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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>glGetSeparableFilter</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetSeparableFilter"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetSeparableFilter — get separable convolution filter kernel images</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glGetSeparableFilter</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">format</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">type</var>, </td></tr><tr><td> </td><td>GLvoid *  </td><td><var class="pdparam">row</var>, </td></tr><tr><td> </td><td>GLvoid *  </td><td><var class="pdparam">column</var>, </td></tr><tr><td> </td><td>GLvoid *  </td><td><var class="pdparam">span</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>
                    The separable filter to be retrieved.
                    Must be
                    <code class="constant">GL_SEPARABLE_2D</code>.
                </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
                    Format of the output images.
                    Must be one of
                    <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>, or
                    <code class="constant">GL_LUMINANCE_ALPHA</code>.
                </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
                    Data type of components in the output images.
                    Symbolic constants
                    <code class="constant">GL_UNSIGNED_BYTE</code>,
                    <code class="constant">GL_BYTE</code>,
                    <code class="constant">GL_BITMAP</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>
                    are accepted.
                </p></dd><dt><span class="term"><em class="parameter"><code>row</code></em></span></dt><dd><p>
                    Pointer to storage for the row filter image.
                </p></dd><dt><span class="term"><em class="parameter"><code>column</code></em></span></dt><dd><p>
                    Pointer to storage for the column filter image.
                </p></dd><dt><span class="term"><em class="parameter"><code>span</code></em></span></dt><dd><p>
                    Pointer to storage for the span filter image (currently unused).
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">glGetSeparableFilter</code> returns the two one-dimensional filter kernel images for the
            current separable 2D convolution filter.
            The row image is placed in <em class="parameter"><code>row</code></em> and the column image is placed in
            <em class="parameter"><code>column</code></em> according to the specifications in <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>.
            (In the current implementation, <em class="parameter"><code>span</code></em> is not affected in any way.)
            No pixel transfer operations are performed on the images, but the relevant
            pixel storage modes are applied.
        </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 separable convolution filter is
            requested, <em class="parameter"><code>row</code></em>, <em class="parameter"><code>column</code></em>, and <em class="parameter"><code>span</code></em> are treated as a byte offset into the buffer object's data store.
        </p><p>
            Color components that are present in <em class="parameter"><code>format</code></em> but not included in the
            internal format of the filters are returned as zero.
            The assignments of internal color components to the components of <em class="parameter"><code>format</code></em>
            are as follows:
        </p><p>
        </p><div class="informaltable"><table border="1"><colgroup><col align="center" /><col align="center" /></colgroup><thead><tr><th align="center"><span class="bold"><strong>
                        Internal Component
                        </strong></span></th><th align="center"><span class="bold"><strong>
                        Resulting Component
                        </strong></span></th></tr></thead><tbody><tr><td align="left">
                        Red
                        </td><td align="left">
                        Red
                        </td></tr><tr><td align="left">
                        Green
                        </td><td align="left">
                        Green
                        </td></tr><tr><td align="left">
                        Blue
                        </td><td align="left">
                        Blue
                        </td></tr><tr><td align="left">
                        Alpha
                        </td><td align="left">
                        Alpha
                        </td></tr><tr><td align="left">
                        Luminance
                        </td><td align="left">
                        Red
                        </td></tr><tr><td align="left">
                        Intensity
                        </td><td align="left">
                        Red
                        </td></tr></tbody></table></div><p>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
            <code class="function">glGetSeparableFilter</code> is present only if <code class="code">ARB_imaging</code> is returned when <a class="citerefentry" href="glGetString.xml"><span class="citerefentry"><span class="refentrytitle">glGetString</span></span></a>
            is called with an argument of <code class="constant">GL_EXTENSIONS</code>.
        </p><p>
            Non-separable 2D filters must be retrieved with <a class="citerefentry" href="glGetConvolutionFilter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionFilter</span></span></a>.
        </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>target</code></em> is not <code class="constant">GL_SEPARABLE_2D</code>.
        </p><p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is not one of the allowable
            values.
        </p><p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>type</code></em> is not one of the allowable
            values.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated 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 generated 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> nor <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>row</code></em> or <em class="parameter"><code>column</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">glGetSeparableFilter</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" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGetConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionParameter</span></span></a>
        </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" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a class="citerefentry" href="glGetConvolutionFilter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionFilter</span></span></a>,
            <a class="citerefentry" href="glConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionParameter</span></span></a>,
            <a class="citerefentry" href="glSeparableFilter2D.xml"><span class="citerefentry"><span class="refentrytitle">glSeparableFilter2D</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><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>
