<div class="refentry" title="glCompressedTexSubImage2D"><a id="glCompressedTexSubImage2D"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glCompressedTexSubImage2D — specify a two-dimensional compressed texture subimage</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glCompressedTexSubImage2D</b>(</code></td><td>GLenum <var class="pdparam">target</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>GLsizei <var class="pdparam">width</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">height</var>, </td></tr><tr><td> </td><td>GLenum <var class="pdparam">format</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">imageSize</var>, </td></tr><tr><td> </td><td>const GLvoid * <var class="pdparam">data</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><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>.</p></dd><dt><span class="term">

<em class="parameter"><code>level</code></em>

</span></dt><dd><p>Specifies the level-of-detail number.</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 pixel data.

Currently, there is no supported format.</p></dd><dt><span class="term">

<em class="parameter"><code>imageSize</code></em>

</span></dt><dd><p>Specifies the size of the compressed pixel data in bytes.</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" title="Description"><a id="description"></a><h2>Description</h2><p>

<code class="function">glCompressedTexSubImage2D</code>

redefines a contiguous subregion of an existing two-dimensional

compressed texture image.

The texels referenced by <em class="parameter"><code>pixels</code></em>

replace the portion of the existing texture array with x indices

<em class="parameter"><code>xoffset</code></em> and

<math overflow="scroll">

<mi>xoffset</mi><mo>+</mo><mi>width</mi><mo>-</mo><mn>1</mn>

</math>,

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

<math overflow="scroll">

<mi>yoffset</mi><mo>+</mo><mi>height</mi><mo>-</mo><mn>1</mn>

</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 zero width or

height, but such a specification has no effect.</p><p><em class="parameter"><code>format</code></em> must be the same compressed-texture format

previously specified by

<a class="citerefentry" href="glCompressedTexImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>.</p><p>The required paletted formats do not allow subimage updates,

but other formats defined by extensions may.</p></div><div class="refsect1" title="Notes"><a id="notes"></a><h2>Notes</h2><p><a class="citerefentry" href="glPixelStorei"><span class="citerefentry"><span class="refentrytitle">glPixelStorei</span></span></a>

has no effect on compressed texture images.</p><p>

<code class="function">glCompressedTexSubImage2D</code>

specifies the two-dimensional sub texture for the currently bound texture,

specified with

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

and the current texture

unit, specified with

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

</p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_ENUM</code> is generated if

<em class="parameter"><code>target</code></em> is not <code class="constant">GL_TEXTURE_2D</code>.

</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if

<em class="parameter"><code>level</code></em> is less than 0.</p><p><code class="constant">GL_INVALID_VALUE</code> may be generated if

<em class="parameter"><code>level</code></em> is greater than

<math overflow="scroll">

<msub><mo>log</mo><mn>2</mn></msub><mi>max</mi>

</math>, where

<em class="replaceable"><code>max</code></em> is the returned value of

<code class="constant">GL_MAX_TEXTURE_SIZE</code>.</p><p>

<code class="constant">GL_INVALID_VALUE</code> is generated if

<math overflow="scroll">

<mrow>

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

<mo>&lt;</mo>

0

</mrow>

</math>,

<math overflow="scroll">

<mrow>

<mfenced open="(" close=")">

<mrow>

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

<mo>+</mo>

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

</mrow>

</mfenced>

<mo>&gt;</mo>

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

</mrow>

</math>,

<math overflow="scroll">

<mrow>

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

<mo>&lt;</mo>

0

</mrow>

</math>,

or

<math overflow="scroll">

<mrow>

<mfenced open="(" close=")">

<mrow>

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

<mo>+</mo>

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

</mrow>

</mfenced>

<mo>&gt;</mo>

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

</mrow>

</math>,

where

<math overflow="scroll"><mi mathvariant="italic">w</mi></math>

is the width and

<math overflow="scroll"><mi mathvariant="italic">h</mi></math>

is the height

of the texture image being modified.

</p><p><code class="constant">GL_INVALID_VALUE</code> is generated if

<em class="parameter"><code>width</code></em> or

<em class="parameter"><code>height</code></em> is less than 0.</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if the texture array has not

been defined by a previous

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

operation whose <em class="parameter"><code>internalformat</code></em> matches the <em class="parameter"><code>format</code></em>

of <code class="function">glCompressedTexSubImage2D</code>.

</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>

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" title="Associated Gets"><a id="associatedgets"></a><h2>Associated Gets</h2><p>

<a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with arguments

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

<code class="constant">GL_COMPRESSED_TEXTURE_FORMATS</code>

</p><p>

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

with argument <code class="constant">GL_MAX_TEXTURE_SIZE</code></p></div><div class="refsect1" title="See Also"><a id="seealso"></a><h2>See Also</h2><p>

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

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

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

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

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

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

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

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

</p></div><div class="refsect1" title="Copyright"><a id="copyright"></a><h2>Copyright</h2><p>

Copyright © 2003-2004

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

Free Software B License. For details, see

<a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.

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