upstream-doc/man2/glXCreateContext.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="glXCreateContext">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glXCreateContext</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glXCreateContext</refname>
  17         <refpurpose>create a new GLX rendering context</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>GLXContext <function>glXCreateContext</function></funcdef>
  23                 <paramdef>Display * <parameter>dpy</parameter></paramdef>
  24                 <paramdef>XVisualInfo * <parameter>vis</parameter></paramdef>
  25                 <paramdef>GLXContext <parameter>shareList</parameter></paramdef>
  26                 <paramdef>Bool <parameter>direct</parameter></paramdef>
  27             </funcprototype>
  28         </funcsynopsis>
  29     </refsynopsisdiv>
  30     <!-- eqn: ignoring delim $$ -->
  31     <refsect1 id="parameters"><title>Parameters</title>
  32         <variablelist>
  33         <varlistentry>
  34             <term><parameter>dpy</parameter></term>
  35             <listitem>
  36                 <para>
  37                     Specifies the connection to the X server.
  38                 </para>
  39             </listitem>
  40         </varlistentry>
  41         <varlistentry>
  42             <term><parameter>vis</parameter></term>
  43             <listitem>
  44                 <para>
  45                     Specifies the visual that defines the frame buffer resources available to
  46                     the rendering context.
  47                     It is a pointer to an <constant>XVisualInfo</constant> structure,
  48                     not a visual ID or a pointer to a <constant>Visual</constant>.
  49                 </para>
  50             </listitem>
  51         </varlistentry>
  52         <varlistentry>
  53             <term><parameter>shareList</parameter></term>
  54             <listitem>
  55                 <para>
  56                     Specifies the context with which to share display lists.
  57                     <constant>NULL</constant> indicates that no sharing is to take place.
  58                 </para>
  59             </listitem>
  60         </varlistentry>
  61         <varlistentry>
  62             <term><parameter>direct</parameter></term>
  63             <listitem>
  64                 <para>
  65                     Specifies whether rendering is to be done with a direct connection
  66                     to the graphics system if possible (<constant>True</constant>)
  67                     or through the X server (<constant>False</constant>).
  68                 </para>
  69             </listitem>
  70         </varlistentry>
  71         </variablelist>
  72     </refsect1>
  73     <refsect1 id="description"><title>Description</title>
  74         <para>
  75             <function>glXCreateContext</function> creates a GLX rendering context and returns its handle.
  76             This context can be used to render into both windows and GLX pixmaps.
  77             If <function>glXCreateContext</function> fails to create a rendering context,
  78             <constant>NULL</constant> is returned.
  79         </para>
  80         <para>
  81             If <parameter>direct</parameter> is <constant>True</constant>,
  82             then a direct rendering context is created if the
  83             implementation supports direct rendering, if the connection is to an X
  84             server that is local, and if a direct rendering context is available. (An implementation may return an indirect context when <parameter>direct</parameter> is <constant>True</constant>.)
  85             If <parameter>direct</parameter> is <constant>False</constant>,
  86             then a rendering context that renders through the X server is always created.
  87             Direct rendering provides a performance advantage in some implementations.
  88             However, direct rendering contexts cannot be shared outside a single process,
  89             and they may be unable to render to GLX pixmaps.
  90         </para>
  91         <para>
  92             If <parameter>shareList</parameter> is not <constant>NULL</constant>,
  93             then all display-list indexes and definitions are shared by
  94             context <parameter>shareList</parameter> and by the newly created context.
  95             An arbitrary number of contexts can share a single display-list space.
  96             However,
  97             all rendering contexts that share a single display-list space must
  98             themselves exist in the same address space.
  99             Two rendering contexts share an address space if both are nondirect
 100             using the same server,
 101             or if both are direct and owned by a single process.
 102             Note that in the nondirect case, it is not necessary for the calling
 103             threads to share an address space,
 104             only for their related rendering contexts to share an address space.
 105         </para>
 106         <para>
 107             If the GL version is 1.1 or greater,
 108             then all texture objects except object 0
 109             are shared by any contexts that share display lists.
 110         </para>
 111     </refsect1>
 112     <refsect1 id="notes"><title>Notes</title>
 113         <para>
 114             <constant>XVisualInfo</constant> is defined in <emphasis>Xutil.h.</emphasis>
 115             It is a structure that includes <emphasis>visual</emphasis>, <emphasis>visualID</emphasis>, <emphasis>screen</emphasis>, and
 116             <emphasis>depth</emphasis> elements.
 117         </para>
 118         <para>
 119             A <emphasis>process</emphasis> is a single execution environment,
 120             implemented in a single address space,
 121             consisting of one or more threads.
 122         </para>
 123         <para>
 124             A <emphasis>thread</emphasis> is one of a set of subprocesses that share
 125             a single address space,
 126             but maintain separate program counters,
 127             stack spaces,
 128             and other related global data.
 129             A <emphasis>thread</emphasis> that is the only member of its subprocess group
 130             is equivalent to a <emphasis>process</emphasis>.
 131         </para>
 132         <para>
 133             It may not be possible to render to a GLX pixmap with a direct rendering
 134             context.
 135         </para>
 136     </refsect1>
 137     <refsect1 id="errors"><title>Errors</title>
 138         <para>
 139             <constant>NULL</constant> is returned if execution fails on the client side.
 140         </para>
 141         <para>
 142             <constant>BadMatch</constant> is generated if the context to be created would not
 143             share the address space or the screen of the context specified by <parameter>shareList</parameter>.
 144         </para>
 145         <para>
 146             <constant>BadValue</constant> is generated if <parameter>vis</parameter> is not a valid visual (for
 147             example, if a particular GLX implementation does not support it).
 148         </para>
 149         <para>
 150             <constant>GLXBadContext</constant> is generated if <parameter>shareList</parameter> is not a GLX context
 151             and is not <constant>NULL</constant>.
 152         </para>
 153         <para>
 154             <constant>BadAlloc</constant> is generated if the server does not have enough
 155             resources to allocate the new context.
 156         </para>
 157     </refsect1>
 158     <refsect1 id="seealso"><title>See Also</title>
 159         <para>
 160             <citerefentry><refentrytitle>glXDestroyContext</refentrytitle></citerefentry>,
 161             <citerefentry><refentrytitle>glXGetConfig</refentrytitle></citerefentry>,
 162             <citerefentry><refentrytitle>glXIsDirect</refentrytitle></citerefentry>,
 163             <citerefentry><refentrytitle>glXMakeCurrent</refentrytitle></citerefentry>
 164         </para>
 165     </refsect1>
 166     <refsect1 id="Copyright"><title>Copyright</title>
 167         <para>
 168             Copyright <trademark class="copyright"></trademark> 1991-2006
 169             Silicon Graphics, Inc. This document is licensed under the SGI
 170             Free Software B License. For details, see
 171             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 172         </para>
 173     </refsect1>
 174 </refentry>