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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglCreateContext">
<info>
<copyright>
<year>2003-2018</year>
<holder>The Khronos Group Inc.</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>eglCreateContext</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>eglCreateContext</refname>
<refpurpose>
create a new <acronym>EGL</acronym> rendering context
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>EGLContext <function>eglCreateContext</function></funcdef>
<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
<paramdef>EGLConfig <parameter>config</parameter></paramdef>
<paramdef>EGLContext <parameter>share_context</parameter></paramdef>
<paramdef>EGLint const * <parameter>attrib_list</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>display</parameter></term>
<listitem><para>
Specifies the
<acronym>EGL</acronym>
display connection.
</para></listitem>
</varlistentry>
<varlistentry>
<term><parameter>config</parameter></term>
<listitem><para>Specifies the EGL frame buffer configuration that
defines the frame buffer resource available to the rendering context.
</para></listitem>
</varlistentry>
<varlistentry>
<term><parameter>share_context</parameter></term>
<listitem><para>
Specifies another
<acronym>EGL</acronym>
rendering context with which to share data, as
defined by the client API corresponding to the
contexts. Data is also shared with all other
contexts with which
<parameter>share_context</parameter> shares data.
<constant>EGL_NO_CONTEXT</constant> indicates that
no sharing is to take place.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>attrib_list</parameter></term>
<listitem><para>
Specifies attributes and attribute values for the
context being created. Only the attribute
<constant>EGL_CONTEXT_CLIENT_VERSION</constant> may
be specified.
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>eglCreateContext</function> creates an EGL
rendering context for the current rendering API (as set with
<function>eglBindAPI</function>) and returns a handle to the
context. The context can then be used to render into an EGL
drawing surface. If <function>eglCreateContext</function>
fails to create a rendering context,
<constant>EGL_NO_CONTEXT</constant> is returned.
</para>
<para>
If <parameter>share_context</parameter> is not
<constant>EGL_NO_CONTEXT</constant>, then all shareable data
in the context (as defined by the client API specification
for the current rendering API) are shared by context
<parameter>share_context</parameter>, all other contexts
<parameter>share_context</parameter> already shares with,
and the newly created context. An arbitrary number of
rendering contexts can share data. However, all rendering
contexts that share data must themselves exist in the same
address space. Two rendering contexts share an address space
if both are owned by a single process.
</para>
<para>
<parameter>attrib_list</parameter> specifies a list of
attributes for the context. The list has the same structure
as described for <function>eglChooseConfig</function>. The
attributes and attribute values which may be specified are
as follows:
</para>
<variablelist>
<varlistentry>
<term><constant>EGL_CONTEXT_MAJOR_VERSION</constant></term>
<listitem><para>
Must be followed by an integer specifying the requested
major version of an OpenGL or OpenGL ES context. The
default value is 1. This attribute is an alias of the
older <constant>EGL_CONTEXT_CLIENT_VERSION</constant>,
and the tokens may be used interchangeably.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_MINOR_VERSION</constant></term>
<listitem><para>
Must be followed by an integer specifying the requested
minor version of an OpenGL or OpenGL ES context. The
default value is 0.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_OPENGL_PROFILE_MASK</constant></term>
<listitem><para>
Must be followed by an integer bitmask specifying the
<firstterm>profile</firstterm> of an OpenGL context.
Bits which may be set include
<constant>EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT</constant>
for a core profile and
<constant>EGL_CONTEXT_OPENGL_COMPATIBILITY_PROFILE_BIT</constant>
for a compatibility profile. The default value is
<constant>EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT</constant>.
All OpenGL 3.2 and later implementations are required to
implement the core profile, but implementation of the
compatibility profile is optional.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_OPENGL_DEBUG</constant></term>
<listitem><para>
Must be followed by <constant>EGL_TRUE</constant>,
specifying that an OpenGL or OpenGL ES <firstterm>debug
context</firstterm> should be created, or
<constant>EGL_FALSE</constant>, if a non-debug context
should be created. The default value is
<constant>EGL_FALSE</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE</constant></term>
<listitem><para>
Must be followed by <constant>EGL_TRUE</constant>,
specifying that a
<firstterm>forward-compatible</firstterm> OpenGL context
should be created, or <constant>EGL_FALSE</constant>, if
a non-forward-compatible context should be created. The
default value is <constant>EGL_FALSE</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_OPENGL_ROBUST_ACCESS</constant></term>
<listitem><para>
Must be followed by <constant>EGL_TRUE</constant>,
specifying that an OpenGL or OpenGL ES context
supporting <firstterm>robust buffer access</firstterm>
should be created, or <constant>EGL_FALSE</constant>, if
a non-robust context should be created. The default
value is <constant>EGL_FALSE</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY</constant></term>
<listitem><para>
Must be followed by
<constant>EGL_LOSE_CONTEXT_ON_RESET</constant>,
specifying that an OpenGL or OpenGL ES context with
reset notification behavior
<constant>GL_LOSE_CONTEXT_ON_RESET_ARB</constant> should
be created, or
<constant>EGL_NO_RESET_NOTIFICATION</constant>,
specifying that an OpenGL or OpenGL ES context with
reset notification behavior
<constant>GL_NO_RESET_NOTIFICATION_ARB</constant> should
be created, as described by the
<constant>GL_ARB_robustness</constant> extension.
</para><para>
If the
<constant>EGL_CONTEXT_OPENGL_ROBUST_ACCESS</constant>
attribute is not set to <constant>EGL_TRUE</constant>,
context creation will not fail, but the resulting
context may not support robust buffer access, and
therefore may not support the requested reset
notification strategy The default value for
<constant>EGL_CONTEXT_OPENGL_RESET_NOTIFICATION_STRATEGY</constant>
is <constant>EGL_NO_RESET_NOTIFICATION</constant> .
</para></listitem>
</varlistentry>
</variablelist>
<para>
There are many possible interactions between requested OpenGL
and OpenGL ES context creation attributes, depending on the API
versions and extensions supported by the implementation. These
interactions are described in detail in the EGL 1.5
Specification, but are not listed here for compactness. The
requested attributes may not be able to be satisfied, but
context creation may still succeed. Applications should ensure
that the OpenGL or OpenGL ES contexts supports needed features
before using them, by determining the actual context version,
supported extensions, and supported context flags using runtime
queries.
</para>
</refsect1>
</refentry>
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