2003-2014
The Khronos Group Inc.
eglCreateContext
3G
eglCreateContext
create a new EGL rendering context
C Specification
EGLContext eglCreateContext
EGLDisplay display
EGLConfig config
EGLContext share_context
EGLint const * attrib_list
Parameters
display
Specifies the
EGL
display connection.
config
Specifies the EGL frame buffer configuration that
defines the frame buffer resource available to the rendering context.
share_context
Specifies another
EGL
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
share_context shares data.
EGL_NO_CONTEXT indicates that
no sharing is to take place.
attrib_list
Specifies attributes and attribute values for the
context being created. Only the attribute
EGL_CONTEXT_CLIENT_VERSION may
be specified.
Description
eglCreateContext creates an EGL
rendering context for the current rendering API (as set with
eglBindAPI) and returns a handle to the
context. The context can then be used to render into an EGL
drawing surface. If eglCreateContext
fails to create a rendering context,
EGL_NO_CONTEXT is returned.
If share_context is not
EGL_NO_CONTEXT, then all shareable data
in the context (as defined by the client API specification
for the current rendering API) are shared by context
share_context, all other contexts
share_context 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.
attrib_list specifies a list of
attributes for the context. The list has the same structure
as described for eglChooseConfig. The
attributes and attribute values which may be specified are
as follows:
EGL_CONTEXT_CLIENT_VERSION
Must be followed by an integer that determines which
version of an OpenGL ES context to create. A value
of 1 specifies creation of an OpenGL ES 1.x context.
An attribute value of 2 specifies creation of an
OpenGL ES 2.x context. The default value is 1. This
attribute can only be specified when creating a
OpenGL ES context (e.g. when the current rendering
API is EGL_OPENGL_ES_API).
Notes
The current rendering API is only respected if the EGL
version is 1.2 or greater. Otherwise, an OpenGL ES context
will always be created.
The EGL_CONTEXT_CLIENT_VERSION
attribute is only supported if the EGL version is 1.3 or
greater.
A process is a single execution environment,
implemented in a single address space, consisting of one or more threads.
A thread is one of a set of subprocesses that
share a single address space, but maintain separate program counters,
stack spaces, and other related global data.
A thread is the only member of its subprocess group is equivalent to a
process.
Errors
EGL_NO_CONTEXT is returned if creation of
the context fails.
EGL_BAD_MATCH is generated if the
current rendering API is EGL_NONE (this
can only arise in an EGL implementation which does not
support OpenGL ES, prior to the first call to
eglBindAPI).
EGL_BAD_MATCH is generated if the
server context state for
share_context exists in an address
space which cannot be shared with the newly created context,
if share_context was created on a
different display than the one referenced by
config, or if the contexts are
otherwise incompatible.
EGL_BAD_DISPLAY is generated if
display is not an EGL display connection.
EGL_NOT_INITIALIZED is generated if
display has not been initialized.
EGL_BAD_CONFIG is generated if
config is not an EGL frame buffer
configuration, or does not support the current rendering
API. This includes requesting creation of an OpenGL ES 1.x
context when the EGL_RENDERABLE_TYPE
attribute of config does not contain
EGL_OPENGL_ES_BIT, or creation of an
OpenGL ES 2.x context when the attribute does not contain
EGL_OPENGL_ES2_BIT.
EGL_BAD_CONTEXT is generated if
share_context is not an EGL rendering
context of the same client API type as the newly created
context and is not EGL_NO_CONTEXT.
EGL_BAD_ATTRIBUTE is generated if
attrib_list contains an invalid
context attribute or if an attribute is not recognized or
out of range. Note that attribute
EGL_CONTEXT_CLIENT_VERSION is
only valid when the current rendering API is
EGL_OPENGL_ES_API.
EGL_BAD_ALLOC is generated if there are not
enough resources to allocate the new context.
See Also
eglDestroyContext,
eglChooseConfig,
eglGetConfigs,
eglMakeCurrent