upstream-doc/man3/xhtml/glLogicOp.xml

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   4 <?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" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glLogicOp</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></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 rendering</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glLogicOp</b>(</code>GLenum <var class="pdparam">opcode</var><code>)</code>;</p></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>
   5                     Specifies a symbolic constant that selects a logical operation.
   6                     The following symbols are accepted:
   7                     <code class="constant">GL_CLEAR</code>,
   8                     <code class="constant">GL_SET</code>,
   9                     <code class="constant">GL_COPY</code>,
  10                     <code class="constant">GL_COPY_INVERTED</code>,
  11                     <code class="constant">GL_NOOP</code>,
  12                     <code class="constant">GL_INVERT</code>,
  13                     <code class="constant">GL_AND</code>,
  14                     <code class="constant">GL_NAND</code>,
  15                     <code class="constant">GL_OR</code>,
  16                     <code class="constant">GL_NOR</code>,
  17                     <code class="constant">GL_XOR</code>,
  18                     <code class="constant">GL_EQUIV</code>,
  19                     <code class="constant">GL_AND_REVERSE</code>,
  20                     <code class="constant">GL_AND_INVERTED</code>,
  21                     <code class="constant">GL_OR_REVERSE</code>, and
  22                     <code class="constant">GL_OR_INVERTED</code>. The initial value is <code class="constant">GL_COPY</code>.
  23                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  24             <code class="function">glLogicOp</code> specifies a logical operation that,
  25             when enabled,
  26             is applied between the incoming RGBA color
  27             and the RGBA color at the corresponding location in the
  28             frame buffer.
  29             To enable or disable the logical operation, call
  30             <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a>
  31             using the symbolic constant <code class="constant">GL_COLOR_LOGIC_OP</code>. The initial value is
  32             disabled.
  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 and
 106             <span class="emphasis"><em>d</em></span> represents the color 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 colors.
 111         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 112             When more than one RGBA color buffer is enabled for drawing,
 113             logical operations are performed separately for each enabled buffer,
 114             using for the destination value the contents of that buffer
 115             (see <a href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>).
 116         </p><p>
 117             Logic operations have no effect on floating point draw buffers. However, if
 118             <code class="constant">GL_COLOR_LOGIC_OP</code> is enabled, blending is still disabled
 119             in this case.
 120         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 121             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>opcode</code></em> is not an accepted value.
 122         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 123             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_LOGIC_OP_MODE</code>.
 124         </p><p>
 125             <a href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_COLOR_LOGIC_OP</code>.
 126         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 127             <a href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>,
 128             <a href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>,
 129             <a href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
 130             <a href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a>
 131         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 132             Copyright <span class="trademark"></span>© 1991-2006
 133             Silicon Graphics, Inc. This document is licensed under the SGI
 134             Free Software B License. For details, see
 135             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 136         </p></div></div></body></html>