upstream-man-pages/man2/xhtml/glLogicOp.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>glLogicOp</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glLogicOp"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glLogicOp — specify a logical pixel operation for color index rendering</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">glLogicOp</b>(</code></td><td>GLenum  </td><td><var class="pdparam">opcode</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>opcode</code></em></span></dt><dd><p>
   4                     Specifies a symbolic constant that selects a logical operation.
   5                     The following symbols are accepted:
   6                     <code class="constant">GL_CLEAR</code>,
   7                     <code class="constant">GL_SET</code>,
   8                     <code class="constant">GL_COPY</code>,
   9                     <code class="constant">GL_COPY_INVERTED</code>,
  10                     <code class="constant">GL_NOOP</code>,
  11                     <code class="constant">GL_INVERT</code>,
  12                     <code class="constant">GL_AND</code>,
  13                     <code class="constant">GL_NAND</code>,
  14                     <code class="constant">GL_OR</code>,
  15                     <code class="constant">GL_NOR</code>,
  16                     <code class="constant">GL_XOR</code>,
  17                     <code class="constant">GL_EQUIV</code>,
  18                     <code class="constant">GL_AND_REVERSE</code>,
  19                     <code class="constant">GL_AND_INVERTED</code>,
  20                     <code class="constant">GL_OR_REVERSE</code>, and
  21                     <code class="constant">GL_OR_INVERTED</code>. The initial value is <code class="constant">GL_COPY</code>.
  22                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  23             <code class="function">glLogicOp</code> specifies a logical operation that,
  24             when enabled,
  25             is applied between the incoming color index or RGBA color
  26             and the color index or RGBA color at the corresponding location in the
  27             frame buffer.
  28             To enable or disable the logical operation, call
  29             <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a>
  30             using the symbolic constant <code class="constant">GL_COLOR_LOGIC_OP</code> for RGBA mode or
  31             <code class="constant">GL_INDEX_LOGIC_OP</code> for color index mode. The initial value is
  32             disabled for both operations.
  33         </p><p>
  34         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
  35                         Opcode
  36                         </strong></span></th><th align="left"><span class="bold"><strong>
  37                         Resulting Operation
  38                         </strong></span></th></tr></thead><tbody><tr><td align="left">
  39                         <code class="constant">GL_CLEAR</code>
  40                         </td><td align="center">
  41                         0
  42                         </td></tr><tr><td align="left">
  43                         <code class="constant">GL_SET</code>
  44                         </td><td align="center">
  45                         1
  46                         </td></tr><tr><td align="left">
  47                         <code class="constant">GL_COPY</code>
  48                         </td><td align="center">
  49                         s
  50                         </td></tr><tr><td align="left">
  51                         <code class="constant">GL_COPY_INVERTED</code>
  52                         </td><td align="center">
  53                         ~s
  54                         </td></tr><tr><td align="left">
  55                         <code class="constant">GL_NOOP</code>
  56                         </td><td align="center">
  57                         d
  58                         </td></tr><tr><td align="left">
  59                         <code class="constant">GL_INVERT</code>
  60                         </td><td align="center">
  61                         ~d
  62                         </td></tr><tr><td align="left">
  63                         <code class="constant">GL_AND</code>
  64                         </td><td align="center">
  65                         s &amp; d
  66                         </td></tr><tr><td align="left">
  67                         <code class="constant">GL_NAND</code>
  68                         </td><td align="center">
  69                         ~(s &amp; d)
  70                         </td></tr><tr><td align="left">
  71                         <code class="constant">GL_OR</code>
  72                         </td><td align="center">
  73                         s | d
  74                         </td></tr><tr><td align="left">
  75                         <code class="constant">GL_NOR</code>
  76                         </td><td align="center">
  77                         ~(s | d)
  78                         </td></tr><tr><td align="left">
  79                         <code class="constant">GL_XOR</code>
  80                         </td><td align="center">
  81                         s ^ d
  82                         </td></tr><tr><td align="left">
  83                         <code class="constant">GL_EQUIV</code>
  84                         </td><td align="center">
  85                         ~(s ^ d)
  86                         </td></tr><tr><td align="left">
  87                         <code class="constant">GL_AND_REVERSE</code>
  88                         </td><td align="center">
  89                         s &amp; ~d
  90                         </td></tr><tr><td align="left">
  91                         <code class="constant">GL_AND_INVERTED</code>
  92                         </td><td align="center">
  93                         ~s &amp; d
  94                         </td></tr><tr><td align="left">
  95                         <code class="constant">GL_OR_REVERSE</code>
  96                         </td><td align="center">
  97                         s | ~d
  98                         </td></tr><tr><td align="left">
  99                         <code class="constant">GL_OR_INVERTED</code>
 100                         </td><td align="center">
 101                         ~s | d
 102                         </td></tr></tbody></table></div><p>
 103             <em class="parameter"><code>opcode</code></em> is a symbolic constant chosen from the list above.
 104             In the explanation of the logical operations,
 105             <span class="emphasis"><em>s</em></span> represents the incoming color index and
 106             <span class="emphasis"><em>d</em></span> represents the index in the frame buffer.
 107             Standard C-language operators are used.
 108             As these bitwise operators suggest,
 109             the logical operation is applied independently to each bit pair of the
 110             source and destination indices or colors.
 111         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 112             Color index logical operations are always supported. RGBA logical
 113             operations are supported only if the GL version is 1.1 or greater.
 114         </p><p>
 115             When more than one RGBA color or index buffer is enabled for drawing,
 116             logical operations are performed separately for each enabled buffer,
 117             using for the destination value the contents of that buffer
 118             (see <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>).
 119         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 120             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>opcode</code></em> is not an accepted value.
 121         </p><p>
 122             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glLogicOp</code>
 123             is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
 124             and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 125         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 126             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_LOGIC_OP_MODE</code>.
 127         </p><p>
 128             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_COLOR_LOGIC_OP</code> or <code class="constant">GL_INDEX_LOGIC_OP</code>.
 129         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 130             <a class="citerefentry" href="glAlphaFunc.xml"><span class="citerefentry"><span class="refentrytitle">glAlphaFunc</span></span></a>,
 131             <a class="citerefentry" href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>,
 132             <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>,
 133             <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
 134             <a class="citerefentry" href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a>
 135         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 136             Copyright <span class="trademark"></span>© 1991-2006
 137             Silicon Graphics, Inc. This document is licensed under the SGI
 138             Free Software B License. For details, see
 139             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 140         </p></div></div></body></html>