upstream-doc/man2/xhtml/glCopyColorTable.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>glCopyColorTable</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glCopyColorTable"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glCopyColorTable — copy pixels into a color 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">glCopyColorTable</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">internalformat</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">x</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">y</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">width</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 color table target. Must be
   5                     <code class="constant">GL_COLOR_TABLE</code>,
   6                     <code class="constant">GL_POST_CONVOLUTION_COLOR_TABLE</code>,
   7                     or <code class="constant">GL_POST_COLOR_MATRIX_COLOR_TABLE</code>.
   8                 </p></dd><dt><span class="term"><em class="parameter"><code>internalformat</code></em></span></dt><dd><p>
   9                     The internal storage format of the texture image.
  10                     Must be one of the following symbolic constants:
  11                     <code class="constant">GL_ALPHA</code>,
  12                     <code class="constant">GL_ALPHA4</code>,
  13                     <code class="constant">GL_ALPHA8</code>,
  14                     <code class="constant">GL_ALPHA12</code>,
  15                     <code class="constant">GL_ALPHA16</code>,
  16                     <code class="constant">GL_LUMINANCE</code>,
  17                     <code class="constant">GL_LUMINANCE4</code>,
  18                     <code class="constant">GL_LUMINANCE8</code>,
  19                     <code class="constant">GL_LUMINANCE12</code>,
  20                     <code class="constant">GL_LUMINANCE16</code>,
  21                     <code class="constant">GL_LUMINANCE_ALPHA</code>,
  22                     <code class="constant">GL_LUMINANCE4_ALPHA4</code>,
  23                     <code class="constant">GL_LUMINANCE6_ALPHA2</code>,
  24                     <code class="constant">GL_LUMINANCE8_ALPHA8</code>,
  25                     <code class="constant">GL_LUMINANCE12_ALPHA4</code>,
  26                     <code class="constant">GL_LUMINANCE12_ALPHA12</code>,
  27                     <code class="constant">GL_LUMINANCE16_ALPHA16</code>,
  28                     <code class="constant">GL_INTENSITY</code>,
  29                     <code class="constant">GL_INTENSITY4</code>,
  30                     <code class="constant">GL_INTENSITY8</code>,
  31                     <code class="constant">GL_INTENSITY12</code>,
  32                     <code class="constant">GL_INTENSITY16</code>,
  33                     <code class="constant">GL_R3_G3_B2</code>,
  34                     <code class="constant">GL_RGB</code>,
  35                     <code class="constant">GL_RGB4</code>,
  36                     <code class="constant">GL_RGB5</code>,
  37                     <code class="constant">GL_RGB8</code>,
  38                     <code class="constant">GL_RGB10</code>,
  39                     <code class="constant">GL_RGB12</code>,
  40                     <code class="constant">GL_RGB16</code>,
  41                     <code class="constant">GL_RGBA</code>,
  42                     <code class="constant">GL_RGBA2</code>,
  43                     <code class="constant">GL_RGBA4</code>,
  44                     <code class="constant">GL_RGB5_A1</code>,
  45                     <code class="constant">GL_RGBA8</code>,
  46                     <code class="constant">GL_RGB10_A2</code>,
  47                     <code class="constant">GL_RGBA12</code>, or
  48                     <code class="constant">GL_RGBA16</code>.
  49                 </p></dd><dt><span class="term"><em class="parameter"><code>x</code></em></span></dt><dd><p>
  50                     The x coordinate of the lower-left corner of the pixel rectangle
  51                     to be transferred to the color table.
  52                 </p></dd><dt><span class="term"><em class="parameter"><code>y</code></em></span></dt><dd><p>
  53                     The y coordinate of the lower-left corner of the pixel rectangle
  54                     to be transferred to the color table.
  55                 </p></dd><dt><span class="term"><em class="parameter"><code>width</code></em></span></dt><dd><p>
  56                     The width of the pixel rectangle.
  57                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  58             <code class="function">glCopyColorTable</code> loads a color table with pixels from the current
  59             <code class="constant">GL_READ_BUFFER</code> (rather than from main memory, as is the case for
  60             <a class="citerefentry" href="glColorTable.xml"><span class="citerefentry"><span class="refentrytitle">glColorTable</span></span></a>).
  61         </p><p>
  62             The screen-aligned pixel rectangle with lower-left corner at (<em class="parameter"><code>x</code></em>,\ <em class="parameter"><code>y</code></em>)
  63             having width <em class="parameter"><code>width</code></em> and height 1
  64             is loaded into the color table. If any pixels within
  65             this region are outside the window that is associated with the GL
  66             context, the values obtained for those pixels are undefined.
  67         </p><p>
  68             The pixels in the rectangle are processed just as if
  69             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a> were called, with <em class="parameter"><code>internalformat</code></em> set to RGBA,
  70             but processing stops after the final conversion to RGBA.
  71         </p><p>
  72             The four scale parameters and the four bias parameters that are defined
  73             for the table are then used to scale and bias the R, G, B, and A components
  74             of each pixel. The scale and bias parameters are set by calling
  75             <a class="citerefentry" href="glColorTableParameter.xml"><span class="citerefentry"><span class="refentrytitle">glColorTableParameter</span></span></a>.
  76         </p><p>
  77             Next, the R, G, B, and A values are clamped to the range
  78             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  79
  80                 <mml:mfenced open="[" close="]">
  81                     <mml:mn>0</mml:mn>
  82                     <mml:mn>1</mml:mn>
  83                 </mml:mfenced>
  84             </mml:math>.
  85             Each pixel is then converted to the internal format specified by
  86             <em class="parameter"><code>internalformat</code></em>. This conversion simply maps the component values of the pixel (R, G, B,
  87             and A) to the values included in the internal format (red, green, blue,
  88             alpha, luminance, and intensity).  The mapping is as follows:
  89         </p><p>
  90         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
  91                         Internal Format
  92                         </strong></span></th><th align="center"><span class="bold"><strong>
  93                         Red
  94                         </strong></span></th><th align="center"><span class="bold"><strong>
  95                         Green
  96                         </strong></span></th><th align="center"><span class="bold"><strong>
  97                         Blue
  98                         </strong></span></th><th align="center"><span class="bold"><strong>
  99                         Alpha
 100                         </strong></span></th><th align="center"><span class="bold"><strong>
 101                         Luminance
 102                         </strong></span></th><th align="center"><span class="bold"><strong>
 103                         Intensity
 104                         </strong></span></th></tr></thead><tbody><tr><td align="left">
 105                         <code class="constant">GL_ALPHA</code>
 106                         </td><td align="center">
 107                         </td><td align="center">
 108                         </td><td align="center">
 109                         </td><td align="center">
 110                         A
 111                         </td><td align="center">
 112                         </td><td align="center">
 113
 114                         </td></tr><tr><td align="left">
 115                         <code class="constant">GL_LUMINANCE</code>
 116                         </td><td align="center">
 117                         </td><td align="center">
 118                         </td><td align="center">
 119                         </td><td align="center">
 120                         </td><td align="center">
 121                         R
 122                         </td><td align="center">
 123
 124                         </td></tr><tr><td align="left">
 125                         <code class="constant">GL_LUMINANCE_ALPHA</code>
 126                         </td><td align="center">
 127                         </td><td align="center">
 128                         </td><td align="center">
 129                         </td><td align="center">
 130                         A
 131                         </td><td align="center">
 132                         R
 133                         </td><td align="center">
 134
 135                         </td></tr><tr><td align="left">
 136                         <code class="constant">GL_INTENSITY</code>
 137                         </td><td align="center">
 138                         </td><td align="center">
 139                         </td><td align="center">
 140                         </td><td align="center">
 141                         </td><td align="center">
 142                         </td><td align="center">
 143                         R
 144                         </td></tr><tr><td align="left">
 145                         <code class="constant">GL_RGB</code>
 146                         </td><td align="center">
 147                         R
 148                         </td><td align="center">
 149                         G
 150                         </td><td align="center">
 151                         B
 152                         </td><td align="center">
 153                         </td><td align="center">
 154                         </td><td align="center">
 155
 156                         </td></tr><tr><td align="left">
 157                         <code class="constant">GL_RGBA</code>
 158                         </td><td align="center">
 159                         R
 160                         </td><td align="center">
 161                         G
 162                         </td><td align="center">
 163                         B
 164                         </td><td align="center">
 165                         A
 166                         </td><td align="center">
 167                         </td><td align="center">
 168
 169                         </td></tr></tbody></table></div><p>
 170             Finally, the red, green, blue, alpha, luminance, and/or intensity components of
 171             the resulting pixels are stored in the color table.
 172             They form a one-dimensional table with indices in the range
 173             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 174
 175                 <mml:mfenced open="[" close="]">
 176                     <mml:mn>0</mml:mn>
 177                     <mml:mrow>
 178                         <mml:mi mathvariant="italic">width</mml:mi>
 179                         <mml:mo>-</mml:mo>
 180                         <mml:mn>1</mml:mn>
 181                     </mml:mrow>
 182                 </mml:mfenced>
 183             </mml:math>.
 184         </p><p>
 185         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 186             <code class="function">glCopyColorTable</code> is available only if <code class="code">ARB_imaging</code> is returned from calling
 187             <a class="citerefentry" href="glGetString.xml"><span class="citerefentry"><span class="refentrytitle">glGetString</span></span></a> with an argument of <code class="constant">GL_EXTENSIONS</code>.
 188         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 189             <code class="constant">GL_INVALID_ENUM</code> is generated when <em class="parameter"><code>target</code></em> is not one of the
 190             allowable values.
 191         </p><p>
 192             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>width</code></em> is less than zero.
 193         </p><p>
 194             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>internalformat</code></em> is not one of the
 195             allowable values.
 196         </p><p>
 197             <code class="constant">GL_TABLE_TOO_LARGE</code> is generated if the requested color table
 198             is too large to be supported by the implementation.
 199         </p><p>
 200             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glCopyColorTable</code> is executed
 201             between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding
 202             execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 203         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 204             <a class="citerefentry" href="glGetColorTable.xml"><span class="citerefentry"><span class="refentrytitle">glGetColorTable</span></span></a>,
 205             <a class="citerefentry" href="glGetColorTableParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetColorTableParameter</span></span></a>
 206         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 207             <a class="citerefentry" href="glColorTable.xml"><span class="citerefentry"><span class="refentrytitle">glColorTable</span></span></a>,
 208             <a class="citerefentry" href="glColorTableParameter.xml"><span class="citerefentry"><span class="refentrytitle">glColorTableParameter</span></span></a>,
 209             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>
 210         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 211             Copyright <span class="trademark"></span>© 1991-2006
 212             Silicon Graphics, Inc. This document is licensed under the SGI
 213             Free Software B License. For details, see
 214             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 215         </p></div></div></body></html>