glCompressedTexImage2D.xhtml

<div class="refentry" lang="en" xml:lang="en"><a id="glCompressedTexImage2D"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glCompressedTexImage2D — specify a two-dimensional texture image 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">glCompressedTexImage2D</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>GLenum  </td><td><var class="pdparam">internalformat</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>GLint  </td><td><var class="pdparam">border</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_PROXY_TEXTURE_2D</code>,
                    <code class="constant">GL_TEXTURE_1D_ARRAY</code>, <code class="constant">GL_PROXY_TEXTURE_1D_ARRAY</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>,
                    <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>, or
                    <code class="constant">GL_PROXY_TEXTURE_CUBE_MAP</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>internalformat</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>width</code></em></span></dt><dd><p>
                    Specifies the width of the texture image.
                    All implementations support 2D texture images that are at least 64 texels
                    wide and cube-mapped texture images that are at least 16 texels wide.
                </p></dd><dt><span class="term"><em class="parameter"><code>height</code></em></span></dt><dd><p>
                    Specifies the height of the texture image.
                    All implementations support 2D texture images that are at least 64 texels
                    high and cube-mapped texture images that are at least 16 texels high.
                </p></dd><dt><span class="term"><em class="parameter"><code>border</code></em></span></dt><dd><p>
                    This value must be 0.
                </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">glCompressedTexImage2D</code> loads a previously defined, and retrieved, compressed two-dimensional
            texture image if <em class="parameter"><code>target</code></em> is <code class="constant">GL_TEXTURE_2D</code>, or one of the
            cube map faces such as <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>.
            (see <a href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>).
        </p><p>
            If <em class="parameter"><code>target</code></em> is <code class="constant">GL_TEXTURE_1D_ARRAY</code>, <em class="parameter"><code>data</code></em>
            is treated as an array of compressed 1D textures.
        </p><p>
            If <em class="parameter"><code>target</code></em> is <code class="constant">GL_PROXY_TEXTURE_2D</code>, <code class="constant">GL_PROXY_TEXTURE_1D_ARRAY</code>
            or <code class="constant">GL_PROXY_TEXTURE_CUBE_MAP</code>, no data is read from <em class="parameter"><code>data</code></em>, but
            all of the texture image state is recalculated, checked for consistency,
            and checked against the implementation's capabilities.  If the
            implementation cannot handle a texture of the requested texture size, it
            sets all of the image state to 0, but does not generate an error (see
            <a href="glGetError"><span class="citerefentry"><span class="refentrytitle">glGetError</span></span></a>). To query for an entire mipmap array,
            use an image array level greater than or equal to 1.
        </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.
            When a texture is loaded with <a href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a> using a generic compressed
            texture format (e.g., <code class="constant">GL_COMPRESSED_RGB</code>), the GL selects from one of
            its extensions supporting compressed textures.  In order to load the
            compressed texture image using <code class="function">glCompressedTexImage2D</code>, query the compressed texture image's
            size and format using <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 not one 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_VALUE</code> is generated if <em class="parameter"><code>border</code></em> is not 0.
        </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="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="glCompressedTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</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="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="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></div>