blob: ca911d14a2bee8aacef20c5f25c13296a1af1623 [file] [log] [blame]
Name Strings
NOTE: implementations of this extension must export BOTH extension
strings, for backwards compatibility with applications written
against version 1 of this extension.
Jon Leech (jon 'at'
Piers Daniell (pdaniell 'at'
IP Status
No known IP claims.
Version 5, April 6, 2012
WGL_ARB_extensions_string is required.
WGL_ARB_create_context is required.
WGL_ARB_create_context_profile is required.
An OpenGL ES implementation is required.
This extension allows creating an OpenGL ES context.
New Procedures and Functions
New Tokens
Accepted as a bit in the attribute value for
Additions to the OpenGL / GLX / GLX Protocol Specificaitons
None. This specification is written for WGL.
Additions to the WGL specification
This extension modifies language specified in the
WGL_ARB_create_context and WGL_ARB_create_context_profile
In the description of wglCreateContextAttribsARB, replace the
"... If a version less than or equal to 3.0 is requested, the context
returned may implement any of the following versions:"
"... If the version requested is a valid and supported OpenGL-ES version,
and the WGL_CONTEXT_ES_PROFILE_BIT_EXT bit is set in the
WGL_CONTEXT_PROFILE_MASK_ARB attribute (see below), then the context
returned will implement the OpenGL ES version requested.
Otherwise, if a version less than or equal to 3.0 is requested, the
context returned may implement any of the following versions:"
Replace the sentence
"... If the requested OpenGL version is less than 3.2,
WGL_CONTEXT_PROFILE_MASK_ARB is ignored and the functionality of the
context is determined solely by the requested version."
"... If the WGL_CONTEXT_ES_PROFILE_BIT_EXT bit is set, and the
requested version is a valid and supported OpenGL-ES implementation,
then a context implementing that OpenGL ES version is returned;
otherwise, if the requested OpenGL version is less than
3.2, WGL_CONTEXT_PROFILE_MASK_ARB is ignored and the functionality
of the context is determined solely by the requested version."
Add prior to the sentence
"The attribute name WGL_CONTEXT_FLAGS_ARB specifies a set of flag
bits affecting the rendering context.":
"If an OpenGL ES profile is requested, then the context returned
cannot implement additional functionality, including functionality
defined only by the core or compatibility profiles, unless such
functionality is defined by extensions that are themselves specified
relative to that specific OpenGL ES version[*].
[*] Such functionality should have a corresponding extension
specification in the OpenGL ES Registry. In some
implementations, vendor extensions defined relative to the OpenGL ES
version, but not yet added to the OpenGL ES Registry, may also be
Replace the bullet point starting "* If attribute
WGL_CONTEXT_PROFILE_MASK_ARB has no bits set;..." with
"* If attribute WGL_CONTEXT_PROFILE_MASK_ARB has no bits set; has any
WGL_CONTEXT_ES_PROFILE_BIT_EXT; has more than one of these bits
set; or if the implementation does not supported the requested
profile, then ERROR_INVALID_PROFILE_ARB is generated."
Dependencies on WGL_ARB_extensions_string
Because there is no way to extend WGL, these calls are defined in
the ICD and can be called by obtaining the address with
wglGetProcAddress. Because this extension is a WGL extension, it is
not included in the GL_EXTENSIONS string. Its existence can be
determined with the WGL_ARB_extensions_string extension.
ERROR_INVALID_PROFILE_ARB is generated if the value of
WGL_CONTEXT_PROFILE_MASK_ARB contains more than a single valid
profile bit.
New State
New Implementation Dependent State
Conformance Tests
Sample Code
1) How is an OpenGL ES 2.0 "profile" defined in a desktop OpenGL
OpenGL ES 2.0 is essentially a stripped-down version of OpenGL 2.0
with a few added features, so it is natural to consider it a profile
of OpenGL 2.0. This is potentially confusing, in that the API
profile mechanism was not introduced until OpenGL 3.2. However, the
extended context creation mechanism operates outside the scope of a
GL context, and we can define the meaning of "version 2.0, profile
ES2" to be an OpenGL ES 2.0 context.
2) May an OpenGL ES 2.0 "profile" include OpenGL functionality
introduced by OpenGL 2.1 and later versions?
PROPOSED: NO, except in the form of extensions that are themselves
defined relative to OpenGL ES 2.0. This restriction is intended to
make it difficult to create ill-defined conglomerations of OpenGL ES
and OpenGL features and to eliminate subjective interpretations of
what it means to subset a GL extension for implementation against
OpenGL ES.
If features specific to OpenGL ES 2.0 are required together with
features from recent versions of OpenGL, a different mechanism, such
as an OpenGL extension defining those OpenGL ES 2.0 features, may be
3) Is implementation of an OpenGL ES 2.0 profile mandatory for a
desktop OpenGL implementation?
RESOLVED: NO. The ARB considered making support for an ES 2.0
profile mandatory for an OpenGL 4.1 implementation, but decided
against it. Most ARB members would prefer that people use EGL to
access OpenGL ES 2.0, whether on the desktop or on mobile devices.
4) Do we need a GL_CONTEXT_ES2_PROFILE_BIT_EXT token?
RESOLVED: NO. The GL_CONTEXT_PROFILE_MASK query only exists in
desktop GL, while creating an ES2 "profile" results in an OpenGL ES
2.0 context, which does not have the query. Therefore at present,
it's not possible to ever return this bit from the query and it is
not needed.
If, in the future, ES and GL are unified under the profile mechanism
such that there is an actual "embedded" profile of GL, then this
resolution may need to change.
5) Do we need a new extension and new profile bit for every different
version of OpenGL-ES the desktop OpenGL implementation wants to
RESOLVED: No. This extension has been modified since version #3 to
support and requested version of OpenGL-ES that is supported by
the desktop OpenGL implementation. This can include more than just
OpenGL-ES 2.0 that was originally specified.
The name string has been generalized from "es2_profile" to
"es_profile" for future use, but for backwards compatibility with
applications expecting the initial name string, implementations are
required to export both name strings.
Revision History
Version 5, 2012/04/06 - Specify that both name strings must be
exported for backwards compatibility and expand issue 5
Version 4, 2012/03/28 - Add support for any OpenGL-ES version, not just
version 2.0. Alias WGL_CONTEXT_ES2_PROFILE_BIT_EXT with
WGL_CONTEXT_ES_PROFILE_BIT_EXT and the extension name
WGL_EXT_create_context_es2_profile with
WGL_EXT_create_context_es_profile. Added issue 5.
Version 3, 2010/08/09 - Added issue 4 resolution.
Version 2, 2010/08/04 - Fix typos and assign extension number.
Version 1, 2010/05/18 - Recast the OpenGL ES 2.0 "profile" mechanism
into a separate EXT layered on the ARB profiled context creation