<div class="refentry" lang="en" xml:lang="en"><a id="glCompressedTexSubImage2D"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glCompressedTexSubImage2D — specify a two-dimensional texture subimage in a compressed format</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table><tr><td><code class="funcdef">void <b class="fsfunc">glCompressedTexSubImage2D</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">level</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">xoffset</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">yoffset</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">width</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">height</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">format</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">imageSize</var>, </td></tr><tr><td> </td><td>const GLvoid *  </td><td><var class="pdparam">data</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>target</code></em></span></dt><dd><p>

Specifies the target texture.

Must be <code class="constant">GL_TEXTURE_2D</code>,

<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>,

<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_X</code>,

<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Y</code>,

<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</code>,

<code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Z</code>, or

<code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>.

</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 <span class="emphasis"><em>n</em></span> is the <span class="emphasis"><em>n</em></span>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>width</code></em></span></dt><dd><p>

Specifies the width of the texture subimage.

</p></dd><dt><span class="term"><em class="parameter"><code>height</code></em></span></dt><dd><p>

Specifies the height of the texture subimage.

</p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>

Specifies the format of the compressed image data stored at address <em class="parameter"><code>data</code></em>.

</p></dd><dt><span class="term"><em class="parameter"><code>imageSize</code></em></span></dt><dd><p>

Specifies the number of unsigned bytes of image data starting at the

address specified by <em class="parameter"><code>data</code></em>.

</p></dd><dt><span class="term"><em class="parameter"><code>data</code></em></span></dt><dd><p>

Specifies a pointer to the compressed image data in memory.

</p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>

Texturing allows elements of an image array to be read by shaders.

</p><p>

<code class="function">glCompressedTexSubImage2D</code> redefines a contiguous subregion of an existing two-dimensional

texture image. The texels referenced by <em class="parameter"><code>data</code></em> replace the portion of the

existing texture array with x indices <em class="parameter"><code>xoffset</code></em> and

<math overflow="scroll">

<mrow>

<mi mathvariant="italic">xoffset</mi>

<mo>+</mo>

<mi mathvariant="italic">width</mi>

<mo>-</mo>

<mn>1</mn>

</mrow>

</math>,

and the y indices <em class="parameter"><code>yoffset</code></em> and

<math overflow="scroll">

<mrow>

<mi mathvariant="italic">yoffset</mi>

<mo>+</mo>

<mi mathvariant="italic">height</mi>

<mo>-</mo>

<mn>1</mn>

</mrow>

</math>,

inclusive.

This region may not include any texels

outside the range of the texture array as it was originally specified. It

is not an error to specify a subtexture with width of 0, but such a

specification has no effect.

</p><p>

<em class="parameter"><code>internalformat</code></em> must be a known compressed image format (such as <code class="constant">GL_RGTC</code>)

or an extension-specified compressed-texture format.

The <em class="parameter"><code>format</code></em> of the compressed texture

image is selected by the GL implementation that compressed it (see

<a href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>) and should be queried at the time the texture was

compressed with <a href="glGetTexLevelParameter"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a>.

</p><p>

If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_UNPACK_BUFFER</code> target

(see <a href="glBindBuffer"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a texture image is

specified, <em class="parameter"><code>data</code></em> is treated as a byte offset into the buffer object's data store.

</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>

<code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>internalformat</code></em> is of the generic compressed internal formats:

<code class="constant">GL_COMPRESSED_RED</code>,

<code class="constant">GL_COMPRESSED_RG</code>,

<code class="constant">GL_COMPRESSED_RGB</code>,

<code class="constant">GL_COMPRESSED_RGBA</code>.

<code class="constant">GL_COMPRESSED_SRGB</code>, or

<code class="constant">GL_COMPRESSED_SRGB_ALPHA</code>.

</p><p>

<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>imageSize</code></em> is not consistent with

the format, dimensions, and contents of the specified compressed image

data.

</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if parameter combinations are not

supported by the specific compressed internal format as specified in the

specific texture compression extension.

</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the

<code class="constant">GL_PIXEL_UNPACK_BUFFER</code> target and the buffer object's data store is currently mapped.

</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the

<code class="constant">GL_PIXEL_UNPACK_BUFFER</code> target and the data would be unpacked from the buffer

object such that the memory reads required would exceed the data store size.

</p><p>

Undefined results, including abnormal program termination, are generated if

<em class="parameter"><code>data</code></em> is not encoded in a manner consistent with the extension

specification defining the internal compression format.

</p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>

<a href="glGetCompressedTexImage"><span class="citerefentry"><span class="refentrytitle">glGetCompressedTexImage</span></span></a>

</p><p>

<a href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_TEXTURE_COMPRESSED</code>

</p><p>

<a href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PIXEL_UNPACK_BUFFER_BINDING</code>

</p><p>

<a href="glGetTexLevelParameter"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with arguments <code class="constant">GL_TEXTURE_INTERNAL_FORMAT</code>

and <code class="constant">GL_TEXTURE_COMPRESSED_IMAGE_SIZE</code>

</p></div>

{$pipelinestall}{$examples}

<div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>

<a href="glActiveTexture"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,

<a href="glCompressedTexImage1D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage1D</span></span></a>,

<a href="glCompressedTexImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>,

<a href="glCompressedTexImage3D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage3D</span></span></a>,

<a href="glCompressedTexSubImage1D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>,

<a href="glCompressedTexSubImage3D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage3D</span></span></a>,

<a href="glCopyTexImage1D"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage1D</span></span></a>,

<a href="glCopyTexImage2D"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>,

<a href="glCopyTexSubImage1D"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage1D</span></span></a>,

<a href="glCopyTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,

<a href="glCopyTexSubImage3D"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage3D</span></span></a>,

<a href="glPixelStore"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>,

<a href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,

<a href="glTexImage3D"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,

<a href="glTexSubImage1D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,

<a href="glTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,

<a href="glTexSubImage3D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>,

<a href="glTexParameter"><span class="citerefentry"><span class="refentrytitle">glTexParameter</span></span></a>

</p></div><div class="refsect1" lang="en" xml:lang="en"><div id="Copyright"><h2>Copyright</h2><p>

Copyright © 1991-2006

Silicon Graphics, Inc. This document is licensed under the SGI

Free Software B License. For details, see

<a href="https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/" target="_top">https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/</a>.

</p></div></div></div>