upstream-man-pages/man2/xhtml/glGetHistogram.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>glGetHistogram</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetHistogram"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetHistogram — get histogram table</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">glGetHistogram</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLboolean  </td><td><var class="pdparam">reset</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">values</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                     Must be
   5                     <code class="constant">GL_HISTOGRAM</code>.
   6                 </p></dd><dt><span class="term"><em class="parameter"><code>reset</code></em></span></dt><dd><p>
   7                     If <code class="constant">GL_TRUE</code>, each component counter that is actually returned
   8                     is reset to zero.  (Other counters are unaffected.)
   9                     If <code class="constant">GL_FALSE</code>, none of the counters in the histogram table is modified.
  10                 </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
  11                     The format of values to be returned in <em class="parameter"><code>values</code></em>.
  12                     Must be one of
  13                     <code class="constant">GL_RED</code>,
  14                     <code class="constant">GL_GREEN</code>,
  15                     <code class="constant">GL_BLUE</code>,
  16                     <code class="constant">GL_ALPHA</code>,
  17                     <code class="constant">GL_RGB</code>,
  18                     <code class="constant">GL_BGR</code>,
  19                     <code class="constant">GL_RGBA</code>,
  20                     <code class="constant">GL_BGRA</code>,
  21                     <code class="constant">GL_LUMINANCE</code>, or
  22                     <code class="constant">GL_LUMINANCE_ALPHA</code>.
  23                 </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
  24                     The type of values to be returned in <em class="parameter"><code>values</code></em>.
  25                     Symbolic constants
  26                     <code class="constant">GL_UNSIGNED_BYTE</code>,
  27                     <code class="constant">GL_BYTE</code>,
  28                     <code class="constant">GL_BITMAP</code>,
  29                     <code class="constant">GL_UNSIGNED_SHORT</code>,
  30                     <code class="constant">GL_SHORT</code>,
  31                     <code class="constant">GL_UNSIGNED_INT</code>,
  32                     <code class="constant">GL_INT</code>,
  33                     <code class="constant">GL_FLOAT</code>,
  34                     <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
  35                     <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
  36                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
  37                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
  38                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
  39                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
  40                     <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
  41                     <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
  42                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
  43                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
  44                     <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, and
  45                     <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
  46                     are accepted.
  47                 </p></dd><dt><span class="term"><em class="parameter"><code>values</code></em></span></dt><dd><p>
  48                     A pointer to storage for the returned histogram table.
  49                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  50             <code class="function">glGetHistogram</code> returns the current histogram table as a one-dimensional image
  51             with the same width as the histogram.
  52             No pixel transfer operations are performed on this image, but pixel storage
  53             modes that are applicable to 1D images are honored.
  54         </p><p>
  55             If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
  56             (see <a class="citerefentry" href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a histogram table is
  57             requested, <em class="parameter"><code>values</code></em> is treated as a byte offset into the buffer object's data store.
  58         </p><p>
  59             Color components that are requested in the specified <em class="parameter"><code>format</code></em>, but which
  60             are not included in the internal format of the histogram, are returned as
  61             zero.
  62             The assignments of internal color components to the components
  63             requested by <em class="parameter"><code>format</code></em> are:
  64         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
  65                         Internal Component
  66                         </strong></span></th><th align="left"><span class="bold"><strong>
  67                         Resulting Component
  68                         </strong></span></th></tr></thead><tbody><tr><td align="left">
  69                         Red
  70                         </td><td align="left">
  71                         Red
  72                         </td></tr><tr><td align="left">
  73                         Green
  74                         </td><td align="left">
  75                         Green
  76                         </td></tr><tr><td align="left">
  77                         Blue
  78                         </td><td align="left">
  79                         Blue
  80                         </td></tr><tr><td align="left">
  81                         Alpha
  82                         </td><td align="left">
  83                         Alpha
  84                         </td></tr><tr><td align="left">
  85                         Luminance
  86                         </td><td align="left">
  87                         Red
  88                         </td></tr></tbody></table></div><p>
  89         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  90             <code class="function">glGetHistogram</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>
  91             is called with an argument of <code class="constant">GL_EXTENSIONS</code>.
  92         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  93             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not <code class="constant">GL_HISTOGRAM</code>.
  94         </p><p>
  95             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is not one of the allowable
  96             values.
  97         </p><p>
  98             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>type</code></em> is not one of the allowable
  99             values.
 100         </p><p>
 101             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
 102             <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
 103             <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
 104             <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
 105             <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
 106             and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
 107         </p><p>
 108             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
 109             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
 110             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
 111             <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
 112             <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
 113             <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
 114             <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
 115             <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
 116             <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
 117             and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>.
 118         </p><p>
 119             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 120             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
 121         </p><p>
 122             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 123             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
 124             object such that the memory writes required would exceed the data store size.
 125         </p><p>
 126             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 127             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>values</code></em> is not evenly divisible
 128             into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
 129         </p><p>
 130             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glGetHistogram</code> is executed
 131             between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding
 132             execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 133         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 134             <a class="citerefentry" href="glGetHistogramParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetHistogramParameter</span></span></a>
 135         </p><p>
 136             <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>
 137         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 138             <a class="citerefentry" href="glHistogram.xml"><span class="citerefentry"><span class="refentrytitle">glHistogram</span></span></a>,
 139             <a class="citerefentry" href="glResetHistogram.xml"><span class="citerefentry"><span class="refentrytitle">glResetHistogram</span></span></a>,
 140         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 141             Copyright <span class="trademark"></span>© 1991-2006
 142             Silicon Graphics, Inc. This document is licensed under the SGI
 143             Free Software B License. For details, see
 144             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 145         </p></div></div></body></html>