upstream-man-pages/man2/xhtml/glReadBuffer.xml

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
   2 <!-- saved from url=(0013)about:internet -->
   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>glReadBuffer</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glReadBuffer"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glReadBuffer — select a color buffer source for pixels</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">glReadBuffer</b>(</code></td><td>GLenum  </td><td><var class="pdparam">mode</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>mode</code></em></span></dt><dd><p>
   4                     Specifies a color buffer.
   5                     Accepted values are
   6                     <code class="constant">GL_FRONT_LEFT</code>,
   7                     <code class="constant">GL_FRONT_RIGHT</code>,
   8                     <code class="constant">GL_BACK_LEFT</code>,
   9                     <code class="constant">GL_BACK_RIGHT</code>,
  10                     <code class="constant">GL_FRONT</code>,
  11                     <code class="constant">GL_BACK</code>,
  12                     <code class="constant">GL_LEFT</code>,
  13                     <code class="constant">GL_RIGHT</code>, and
  14                     <code class="constant">GL_AUX</code><span class="emphasis"><em>i</em></span>,
  15                     where <span class="emphasis"><em>i</em></span> is between 0 and the value of <code class="constant">GL_AUX_BUFFERS</code> minus 1.
  16                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  17             <code class="function">glReadBuffer</code> specifies a color buffer as the source for subsequent
  18             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>, <a class="citerefentry" href="glCopyTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage1D</span></span></a>, <a class="citerefentry" href="glCopyTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>,
  19             <a class="citerefentry" href="glCopyTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage1D</span></span></a>, <a class="citerefentry" href="glCopyTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,
  20             <a class="citerefentry" href="glCopyTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage3D</span></span></a>, and
  21             <a class="citerefentry" href="glCopyPixels.xml"><span class="citerefentry"><span class="refentrytitle">glCopyPixels</span></span></a> commands.
  22             <em class="parameter"><code>mode</code></em> accepts one of twelve or more predefined values.
  23             (<code class="constant">GL_AUX0</code> through <code class="constant">GL_AUX3</code> are always defined.)
  24             In a fully configured system,
  25             <code class="constant">GL_FRONT</code>,
  26             <code class="constant">GL_LEFT</code>, and
  27             <code class="constant">GL_FRONT_LEFT</code> all name the front left buffer,
  28             <code class="constant">GL_FRONT_RIGHT</code> and
  29             <code class="constant">GL_RIGHT</code> name the front right buffer, and
  30             <code class="constant">GL_BACK_LEFT</code> and
  31             <code class="constant">GL_BACK</code> name the back left buffer.
  32         </p><p>
  33             Nonstereo double-buffered configurations have only a front left and a
  34             back left buffer.
  35             Single-buffered configurations have a front left and a front right
  36             buffer if stereo, and only a front left buffer if nonstereo.
  37             It is an error to specify a nonexistent buffer to <code class="function">glReadBuffer</code>.
  38         </p><p>
  39             <em class="parameter"><code>mode</code></em> is initially <code class="constant">GL_FRONT</code> in single-buffered configurations
  40             and <code class="constant">GL_BACK</code> in double-buffered configurations.
  41         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  42             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>mode</code></em> is not one of the twelve
  43             (or more) accepted values.
  44         </p><p>
  45             <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>mode</code></em> specifies a buffer
  46             that does not exist.
  47         </p><p>
  48             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glReadBuffer</code>
  49             is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
  50             and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
  51         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
  52             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_READ_BUFFER</code>
  53         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  54             <a class="citerefentry" href="glCopyPixels.xml"><span class="citerefentry"><span class="refentrytitle">glCopyPixels</span></span></a>,
  55             <a class="citerefentry" href="glCopyTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage1D</span></span></a>,
  56             <a class="citerefentry" href="glCopyTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>,
  57             <a class="citerefentry" href="glCopyTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage1D</span></span></a>,
  58             <a class="citerefentry" href="glCopyTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,
  59             <a class="citerefentry" href="glCopyTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage3D</span></span></a>,
  60             <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>,
  61             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>
  62         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  63             Copyright <span class="trademark"></span>© 1991-2006
  64             Silicon Graphics, Inc. This document is licensed under the SGI
  65             Free Software B License. For details, see
  66             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
  67         </p></div></div></body></html>