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 xml:base="" id="eglCreateContext"> 5 <refentryinfo> 6 <copyright> 7 <year>2003-2014</year> 8 <holder>The Khronos Group Inc.</holder> 9 </copyright> 10 </refentryinfo> 11 <refmeta> 12 <refentrytitle>eglCreateContext</refentrytitle> 13 <manvolnum>3G</manvolnum> 14 </refmeta> 15 <refnamediv> 16 <refname>eglCreateContext</refname> 17 <refpurpose> 18 create a new <acronym>EGL</acronym> rendering context 19 </refpurpose> 20 </refnamediv> 21 <refsynopsisdiv> 22 <title>C Specification</title> 23 <funcsynopsis> 24 <funcprototype> 25 <funcdef>EGLContext <function>eglCreateContext</function></funcdef> 26 <paramdef>EGLDisplay <parameter>display</parameter></paramdef> 27 <paramdef>EGLConfig <parameter>config</parameter></paramdef> 28 <paramdef>EGLContext <parameter>share_context</parameter></paramdef> 29 <paramdef>EGLint const * <parameter>attrib_list</parameter></paramdef> 30 </funcprototype> 31 </funcsynopsis> 32 </refsynopsisdiv> 33 <refsect1 id="parameters"><title>Parameters</title> 34 <variablelist> 35 <varlistentry> 36 <term><parameter>display</parameter></term> 37 <listitem><para> 38 Specifies the 39 <acronym>EGL</acronym> 40 display connection. 41 </para></listitem> 42 </varlistentry> 43 <varlistentry> 44 <term><parameter>config</parameter></term> 45 <listitem><para>Specifies the EGL frame buffer configuration that 46 defines the frame buffer resource available to the rendering context. 47 </para></listitem> 48 </varlistentry> 49 <varlistentry> 50 <term><parameter>share_context</parameter></term> 51 <listitem><para> 52 Specifies another 53 <acronym>EGL</acronym> 54 rendering context with which to share data, as 55 defined by the client API corresponding to the 56 contexts. Data is also shared with all other 57 contexts with which 58 <parameter>share_context</parameter> shares data. 59 <constant>EGL_NO_CONTEXT</constant> indicates that 60 no sharing is to take place. 61 </para> 62 </listitem> 63 </varlistentry> 64 <varlistentry> 65 <term><parameter>attrib_list</parameter></term> 66 <listitem><para> 67 Specifies attributes and attribute values for the 68 context being created. Only the attribute 69 <constant>EGL_CONTEXT_CLIENT_VERSION</constant> may 70 be specified. 71 </para></listitem> 72 </varlistentry> 73 </variablelist> 74 </refsect1> 75 <refsect1 id="description"><title>Description</title> 76 <para> 77 <function>eglCreateContext</function> creates an EGL 78 rendering context for the current rendering API (as set with 79 <function>eglBindAPI</function>) and returns a handle to the 80 context. The context can then be used to render into an EGL 81 drawing surface. If <function>eglCreateContext</function> 82 fails to create a rendering context, 83 <constant>EGL_NO_CONTEXT</constant> is returned. 84 </para> 85 <para> 86 If <parameter>share_context</parameter> is not 87 <constant>EGL_NO_CONTEXT</constant>, then all shareable data 88 in the context (as defined by the client API specification 89 for the current rendering API) are shared by context 90 <parameter>share_context</parameter>, all other contexts 91 <parameter>share_context</parameter> already shares with, 92 and the newly created context. An arbitrary number of 93 rendering contexts can share data. However, all rendering 94 contexts that share data must themselves exist in the same 95 address space. Two rendering contexts share an address space 96 if both are owned by a single process. 97 </para> 98 <para> 99 <parameter>attrib_list</parameter> specifies a list of 100 attributes for the context. The list has the same structure 101 as described for <function>eglChooseConfig</function>. The 102 attributes and attribute values which may be specified are 103 as follows: 104 </para> 105 <variablelist> 106 <varlistentry> 107 <term><constant>EGL_CONTEXT_CLIENT_VERSION</constant></term> 108 <listitem><para> 109 Must be followed by an integer that determines which 110 version of an OpenGL ES context to create. A value 111 of 1 specifies creation of an OpenGL ES 1.x context. 112 An attribute value of 2 specifies creation of an 113 OpenGL ES 2.x context. The default value is 1. This 114 attribute can only be specified when creating a 115 OpenGL ES context (e.g. when the current rendering 116 API is <constant>EGL_OPENGL_ES_API</constant>). 117 </para></listitem> 118 </varlistentry> 119 </variablelist> 120 </refsect1> 121 <refsect1 id="notes"><title>Notes</title> 122 <para> 123 The current rendering API is only respected if the EGL 124 version is 1.2 or greater. Otherwise, an OpenGL ES context 125 will always be created. 126 </para> 127 <para> 128 The <constant>EGL_CONTEXT_CLIENT_VERSION</constant> 129 attribute is only supported if the EGL version is 1.3 or 130 greater. 131 </para> 132 <para> 133 A <firstterm>process</firstterm> is a single execution environment, 134 implemented in a single address space, consisting of one or more threads. 135 </para> 136 <para> 137 A <firstterm>thread</firstterm> is one of a set of subprocesses that 138 share a single address space, but maintain separate program counters, 139 stack spaces, and other related global data. 140 A thread is the only member of its subprocess group is equivalent to a 141 process. 142 </para> 143 </refsect1> 144 <refsect1 id="errors"><title>Errors</title> 145 <para> 146 <constant>EGL_NO_CONTEXT</constant> is returned if creation of 147 the context fails. 148 </para> 149 <para> 150 <constant>EGL_BAD_MATCH</constant> is generated if the 151 current rendering API is <constant>EGL_NONE</constant> (this 152 can only arise in an EGL implementation which does not 153 support OpenGL ES, prior to the first call to 154 <function>eglBindAPI</function>). 155 </para> 156 <para> 157 <constant>EGL_BAD_MATCH</constant> is generated if the 158 server context state for 159 <parameter>share_context</parameter> exists in an address 160 space which cannot be shared with the newly created context, 161 if <parameter>share_context</parameter> was created on a 162 different display than the one referenced by 163 <parameter>config</parameter>, or if the contexts are 164 otherwise incompatible. 165 </para> 166 <para> 167 <constant>EGL_BAD_DISPLAY</constant> is generated if 168 <parameter>display</parameter> is not an EGL display connection. 169 </para> 170 <para> 171 <constant>EGL_NOT_INITIALIZED</constant> is generated if 172 <parameter>display</parameter> has not been initialized. 173 </para> 174 <para> 175 <constant>EGL_BAD_CONFIG</constant> is generated if 176 <parameter>config</parameter> is not an EGL frame buffer 177 configuration, or does not support the current rendering 178 API. This includes requesting creation of an OpenGL ES 1.x 179 context when the <constant>EGL_RENDERABLE_TYPE</constant> 180 attribute of <parameter>config</parameter> does not contain 181 <constant>EGL_OPENGL_ES_BIT</constant>, or creation of an 182 OpenGL ES 2.x context when the attribute does not contain 183 <constant>EGL_OPENGL_ES2_BIT</constant>. 184 </para> 185 <para> 186 <constant>EGL_BAD_CONTEXT</constant> is generated if 187 <parameter>share_context</parameter> is not an EGL rendering 188 context of the same client API type as the newly created 189 context and is not <constant>EGL_NO_CONTEXT</constant>. 190 </para> 191 <para> 192 <constant>EGL_BAD_ATTRIBUTE</constant> is generated if 193 <parameter>attrib_list</parameter> contains an invalid 194 context attribute or if an attribute is not recognized or 195 out of range. Note that attribute 196 <constant>EGL_CONTEXT_CLIENT_VERSION</constant> is 197 only valid when the current rendering API is 198 <constant>EGL_OPENGL_ES_API</constant>. 199 </para> 200 <para> 201 <constant>EGL_BAD_ALLOC</constant> is generated if there are not 202 enough resources to allocate the new context. 203 </para> 204 </refsect1> 205 <refsect1 id="seealso"><title>See Also</title> 206 <para> 207 <citerefentry><refentrytitle>eglDestroyContext</refentrytitle></citerefentry>, 208 <citerefentry><refentrytitle>eglChooseConfig</refentrytitle></citerefentry>, 209 <citerefentry><refentrytitle>eglGetConfigs</refentrytitle></citerefentry>, 210 <citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry> 211 </para> 212 </refsect1> 213 <refsect3 id="Copyright"><title></title> 214 <!-- Content included from copyright.inc.xsl --> 215 <imageobject> 216 <imagedata fileref="KhronosLogo.jpg" format="jpg" /> 217 </imageobject> 218 <para /> 219 </refsect3> 220</refentry> 221
