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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>glGetTexImage</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><a id="glGetTexImage"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetTexImage — return a texture image</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">glGetTexImage</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>GLenum <var class="pdparam">format</var>, </td></tr><tr><td> </td><td>GLenum <var class="pdparam">type</var>, </td></tr><tr><td> </td><td>GLvoid * <var class="pdparam">img</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 which texture is to be obtained.
                    <code class="constant">GL_TEXTURE_1D</code>, <code class="constant">GL_TEXTURE_2D</code>, <code class="constant">GL_TEXTURE_3D</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>, and
                    <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code> 
                    are accepted.
                </p></dd><dt><span class="term"><em class="parameter"><code>level</code></em></span></dt><dd><p>
                    Specifies the level-of-detail number of the desired image.
                    Level 0 is the base image level.
                    Level 
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                    is the 
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                    mipmap reduction image.
                </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
                    Specifies a pixel format for the returned data.
                    The supported formats are
                    <code class="constant">GL_RED</code>,
                    <code class="constant">GL_GREEN</code>,
                    <code class="constant">GL_BLUE</code>,
                    <code class="constant">GL_ALPHA</code>,
                    <code class="constant">GL_RGB</code>,
                    <code class="constant">GL_BGR</code>,
                    <code class="constant">GL_RGBA</code>,
                    <code class="constant">GL_BGRA</code>,
                    <code class="constant">GL_LUMINANCE</code>, and
                    <code class="constant">GL_LUMINANCE_ALPHA</code>.
                </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
                    Specifies a pixel type for the returned data.
                    The supported types are
                    <code class="constant">GL_UNSIGNED_BYTE</code>,
                    <code class="constant">GL_BYTE</code>,
                    <code class="constant">GL_UNSIGNED_SHORT</code>,
                    <code class="constant">GL_SHORT</code>,
                    <code class="constant">GL_UNSIGNED_INT</code>,
                    <code class="constant">GL_INT</code>,
                    <code class="constant">GL_FLOAT</code>,
                    <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
                    <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
                    <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
                    <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
                    <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
                    <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, and
                    <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>.
                </p></dd><dt><span class="term"><em class="parameter"><code>img</code></em></span></dt><dd><p>
                    Returns the texture image.
                    Should be a pointer to an array of the type specified by <em class="parameter"><code>type</code></em>.
                </p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>
            <code class="function">glGetTexImage</code> returns a texture image into <em class="parameter"><code>img</code></em>.
            <em class="parameter"><code>target</code></em> specifies whether the desired texture image is one specified by
            <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a> (<code class="constant">GL_TEXTURE_1D</code>),
            <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a> (<code class="constant">GL_TEXTURE_2D</code> or any of
            <code class="constant">GL_TEXTURE_CUBE_MAP_*</code>),
            or
            <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> (<code class="constant">GL_TEXTURE_3D</code>).
            <em class="parameter"><code>level</code></em> specifies the level-of-detail number of the desired image.
            <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em> specify the format and type of the desired image array.
            See the reference pages <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a> and <a class="citerefentry" href="glDrawPixels.xml"><span class="citerefentry"><span class="refentrytitle">glDrawPixels</span></span></a>
            for a description of the acceptable values for the <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>
            parameters, respectively.
        </p><p>
            If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target 
            (see <a class="citerefentry" href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a texture image is
            requested, <em class="parameter"><code>img</code></em> is treated as a byte offset into the buffer object's data store.
        </p><p>
            To understand the operation of <code class="function">glGetTexImage</code>, consider the selected internal
            four-component texture image to be an RGBA color buffer the size of the image.
            The semantics of <code class="function">glGetTexImage</code> are then identical to those of <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
            with the exception that no pixel transfer operations are performed,
            when called with the same <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>,
            with <span class="emphasis"><em>x</em></span> and <span class="emphasis"><em>y</em></span> set to 0,
            <span class="emphasis"><em>width</em></span> set to the width of the texture image
            (including border if one was specified),
            and <span class="emphasis"><em>height</em></span> set to 1 for 1D images,
            or to the height of the texture image
            (including border if one was specified)
            for 2D images.
            Because the internal texture image is an RGBA image,
            pixel formats <code class="constant">GL_COLOR_INDEX</code>,
            <code class="constant">GL_STENCIL_INDEX</code>,
            and <code class="constant">GL_DEPTH_COMPONENT</code> are not accepted,
            and pixel type <code class="constant">GL_BITMAP</code> is not accepted.
        </p><p>
            If the selected texture image does not contain four components,
            the following mappings are applied.
            Single-component textures are treated as RGBA buffers with red set
            to the single-component value,
            green set to 0, blue set to 0, and alpha set to 1.
            Two-component textures are treated as RGBA buffers with red set to
            the value of component zero,
            alpha set to the value of component one,
            and green and blue set to 0.
            Finally,
            three-component textures are treated as RGBA buffers with red set to
            component zero,
            green set to component one,
            blue set to component two,
            and alpha set to 1.
        </p><p>
            To determine the required size of <em class="parameter"><code>img</code></em>,
            use <a class="citerefentry" href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> to determine the dimensions of the
            internal texture image,
            then scale the required number of pixels by the storage required for
            each pixel,
            based on <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>.
            Be sure to take the pixel storage parameters into account,
            especially <code class="constant">GL_PACK_ALIGNMENT</code>.
        </p></div><div class="refsect1"><a id="notes"></a><h2>Notes</h2><p>
            If an error is generated,
            no change is made to the contents of <em class="parameter"><code>img</code></em>.
        </p><p>
            The types <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
            <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
            <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
            <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
            <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
            <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
            <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
            <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
            <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
            <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
            <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>,
            <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>,
            and the formats
            <code class="constant">GL_BGR</code>, and <code class="constant">GL_BGRA</code> are available only if the GL version is
            1.2 or greater.
        </p><p>
            For OpenGL versions 1.3 and greater, or when the <code class="code">ARB_multitexture</code> extension is supported, <code class="function">glGetTexImage</code> returns
            the texture image for the active texture unit.
        </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>, <em class="parameter"><code>format</code></em>, or <em class="parameter"><code>type</code></em> is not
            an accepted value.
        </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 
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            is the returned value of <code class="constant">GL_MAX_TEXTURE_SIZE</code>.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is returned if <em class="parameter"><code>type</code></em> is one of
            <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
            <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
            <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
            <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code> and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is returned if <em class="parameter"><code>type</code></em> is one of
            <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
            <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
            <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
            <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
            <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
            <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
            <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
            <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>, and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code>
            or <code class="constant">GL_BGRA</code>.
        </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_PACK_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_PACK_BUFFER</code> target and the data would be packed to the buffer 
            object such that the memory writes required would exceed the data store size.
        </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_PACK_BUFFER</code> target and <em class="parameter"><code>img</code></em> is not evenly divisible 
            into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glGetTexImage</code>
            is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
            and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
        </p></div><div class="refsect1"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_WIDTH</code>
        </p><p>
            <a class="citerefentry" href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_HEIGHT</code>
        </p><p>
            <a class="citerefentry" href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_BORDER</code>
        </p><p>
            <a class="citerefentry" href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_INTERNAL_FORMAT</code>
        </p><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with arguments <code class="constant">GL_PACK_ALIGNMENT</code> and others
        </p><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PIXEL_PACK_BUFFER_BINDING</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="glDrawPixels.xml"><span class="citerefentry"><span class="refentrytitle">glDrawPixels</span></span></a>,
            <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
            <a class="citerefentry" href="glTexEnv.xml"><span class="citerefentry"><span class="refentrytitle">glTexEnv</span></span></a>,
            <a class="citerefentry" href="glTexGen.xml"><span class="citerefentry"><span class="refentrytitle">glTexGen</span></span></a>,
            <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
            <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
            <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
            <a class="citerefentry" href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
            <a class="citerefentry" href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
            <a class="citerefentry" href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</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>© 1991-2006
            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>