upstream-man-pages/man2/xhtml/glGetMinmax.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>glGetMinmax</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetMinmax"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetMinmax — get minimum and maximum pixel values</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">glGetMinmax</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">types</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_MINMAX</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>, all entries in the minmax table that are actually
   8                     returned are reset to their initial values.  (Other entries are unaltered.)
   9                     If <code class="constant">GL_FALSE</code>, the minmax table is unaltered.
  10                 </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
  11                     The format of the data 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>types</code></em></span></dt><dd><p>
  24                     The type of the data 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 values.
  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">glGetMinmax</code> returns the accumulated minimum and maximum pixel values (computed on a
  51             per-component basis) in a one-dimensional image of width 2.  The first set
  52             of return values are the minima, and the second set of return values
  53             are the maxima.
  54             The format of the return values is determined by <em class="parameter"><code>format</code></em>, and their type is
  55             determined by <em class="parameter"><code>types</code></em>.
  56         </p><p>
  57             If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
  58             (see <a class="citerefentry" href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while minimum and maximum pixel values are
  59             requested, <em class="parameter"><code>values</code></em> is treated as a byte offset into the buffer object's data store.
  60         </p><p>
  61             No pixel transfer operations are performed on the return values, but pixel
  62             storage modes that are applicable to one-dimensional images are performed.
  63             Color components that are requested in the specified <em class="parameter"><code>format</code></em>, but that
  64             are not included in the internal format of the minmax table, are
  65             returned as zero.  The assignment of internal color components to the
  66             components requested by <em class="parameter"><code>format</code></em> are as follows:
  67         </p><p>
  68         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
  69                         Internal Component
  70                         </strong></span></th><th align="left"><span class="bold"><strong>
  71                         Resulting Component
  72                         </strong></span></th></tr></thead><tbody><tr><td align="left">
  73                         Red
  74                         </td><td align="left">
  75                         Red
  76                         </td></tr><tr><td align="left">
  77                         Green
  78                         </td><td align="left">
  79                         Green
  80                         </td></tr><tr><td align="left">
  81                         Blue
  82                         </td><td align="left">
  83                         Blue
  84                         </td></tr><tr><td align="left">
  85                         Alpha
  86                         </td><td align="left">
  87                         Alpha
  88                         </td></tr><tr><td align="left">
  89                         Luminance
  90                         </td><td align="left">
  91                         Red
  92                         </td></tr></tbody></table></div><p>
  93             If <em class="parameter"><code>reset</code></em> is <code class="constant">GL_TRUE</code>, the minmax table entries corresponding
  94             to the return values are reset to their initial
  95             values.  Minimum and maximum values that are not returned are not
  96             modified, even if <em class="parameter"><code>reset</code></em> is <code class="constant">GL_TRUE</code>.
  97         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
  98             <code class="function">glGetMinmax</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>
  99             is called with an argument of <code class="constant">GL_EXTENSIONS</code>.
 100         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 101             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not <code class="constant">GL_MINMAX</code>.
 102         </p><p>
 103             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is not one of the allowable
 104             values.
 105         </p><p>
 106             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>types</code></em> is not one of the allowable
 107             values.
 108         </p><p>
 109             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>types</code></em> is one of
 110             <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
 111             <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
 112             <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
 113             <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
 114             and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
 115         </p><p>
 116             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>types</code></em> is one of
 117             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
 118             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
 119             <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
 120             <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
 121             <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
 122             <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
 123             <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
 124             <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
 125             and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>.
 126         </p><p>
 127             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 128             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
 129         </p><p>
 130             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 131             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
 132             object such that the memory writes required would exceed the data store size.
 133         </p><p>
 134             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 135             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>values</code></em> is not evenly divisible
 136             into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
 137         </p><p>
 138             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glGetMinmax</code> is executed
 139             between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding
 140             execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 141         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 142             <a class="citerefentry" href="glGetMinmaxParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetMinmaxParameter</span></span></a>
 143         </p><p>
 144             <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>
 145         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 146             <a class="citerefentry" href="glMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glMinmax</span></span></a>,
 147             <a class="citerefentry" href="glResetMinmax.xml"><span class="citerefentry"><span class="refentrytitle">glResetMinmax</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>