset</parameter></paramdef>
<paramdef>GLsizei <parameter>width</parameter></paramdef>
<paramdef>GLsizei <parameter>height</parameter></paramdef>
<paramdef>GLsizei <parameter>depth</parameter></paramdef>
<paramdef>GLenum <parameter>format</parameter></paramdef>
<paramdef>GLenum <parameter>type</parameter></paramdef>
<paramdef>GLsizei <parameter>bufSize</parameter></paramdef>
<paramdef>void *<parameter>pixels</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters">
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>texture</parameter></term>
<listitem>
<para>Specifies the name of the source texture object. Must be
<constant>GL_TEXTURE_1D</constant>,
<constant>GL_TEXTURE_1D_ARRAY</constant>,
<constant>GL_TEXTURE_2D</constant>,
<constant>GL_TEXTURE_2D_ARRAY</constant>,
<constant>GL_TEXTURE_3D</constant>,
<constant>GL_TEXTURE_CUBE_MAP</constant>,
<constant>GL_TEXTURE_CUBE_MAP_ARRAY</constant> or
<constant>GL_TEXTURE_RECTANGLE</constant>. In specific, buffer and
multisample textures are not permitted.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>level</parameter></term>
<listitem>
<para>Specifies the level-of-detail number. Level 0 is the base
image level. Level $n$ is the $n$th mipmap reduction image.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>xoffset</parameter></term>
<listitem>
<para>Specifies a texel offset in the x direction within the texture
array.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>yoffset</parameter></term>
<listitem>
<para>Specifies a texel offset in the y direction within the texture
array.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>zoffset</parameter></term>
<listitem>
<para>Specifies a texel offset in the z direction within the texture
array.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>width</parameter></term>
<listitem>
<para>Specifies the width of the texture subimage.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>height</parameter></term>
<listitem>
<para>Specifies the height of the texture subimage.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>depth</parameter></term>
<listitem>
<para>Specifies the depth of the texture subimage.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>format</parameter></term>
<listitem>
<para>Specifies the format of the pixel data. The following symbolic
values are accepted: <constant>GL_RED</constant>,
<constant>GL_RG</constant>, <constant>GL_RGB</constant>,
<constant>GL_BGR</constant>, <constant>GL_RGBA</constant>,
<constant>GL_BGRA</constant>,
<constant>GL_DEPTH_COMPONENT</constant> and
<constant>GL_STENCIL_INDEX</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>type</parameter></term>
<listitem>
<para>Specifies the data type of the pixel data. The following
symbolic values are accepted: <constant>GL_UNSIGNED_BYTE</constant>,
<constant>GL_BYTE</constant>,
<constant>GL_UNSIGNED_SHORT</constant>,
<constant>GL_SHORT</constant>, <constant>GL_UNSIGNED_INT</constant>,
<constant>GL_INT</constant>, <constant>GL_FLOAT</constant>,
<constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
<constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
<constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
<constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
<constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
<constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
<constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
<constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
<constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
<constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
<constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
<constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>bufSize</parameter></term>
<listitem>
<para>Specifies the size of the buffer to receive the retrieved
pixel data.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pixels</parameter></term>
<listitem>
<para>Returns the texture subimage. Should be a pointer to an array
of the type specified by <parameter>type</parameter>.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description">
<title>Description</title>
<para><function>glGetTextureSubImage</function> returns a texture subimage
into pixels.</para>
<para><parameter>texture</parameter> is the name of the source texture
object and must not be a buffer or multisample texture. The effective
<parameter>target</parameter> parameter is the value of
<constant>GL_TEXTURE_TARGET</constant> for texture.
<parameter>Level</parameter>, <parameter>format</parameter>,
<parameter>type</parameter> and <parameter>pixels</parameter> have the
same meaning as for <function>glGetTexImage</function>.
<parameter>bufSize</parameter> is the size of the buffer to receive the
retrieved pixel data.</para>
<para>For cube map textures, the behavior is as though
<function>GetTextureImage</function> were called, but only texels from the
requested cube map faces (selected by <parameter>zoffset</parameter> and
<parameter>depth</parameter>, as described below) were returned.</para>
<para><parameter>xoffset</parameter>, <parameter>yoffset</parameter> and
<parameter>zoffset</parameter> values indicate the position of the
subregion to return. <parameter>width</parameter>,
<parameter>height</parameter> and <parameter>depth</parameter> indicate
the size of the region to return. These parameters have the same meaning
as for <function>glTexSubImage3D</function>, though for one- and
two-dimensional textures there are extra restrictions, described in the
errors section below.</para>
<para>For one-dimensional array textures, <parameter>yoffset</parameter>
is interpreted as the first layer to access and
<parameter>height</parameter> is the number of layers to access.</para>
<para>For two-dimensional array textures, <parameter>zoffset</parameter>
is interpreted as the first layer to access and
<parameter>depth</parameter> is the number of layers to access.</para>
<para>Cube map textures are treated as an array of six slices in the
z-dimension, where the value of <parameter>zoffset</parameter> is
interpreted as specifying the cube map face for the corresponding layer
(as presented in the table below) and <parameter>depth</parameter> is the
number of faces to access:</para>
<para><informaltable>
<tgroup cols="2">
<tbody>
<row>
<entry>Layer number</entry>
<entry>Cube Map Face</entry>
</row>
<row>
<entry>0</entry>
<entry>GL_TEXTURE_CUBE_MAP_POSITIVE_X</entry>
</row>
<row>
<entry>1</entry>
<entry>GL_TEXTURE_CUBE_MAP_NEGATIVE_X</entry>
</row>
<row>
<entry>2</entry>
<entry>GL_TEXTURE_CUBE_MAP_POSITIVE_Y</entry>
</row>
<row>
<entry>3</entry>
<entry>GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</entry>
</row>
<row>
<entry>4</entry>
<entry>GL_TEXTURE_CUBE_MAP_POSITIVE_Z</entry>
</row>
<row>
<entry>5</entry>
<entry>GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</entry>
</row>
</tbody>
</tgroup>
</informaltable></para>
<para>
For cube map array textures, <parameter>zoffset</parameter> is the
first layer-face to access, and <parameter>depth</parameter> is the
number of layer-faces to access. A layer-face described by $k$ is
translated into an array layer and face according to
$$ layer = \left\lfloor { layer \over 6 } \right\rfloor$$
and
$$ face = k \bmod 6. $$
</para>
<para>Component groups from the specified sub-region are packed and placed
into memory as described for <function>glGetTextureImage</function>,
starting with the texel at (<parameter>xoffset</parameter>,
<parameter>yoffset</parameter>, <parameter>zoffset</parameter>).</para>
</refsect1>
<refsect1 xml:id="errors">
<title>Errors</title>
<para><constant>GL_INVALID_VALUE</constant> error is generated if
<parameter>texture</parameter> is not the name of an existing texture
object.</para>
<para><constant>GL_INVALID_OPERATION</constant> error is generated if
<parameter>texture</parameter> is the name of a buffer or multisample
texture.</para>
<para><constant>GL_INVALID_VALUE</constant> is generated if
<parameter>xoffset</parameter>, <parameter>yoffset</parameter> or
<parameter>zoffset</parameter> are negative.</para>
<para><constant>GL_INVALID_VALUE</constant> is generated if
<parameter>xoffset</parameter> + <parameter>width</parameter> is greater
than the texture's width, <parameter>yoffset</parameter> +
<parameter>height</parameter> is greater than the texture's height, or
<parameter>zoffset</parameter> + <parameter>depth</parameter> is greater
than the texture's depth.</para>
<para><constant>GL_INVALID_VALUE</constant> error is generated if the
effective target is <constant>GL_TEXTURE_1D</constant> and either
<parameter>yoffset</parameter> is not zero, or
<parameter>height</parameter> is not one.</para>
<para><constant>GL_INVALID_VALUE</constant> error is generated if the
effective target is <constant>GL_TEXTURE_1D</constant>,
<constant>GL_TEXTURE_1D_ARRAY</constant>,
<constant>GL_TEXTURE_2D</constant> or
<constant>GL_TEXTURE_RECTANGLE</constant> and either
<parameter>zoffset</parameter> is not zero, or
<parameter>depth</parameter> is not one.</para>
<para><constant>GL_INVALID_OPERATION</constant> error is generated if the
buffer size required to store the requested data is greater than
<parameter>bufSize</parameter>.</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>glGetTextureSubImage</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>glGetTexImage</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glGetTextureImage</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glReadPixels</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexImage1D</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexImage2D</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexImage3D</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexSubImage1D</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexSubImage2D</refentrytitle>
</citerefentry>, <citerefentry>
<refentrytitle>glTexSubImage3D</refentrytitle>
</citerefentry></para>
</refsect1>
<refsect1 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 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>
|
