upstream-man-pages/man2/xhtml/glGetConvolutionFilter.xml

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   3 <?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>glGetConvolutionFilter</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetConvolutionFilter"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetConvolutionFilter — get current 1D or 2D convolution filter kernel</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">glGetConvolutionFilter</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">image</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>
   4                     The filter to be retrieved.
   5                     Must be one of
   6                     <code class="constant">GL_CONVOLUTION_1D</code> or
   7                     <code class="constant">GL_CONVOLUTION_2D</code>.
   8                 </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
   9                     Format of the output image.
  10                     Must be one of
  11                     <code class="constant">GL_RED</code>,
  12                     <code class="constant">GL_GREEN</code>,
  13                     <code class="constant">GL_BLUE</code>,
  14                     <code class="constant">GL_ALPHA</code>,
  15                     <code class="constant">GL_RGB</code>,
  16                     <code class="constant">GL_BGR</code>,
  17                     <code class="constant">GL_RGBA</code>,
  18                     <code class="constant">GL_BGRA</code>,
  19                     <code class="constant">GL_LUMINANCE</code>, or
  20                     <code class="constant">GL_LUMINANCE_ALPHA</code>.
  21                 </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
  22                     Data type of components in the output image.
  23                     Symbolic constants
  24                     <code class="constant">GL_UNSIGNED_BYTE</code>,
  25                     <code class="constant">GL_BYTE</code>,
  26                     <code class="constant">GL_BITMAP</code>,
  27                     <code class="constant">GL_UNSIGNED_SHORT</code>,
  28                     <code class="constant">GL_SHORT</code>,
  29                     <code class="constant">GL_UNSIGNED_INT</code>,
  30                     <code class="constant">GL_INT</code>,
  31                     <code class="constant">GL_FLOAT</code>,
  32                     <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
  33                     <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
  34                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
  35                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
  36                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
  37                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
  38                     <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
  39                     <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
  40                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
  41                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
  42                     <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, and
  43                     <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
  44                     are accepted.
  45                 </p></dd><dt><span class="term"><em class="parameter"><code>image</code></em></span></dt><dd><p>
  46                     Pointer to storage for the output image.
  47                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  48             <code class="function">glGetConvolutionFilter</code> returns the current 1D or 2D convolution filter kernel as an image.
  49             The one- or two-dimensional image is placed in <em class="parameter"><code>image</code></em> according to the
  50             specifications in <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>.
  51             No pixel transfer operations are performed on this image, but the relevant
  52             pixel storage modes are applied.
  53         </p><p>
  54             If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
  55             (see <a class="citerefentry" href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a convolution filter is
  56             requested, <em class="parameter"><code>image</code></em> is treated as a byte offset into the buffer object's data store.
  57         </p><p>
  58             Color components that are present in <em class="parameter"><code>format</code></em> but not included in the
  59             internal format of the filter are returned as zero.
  60             The assignments of internal color components to the components of <em class="parameter"><code>format</code></em>
  61             are as follows.
  62         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
  63                         Internal Component
  64                         </strong></span></th><th align="left"><span class="bold"><strong>
  65                         Resulting Component
  66                         </strong></span></th></tr></thead><tbody><tr><td align="left">
  67                         Red
  68                         </td><td align="left">
  69                         Red
  70                         </td></tr><tr><td align="left">
  71                         Green
  72                         </td><td align="left">
  73                         Green
  74                         </td></tr><tr><td align="left">
  75                         Blue
  76                         </td><td align="left">
  77                         Blue
  78                         </td></tr><tr><td align="left">
  79                         Alpha
  80                         </td><td align="left">
  81                         Alpha
  82                         </td></tr><tr><td align="left">
  83                         Luminance
  84                         </td><td align="left">
  85                         Red
  86                         </td></tr><tr><td align="left">
  87                         Intensity
  88                         </td><td align="left">
  89                         Red
  90                         </td></tr></tbody></table></div><p>
  91         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  92             <code class="function">glGetConvolutionFilter</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>
  93             is called with an argument of <code class="constant">GL_EXTENSIONS</code>.
  94         </p><p>
  95             The current separable 2D filter must be retrieved with
  96             <a class="citerefentry" href="glGetSeparableFilter.xml"><span class="citerefentry"><span class="refentrytitle">glGetSeparableFilter</span></span></a> rather than <code class="function">glGetConvolutionFilter</code>.
  97         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  98             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not one of the allowable
  99             values.
 100         </p><p>
 101             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is not one of the allowable
 102             values.
 103         </p><p>
 104             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>type</code></em> is not one of the allowable
 105             values.
 106         </p><p>
 107             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
 108             <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
 109             <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
 110             <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
 111             <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
 112             and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
 113         </p><p>
 114             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
 115             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
 116             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
 117             <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
 118             <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
 119             <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
 120             <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
 121             <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
 122             <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
 123             and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>.
 124         </p><p>
 125             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 126             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
 127         </p><p>
 128             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 129             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
 130             object such that the memory writes required would exceed the data store size.
 131         </p><p>
 132             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 133             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>image</code></em> is not evenly divisible
 134             into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
 135         </p><p>
 136             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glGetConvolutionFilter</code> is executed
 137             between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding
 138             execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 139         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 140             <a class="citerefentry" href="glGetConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionParameter</span></span></a>
 141         </p><p>
 142             <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>
 143         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 144             <a class="citerefentry" href="glGetSeparableFilter.xml"><span class="citerefentry"><span class="refentrytitle">glGetSeparableFilter</span></span></a>,
 145             <a class="citerefentry" href="glConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionParameter</span></span></a>,
 146             <a class="citerefentry" href="glConvolutionFilter1D.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionFilter1D</span></span></a>,
 147             <a class="citerefentry" href="glConvolutionFilter2D.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionFilter2D</span></span></a>
 148         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 149             Copyright <span class="trademark"></span>© 1991-2006
 150             Silicon Graphics, Inc. This document is licensed under the SGI
 151             Free Software B License. For details, see
 152             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 153         </p></div></div></body></html>