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<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glCompressedTexSubImage2D</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><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"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glCompressedTexSubImage2D</strong>(</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"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><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"><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
        <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
            <mml:mi>xoffset</mml:mi><mml:mo>+</mml:mo><mml:mi>width</mml:mi><mml:mo>-</mml:mo><mml:mn>1</mml:mn>
        </mml:math>,
        inclusive, and y indices <em class="parameter"><code>yoffset</code></em> and
        <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
            <mml:mi>yoffset</mml:mi><mml:mo>+</mml:mo><mml:mi>height</mml:mi><mml:mo>-</mml:mo><mml:mn>1</mml:mn>
        </mml: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.xml"><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"><a id="notes"></a><h2>Notes</h2><p><a class="citerefentry" href="glPixelStorei.xml"><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.xml"><span class="citerefentry"><span class="refentrytitle">glBindTexture</span></span></a>,
        and the current texture
        unit, specified with
        <a class="citerefentry" href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>.
        </p></div><div class="refsect1"><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
        <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
            <mml:msub><mml:mo>log</mml:mo><mml:mn>2</mml:mn></mml:msub><mml:mi>max</mml:mi>
        </mml: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 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">xoffset</mml:mi>
                    <mml:mo>&lt;</mml:mo>
                    0
                </mml:mrow>
            </mml:math>,
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mfenced open="(" close=")">
                        <mml:mrow>
                            <mml:mi mathvariant="italic">xoffset</mml:mi>
                            <mml:mo>+</mml:mo>
                            <mml:mi mathvariant="italic">width</mml:mi>
                        </mml:mrow>
                    </mml:mfenced>
                    <mml:mo>&gt;</mml:mo>
                    <mml:mi mathvariant="italic">w</mml:mi>
                </mml:mrow>
            </mml:math>,
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mi mathvariant="italic">yoffset</mml:mi>
                    <mml:mo>&lt;</mml:mo>
                    0
                </mml:mrow>
            </mml:math>,
            or 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                
                <mml:mrow>
                    <mml:mfenced open="(" close=")">
                        <mml:mrow>
                            <mml:mi mathvariant="italic">yoffset</mml:mi>
                            <mml:mo>+</mml:mo>
                            <mml:mi mathvariant="italic">height</mml:mi>
                        </mml:mrow>
                    </mml:mfenced>
                    <mml:mo>&gt;</mml:mo>
                    <mml:mi mathvariant="italic">h</mml:mi>
                </mml:mrow>
            </mml:math>,
            where 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math>
            is the width and
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml: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.xml"><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"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet.xml"><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.xml"><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"><a id="seealso"></a><h2>See Also</h2><p>
        <a class="citerefentry" href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,
        <a class="citerefentry" href="glBindTexture.xml"><span class="citerefentry"><span class="refentrytitle">glBindTexture</span></span></a>,
        <a class="citerefentry" href="glCompressedTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>,
        <a class="citerefentry" href="glCopyTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,
        <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a>,
        <a class="citerefentry" href="glPixelStorei.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStorei</span></span></a>,
        <a class="citerefentry" href="glTexEnv.xml"><span class="citerefentry"><span class="refentrytitle">glTexEnv</span></span></a>,
        <a class="citerefentry" href="glTexParameter.xml"><span class="citerefentry"><span class="refentrytitle">glTexParameter</span></span></a>
        </p></div><div class="refsect1"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 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></body></html>