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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>glGetCompressedTextureSubImage - OpenGL 4 Reference Pages</title>
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<header/>
<div class="refentry" id="glGetCompressedTextureSubImage">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>glGetCompressedTextureSubImage — retrieve a sub-region of a compressed texture image from a
compressed texture object</p>
</div>
<div class="refsynopsisdiv">
<h2>C Specification</h2>
<div class="funcsynopsis">
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">void <strong class="fsfunc">glGetCompressedTextureSubImage</strong>(</code>
</td>
<td>GLuint <var class="pdparam">texture</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLint <var class="pdparam">level</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLint <var class="pdparam">xoffset</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLint <var class="pdparam">yoffset</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLint <var class="pdparam">zoffset</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLsizei <var class="pdparam">width</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLsizei <var class="pdparam">height</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLsizei <var class="pdparam">depth</var>, </td>
</tr>
<tr>
<td> </td>
<td>GLsizei <var class="pdparam">bufSize</var>, </td>
</tr>
<tr>
<td> </td>
<td>void *<var class="pdparam">pixels</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
</div>
<div class="refsect1" id="parameters">
<h2>Parameters</h2>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<em class="parameter">
<code>texture</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the name of the source texture object. Must be
<code class="constant">GL_TEXTURE_1D</code>,
<code class="constant">GL_TEXTURE_1D_ARRAY</code>,
<code class="constant">GL_TEXTURE_2D</code>,
<code class="constant">GL_TEXTURE_2D_ARRAY</code>,
<code class="constant">GL_TEXTURE_3D</code>,
<code class="constant">GL_TEXTURE_CUBE_MAP</code>,
<code class="constant">GL_TEXTURE_CUBE_MAP_ARRAY</code> or
<code class="constant">GL_TEXTURE_RECTANGLE</code>. In specific, buffer and
multisample textures are not permitted.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>level</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the level-of-detail number. Level 0 is the base
image level. Level $n$ is the $n$th
mipmap reduction image.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>xoffset</code>
</em>
</span>
</dt>
<dd>
<p>Specifies a texel offset in the x direction within the texture
array.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>yoffset</code>
</em>
</span>
</dt>
<dd>
<p>Specifies a texel offset in the y direction within the texture
array.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>zoffset</code>
</em>
</span>
</dt>
<dd>
<p>Specifies a texel offset in the z direction within the texture
array.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>width</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the width of the texture subimage. Must be a
multiple of the compressed block's width, unless the
<em class="parameter"><code>offset</code></em> is zero and the size equals the texture
image size.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>height</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the height of the texture subimage. Must be a
multiple of the compressed block's height, unless the
<em class="parameter"><code>offset</code></em> is zero and the size equals the texture
image size.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>depth</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the depth of the texture subimage. Must be a
multiple of the compressed block's depth, unless the
<em class="parameter"><code>offset</code></em> is zero and the size equals the texture
image size.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>bufSize</code>
</em>
</span>
</dt>
<dd>
<p>Specifies the size of the buffer to receive the retrieved
pixel data.</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>pixels</code>
</em>
</span>
</dt>
<dd>
<p>Returns the texture subimage. Should be a pointer to an array
of the type specified by type.</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p><code class="function">glGetCompressedTextureSubImage</code> can be used to
obtain a sub-region of a compressed texture image instead of the whole
image, as long as the compressed data are arranged into fixed-size blocks
of texels. <em class="parameter"><code>texture</code></em> is the name of the texture
object, and must not be a buffer or multisample texture. The effective
<em class="parameter"><code>target</code></em> is the value of
<code class="constant">GL_TEXTURE_TARGET</code> for texture.
<em class="parameter"><code>level</code></em> and <em class="parameter"><code>pixels</code></em> have the
same meaning as the corresponding arguments of
<code class="function">glCompressedTexSubImage3D</code>.
<em class="parameter"><code>bufSize</code></em> indicates the size of the buffer to receive
the retrieved pixel data.</p>
<p>For cube map textures, the behavior is as though
<code class="function">glGetCompressedTexImage</code> were called once for each
requested face (selected by <em class="parameter"><code>zoffset</code></em> and
<em class="parameter"><code>depth</code></em>, as described below) with target
corresponding to the requested texture cube map face as indicated by the
table presented below. <em class="parameter"><code>pixels</code></em> is offset
appropriately for each successive image.</p>
<div class="informaltable">
<table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
<colgroup>
<col/>
<col/>
</colgroup>
<tbody>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">Layer number</td>
<td style="border-bottom: 2px solid ; ">Cube Map Face</td>
</tr>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">0</td>
<td style="border-bottom: 2px solid ; ">
<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>
</td>
</tr>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">1</td>
<td style="border-bottom: 2px solid ; ">
<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_X</code>
</td>
</tr>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">2</td>
<td style="border-bottom: 2px solid ; ">
<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Y</code>
</td>
</tr>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">3</td>
<td style="border-bottom: 2px solid ; ">
<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</code>
</td>
</tr>
<tr>
<td style="border-right: 2px solid ; border-bottom: 2px solid ; ">4</td>
<td style="border-bottom: 2px solid ; ">
<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Z</code>
</td>
</tr>
<tr>
<td style="border-right: 2px solid ; ">5</td>
<td>
<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>
</td>
</tr>
</tbody>
</table>
</div>
<p><em class="parameter"><code>xoffset</code></em>, <em class="parameter"><code>yoffset</code></em> and
<em class="parameter"><code>zoffset</code></em> indicate the position of the subregion to
return. <em class="parameter"><code>width</code></em>, <em class="parameter"><code>height</code></em> and
<em class="parameter"><code>depth</code></em> indicate the size of the region to return.
These arguments have the same meaning as for
<code class="function">glCompressedTexSubImage3D</code>, though there are extra
restrictions, described in the errors section below.</p>
<p>The mapping between the <em class="parameter"><code>xoffset</code></em>,
<em class="parameter"><code>yoffset</code></em>, <em class="parameter"><code>zoffset</code></em>,
<em class="parameter"><code>width</code></em>, <em class="parameter"><code>height</code></em> and
<em class="parameter"><code>depth</code></em> parameters and the faces, layers, and
layer-faces for cube map, array, and cube map array textures is the same
as for glGetTextureSubImage.</p>
<p>The <em class="parameter"><code>xoffset</code></em>, <em class="parameter"><code>yoffset</code></em>,
<em class="parameter"><code>zoffset</code></em> offsets and <em class="parameter"><code>width</code></em>,
<em class="parameter"><code>height</code></em> and <em class="parameter"><code>depth</code></em> sizes must
be multiples of the values of
<code class="constant">GL_PACK_COMPRESSED_BLOCK_WIDTH</code>,
<code class="constant">GL_PACK_COMPRESSED_BLOCK_HEIGHT</code>, and
<code class="constant">GL_PACK_COMPRESSED_BLOCK_DEPTH</code> respectively, unless
<em class="parameter"><code>offset</code></em> is zero and the corresponding
<em class="parameter"><code>size</code></em> is the same as the texture size in that
dimension.</p>
<p>Pixel storage modes are treated as for
<code class="function">glGetCompressedTexSubImage</code>. The texel at
(<em class="parameter"><code>xoffset</code></em>, <em class="parameter"><code>yoffset</code></em>,
<em class="parameter"><code>zoffset</code></em>) will be stored at the location indicated
by <em class="parameter"><code>pixels</code></em> and the current pixel packing parameters.</p>
</div>
<div class="refsect1" id="errors">
<h2>Errors</h2>
<p><code class="constant">GL_INVALID_OPERATION</code> error is generated if
<em class="parameter"><code>texture</code></em> is the name of a buffer or multisample
texture.</p>
<p><code class="constant">GL_INVALID_OPERATION</code> error is generated if the
buffer size required to store the requested data is greater than
<em class="parameter"><code>bufSize</code></em>.</p>
<p><code class="constant">GL_INVALID_OPERATION</code> error is generated if the
texture compression format is not based on fixed-size blocks.</p>
<p><code class="constant">GL_INVALID_VALUE</code> error is generated if
<em class="parameter"><code>texture</code></em> is not the name of an existing texture
object.</p>
<p><code class="constant">GL_INVALID_VALUE</code> is generated if
<em class="parameter"><code>xoffset</code></em>, <em class="parameter"><code>yoffset</code></em> or
<em class="parameter"><code>zoffset</code></em> are negative.</p>
<p><code class="constant">GL_INVALID_VALUE</code> is generated if
<em class="parameter"><code>xoffset</code></em> + <em class="parameter"><code>width</code></em> is greater
than the texture's width, <em class="parameter"><code>yoffset</code></em> +
<em class="parameter"><code>height</code></em> is greater than the texture's height, or
<em class="parameter"><code>zoffset</code></em> + <em class="parameter"><code>depth</code></em> is greater
than the texture's depth.</p>
<p><code class="constant">GL_INVALID_VALUE</code> error is generated if the
effective target is <code class="constant">GL_TEXTURE_1D</code> and either
<em class="parameter"><code>yoffset</code></em> is not zero, or
<em class="parameter"><code>height</code></em> is not one.</p>
<p><code class="constant">GL_INVALID_VALUE</code> error is generated if the
effective target is <code class="constant">GL_TEXTURE_1D</code>,
<code class="constant">GL_TEXTURE_1D_ARRAY</code>,
<code class="constant">GL_TEXTURE_2D</code> or
<code class="constant">GL_TEXTURE_RECTANGLE</code> and either
<em class="parameter"><code>zoffset</code></em> is not zero, or
<em class="parameter"><code>depth</code></em> is not one.</p>
<p><code class="constant">GL_INVALID_VALUE</code> error is generated if
<em class="parameter"><code>xoffset</code></em>, <em class="parameter"><code>yoffset</code></em> or
<em class="parameter"><code>zoffset</code></em> is not a multiple of the compressed block
width, height or depth respectively.</p>
<p><code class="constant">GL_INVALID_VALUE</code> error is generated if
<em class="parameter"><code>width</code></em>, <em class="parameter"><code>height</code></em> or
<em class="parameter"><code>depth</code></em> is not a multiple of the compressed block
width, height or depth respectively, unless the
<em class="parameter"><code>offset</code></em> is zero and the <em class="parameter"><code>size</code></em>
equals the texture image size.</p>
</div>
<div class="refsect1" id="versions">
<h2>Version Support</h2>
<div class="informaltable">
<table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
<colgroup>
<col style="text-align: left; "/>
<col style="text-align: center; " class="firstvers"/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; " class="lastvers"/>
</colgroup>
<thead>
<tr>
<th style="text-align: left; border-right: 2px solid ; ">
</th>
<th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
<span class="bold"><strong>OpenGL Version</strong></span>
</th>
</tr>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>Function / Feature Name</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>2.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.4</strong></span>
</th>
<th style="text-align: center; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.5</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; ">
<code class="function">glGetCompressedTextureSubImage</code>
</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; ">-</td>
<td style="text-align: center; ">✔</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="refsect1" id="seealso">
<h2>See Also</h2>
<p><a class="citerefentry" href="glCompressedTexImage1D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage1D</span></span></a>, <a class="citerefentry" href="glCompressedTexImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>, <a class="citerefentry" href="glCompressedTexImage3D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage3D</span></span></a>, <a class="citerefentry" href="glCompressedTexSubImage1D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>, <a class="citerefentry" href="glCompressedTexSubImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</span></span></a>, <a class="citerefentry" href="glCompressedTexSubImage3D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage3D</span></span></a>, <a class="citerefentry" href="glGetCompressedTexImage.xhtml"><span class="citerefentry"><span class="refentrytitle">glGetCompressedTexImage</span></span></a>, <a class="citerefentry" href="glGetCompressedTextureImage.xhtml"><span class="citerefentry"><span class="refentrytitle">glGetCompressedTextureImage</span></span></a>, <a class="citerefentry" href="glReadPixels.xhtml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a></p>
</div>
<div class="refsect1" id="Copyright">
<h2>Copyright</h2>
<p>
Copyright <span class="trademark"/>© 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.
<a class="link" href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
</p>
</div>
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<footer/>
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