| 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="glXMakeCurrent"> |
| 5 | <refmeta> |
| 6 | <refmetainfo> |
| 7 | <copyright> |
| 8 | <year>1991-2006</year> |
| 9 | <holder>Silicon Graphics, Inc.</holder> |
| 10 | </copyright> |
| 11 | </refmetainfo> |
| 12 | <refentrytitle>glXMakeCurrent</refentrytitle> |
| 13 | <manvolnum>3G</manvolnum> |
| 14 | </refmeta> |
| 15 | <refnamediv> |
| 16 | <refname>glXMakeCurrent</refname> |
| 17 | <refpurpose>attach a GLX context to a window or a GLX pixmap</refpurpose> |
| 18 | </refnamediv> |
| 19 | <refsynopsisdiv><title>C Specification</title> |
| 20 | <funcsynopsis> |
| 21 | <funcprototype> |
| 22 | <funcdef>Bool <function>glXMakeCurrent</function></funcdef> |
| 23 | <paramdef>Display * <parameter>dpy</parameter></paramdef> |
| 24 | <paramdef>GLXDrawable <parameter>drawable</parameter></paramdef> |
| 25 | <paramdef>GLXContext <parameter>ctx</parameter></paramdef> |
| 26 | </funcprototype> |
| 27 | </funcsynopsis> |
| 28 | </refsynopsisdiv> |
| 29 | <!-- eqn: ignoring delim $$ --> |
| 30 | <refsect1 id="parameters"><title>Parameters</title> |
| 31 | <variablelist> |
| 32 | <varlistentry> |
| 33 | <term><parameter>dpy</parameter></term> |
| 34 | <listitem> |
| 35 | <para> |
| 36 | Specifies the connection to the X server. |
| 37 | </para> |
| 38 | </listitem> |
| 39 | </varlistentry> |
| 40 | <varlistentry> |
| 41 | <term><parameter>drawable</parameter></term> |
| 42 | <listitem> |
| 43 | <para> |
| 44 | Specifies a GLX drawable. |
| 45 | Must be either an X window ID or a GLX pixmap ID. |
| 46 | </para> |
| 47 | </listitem> |
| 48 | </varlistentry> |
| 49 | <varlistentry> |
| 50 | <term><parameter>ctx</parameter></term> |
| 51 | <listitem> |
| 52 | <para> |
| 53 | Specifies a GLX rendering context that is to be attached to <parameter>drawable</parameter>. |
| 54 | </para> |
| 55 | </listitem> |
| 56 | </varlistentry> |
| 57 | </variablelist> |
| 58 | </refsect1> |
| 59 | <refsect1 id="description"><title>Description</title> |
| 60 | <para> |
| 61 | <function>glXMakeCurrent</function> does two things: |
| 62 | It makes <parameter>ctx</parameter> the current GLX rendering context of the calling thread, |
| 63 | replacing the previously current context if there was one, |
| 64 | and it attaches <parameter>ctx</parameter> to a GLX drawable, |
| 65 | either a window or a GLX pixmap. |
| 66 | As a result of these two actions, |
| 67 | subsequent GL rendering calls |
| 68 | use rendering context <parameter>ctx</parameter> to modify GLX drawable <parameter>drawable</parameter> (for |
| 69 | reading and writing). |
| 70 | Because <function>glXMakeCurrent</function> always replaces the current rendering context with <parameter>ctx</parameter>, |
| 71 | there can be only one current context per thread. |
| 72 | </para> |
| 73 | <para> |
| 74 | Pending commands to the |
| 75 | previous context, if any, are flushed before it is released. |
| 76 | </para> |
| 77 | <para> |
| 78 | The first time <parameter>ctx</parameter> is made current to any thread, |
| 79 | its viewport is set to the full size of <parameter>drawable</parameter>. |
| 80 | Subsequent calls by any thread to <function>glXMakeCurrent</function> with <parameter>ctx</parameter> |
| 81 | have no effect on its viewport. |
| 82 | </para> |
| 83 | <para> |
| 84 | To release the current context without assigning a new one, |
| 85 | call <function>glXMakeCurrent</function> with <parameter>drawable</parameter> set to <constant>None</constant> and <parameter>ctx</parameter> |
| 86 | set to <constant>NULL</constant>. |
| 87 | </para> |
| 88 | <para> |
| 89 | <function>glXMakeCurrent</function> returns <constant>True</constant> if it is successful, |
| 90 | <constant>False</constant> otherwise. |
| 91 | If <constant>False</constant> is returned, the previously current rendering context |
| 92 | and drawable (if any) remain unchanged. |
| 93 | </para> |
| 94 | </refsect1> |
| 95 | <refsect1 id="notes"><title>Notes</title> |
| 96 | <para> |
| 97 | A <emphasis>process</emphasis> is a single-execution environment, |
| 98 | implemented in a single address space, |
| 99 | consisting of one or more threads. |
| 100 | </para> |
| 101 | <para> |
| 102 | A <emphasis>thread</emphasis> is one of a set of subprocesses that share |
| 103 | a single address space, |
| 104 | but maintain separate program counters, |
| 105 | stack spaces, |
| 106 | and other related global data. |
| 107 | A <emphasis>thread</emphasis> that is the only member of its subprocess group |
| 108 | is equivalent to a <emphasis>process</emphasis>. |
| 109 | </para> |
| 110 | </refsect1> |
| 111 | <refsect1 id="errors"><title>Errors</title> |
| 112 | <para> |
| 113 | <constant>BadMatch</constant> is generated if <parameter>drawable</parameter> was not |
| 114 | created with the same X screen and visual as <parameter>ctx</parameter>. |
| 115 | It is also generated if <parameter>drawable</parameter> is <constant>None</constant> and <parameter>ctx</parameter> is not |
| 116 | <constant>NULL</constant>. |
| 117 | </para> |
| 118 | <para> |
| 119 | <constant>BadAccess</constant> is generated if <parameter>ctx</parameter> was current to another thread |
| 120 | at the time <function>glXMakeCurrent</function> was called. |
| 121 | </para> |
| 122 | <para> |
| 123 | <constant>GLXBadDrawable</constant> is generated if <parameter>drawable</parameter> is not a valid GLX drawable. |
| 124 | </para> |
| 125 | <para> |
| 126 | <constant>GLXBadContext</constant> is generated if <parameter>ctx</parameter> is not a valid GLX context. |
| 127 | </para> |
| 128 | <para> |
| 129 | <constant>GLXBadContextState</constant> is generated if <function>glXMakeCurrent</function> is executed between |
| 130 | the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. |
| 131 | </para> |
| 132 | <para> |
| 133 | <constant>GLXBadContextState</constant> is also generated if the rendering context current |
| 134 | to the calling thread has GL renderer state <constant>GLX_FEEDBACK</constant> or |
| 135 | <constant>GLX_SELECT</constant>. |
| 136 | </para> |
| 137 | <para> |
| 138 | <constant>GLXBadCurrentWindow</constant> is generated if there are pending GL |
| 139 | commands for the previous context and the current drawable is |
| 140 | a window that is no longer valid. |
| 141 | </para> |
| 142 | <para> |
| 143 | <constant>BadAlloc</constant> may be generated if the server has delayed allocation |
| 144 | of ancillary buffers until <function>glXMakeCurrent</function> is called, only to find that it has |
| 145 | insufficient resources to complete the allocation. |
| 146 | </para> |
| 147 | </refsect1> |
| 148 | <refsect1 id="seealso"><title>See Also</title> |
| 149 | <para> |
| 150 | <citerefentry><refentrytitle>glXCreateContext</refentrytitle></citerefentry>, |
| 151 | <citerefentry><refentrytitle>glXCreateGLXPixmap</refentrytitle></citerefentry> |
| 152 | <citerefentry><refentrytitle>glXGetCurrentContext</refentrytitle></citerefentry>, |
| 153 | <citerefentry><refentrytitle>glXGetCurrentDisplay</refentrytitle></citerefentry>, |
| 154 | <citerefentry><refentrytitle>glXGetCurrentDrawable</refentrytitle></citerefentry>, |
| 155 | <citerefentry><refentrytitle>glXGetCurrentReadDrawable</refentrytitle></citerefentry>, |
| 156 | <citerefentry><refentrytitle>glXMakeContextCurrent</refentrytitle></citerefentry> |
| 157 | </para> |
| 158 | </refsect1> |
| 159 | <refsect1 id="Copyright"><title>Copyright</title> |
| 160 | <para> |
| 161 | Copyright <trademark class="copyright"></trademark> 1991-2006 |
| 162 | Silicon Graphics, Inc. This document is licensed under the SGI |
| 163 | Free Software B License. For details, see |
| 164 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. |
| 165 | </para> |
| 166 | </refsect1> |
| 167 | </refentry> |