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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> |