upstream-man-pages/man2/glReadBuffer.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glReadBuffer">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glReadBuffer</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glReadBuffer</refname>
  17         <refpurpose>select a color buffer source for pixels</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glReadBuffer</function></funcdef>
  23                 <paramdef>GLenum <parameter>mode</parameter></paramdef>
  24             </funcprototype>
  25         </funcsynopsis>
  26     </refsynopsisdiv>
  27     <refsect1 id="parameters"><title>Parameters</title>
  28         <variablelist>
  29         <varlistentry>
  30             <term><parameter>mode</parameter></term>
  31             <listitem>
  32                 <para>
  33                     Specifies a color buffer.
  34                     Accepted values are
  35                     <constant>GL_FRONT_LEFT</constant>,
  36                     <constant>GL_FRONT_RIGHT</constant>,
  37                     <constant>GL_BACK_LEFT</constant>,
  38                     <constant>GL_BACK_RIGHT</constant>,
  39                     <constant>GL_FRONT</constant>,
  40                     <constant>GL_BACK</constant>,
  41                     <constant>GL_LEFT</constant>,
  42                     <constant>GL_RIGHT</constant>, and
  43                     <constant>GL_AUX</constant><emphasis>i</emphasis>,
  44                     where <emphasis>i</emphasis> is between 0 and the value of <constant>GL_AUX_BUFFERS</constant> minus 1.
  45                 </para>
  46             </listitem>
  47         </varlistentry>
  48         </variablelist>
  49     </refsect1>
  50     <refsect1 id="description"><title>Description</title>
  51         <para>
  52             <function>glReadBuffer</function> specifies a color buffer as the source for subsequent
  53             <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
  54             <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
  55             <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>, and
  56             <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry> commands.
  57             <parameter>mode</parameter> accepts one of twelve or more predefined values.
  58             (<constant>GL_AUX0</constant> through <constant>GL_AUX3</constant> are always defined.)
  59             In a fully configured system,
  60             <constant>GL_FRONT</constant>,
  61             <constant>GL_LEFT</constant>, and
  62             <constant>GL_FRONT_LEFT</constant> all name the front left buffer,
  63             <constant>GL_FRONT_RIGHT</constant> and
  64             <constant>GL_RIGHT</constant> name the front right buffer, and
  65             <constant>GL_BACK_LEFT</constant> and
  66             <constant>GL_BACK</constant> name the back left buffer.
  67         </para>
  68         <para>
  69             Nonstereo double-buffered configurations have only a front left and a
  70             back left buffer.
  71             Single-buffered configurations have a front left and a front right
  72             buffer if stereo, and only a front left buffer if nonstereo.
  73             It is an error to specify a nonexistent buffer to <function>glReadBuffer</function>.
  74         </para>
  75         <para>
  76             <parameter>mode</parameter> is initially <constant>GL_FRONT</constant> in single-buffered configurations
  77             and <constant>GL_BACK</constant> in double-buffered configurations.
  78         </para>
  79     </refsect1>
  80     <refsect1 id="errors"><title>Errors</title>
  81         <para>
  82             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of the twelve
  83             (or more) accepted values.
  84         </para>
  85         <para>
  86             <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>mode</parameter> specifies a buffer
  87             that does not exist.
  88         </para>
  89         <para>
  90             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glReadBuffer</function>
  91             is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
  92             and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
  93         </para>
  94     </refsect1>
  95     <refsect1 id="associatedgets"><title>Associated Gets</title>
  96         <para>
  97             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_READ_BUFFER</constant>
  98         </para>
  99     </refsect1>
 100     <refsect1 id="seealso"><title>See Also</title>
 101         <para>
 102             <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
 103             <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
 104             <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
 105             <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
 106             <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
 107             <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
 108             <citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>,
 109             <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>
 110         </para>
 111     </refsect1>
 112     <refsect1 id="Copyright"><title>Copyright</title>
 113         <para>
 114             Copyright <trademark class="copyright"></trademark> 1991-2006
 115             Silicon Graphics, Inc. This document is licensed under the SGI
 116             Free Software B License. For details, see
 117             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 118         </para>
 119     </refsect1>
 120 </refentry>