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Name
ANGLE_external_context_and_surface
Name Strings
EGL_ANGLE_external_context_and_surface
Contributors
Peng Huang
Shahbaz Youssefi
Contacts
Shahbaz Youssefi, Google (syoussefi 'at' google.com)
Status
Draft
Version
Version 2, July 24, 2023
Number
EGL Extension #??
Dependencies
This extension is written against the wording of the EGL 1.4
Specification.
Overview
This extension allows plugging an external OpenGL context and surface to
the OpenGL backend of ANGLE.
New Types
None
New Procedures and Functions
void eglAcquireExternalContextANGLE(
EGLDisplay dpy);
void eglReleaseExternalContextANGLE(
EGLDisplay dpy);
New Tokens
Accepted as an attribute name in the <*attrib_list> argument to
eglCreateContext:
EGL_EXTERNAL_CONTEXT_ANGLE 0x348E
EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE 0x3490
Accepted in the <buftype> parameter of eglCreatePbufferFromClientBuffer:
EGL_EXTERNAL_SURFACE_ANGLE 0x348F
Additions to the EGL 1.4 Specification
Add the following to section 3.7.1 "Creating Rendering Contexts":
EGL_EXTERNAL_CONTEXT_ANGLE indicates whether the context is externally
managed, and that no internal context is created.
In this case, the context must be made current by the application before
calling other EGL or GL functions that may access the context.
EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE indicates whether the context state
is automatically synchronized from and to the external context when
eglMakeCurrent is called.
eglAcquireExternalContextANGLE and eglReleaseExternalContextANGLE can be
used to perform this synchronization independently from MakeCurrent.
Add the following to section 3.5.3 "Binding Off-Screen Rendering Surfaces
To Client Buffers":
EGL_EXTERNAL_SURFACE_ANGLE indicates whether the surface is externally
managed, and that no internal surface is created.
In this case, the surface must be made current by the application before
calling other EGL or GL functions that may access the surface.
Add the following to section 3.7.3 "Binding Contexts and Drawables":
Before making a call that uses a context created with
EGL_EXTERNAL_CONTEXT_ANGLE, the context must be synchronized from external.
If EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE is specified when creating the
context, this can be done with a call to eglMakeCurrent.
Alternatively, eglAcquireExternalContextANGLE can be called to perform this
synchronization.
The eglAcquireExternalContextANGLE call ensures that the implementation is
up-to-date with respect to changes that external has made to the context.
Before the application (external) can continue using the context after the
implementation has modified it, the context must be synchronized to
external, restoring the state from when the external context was
"acquired".
If EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE is specified when creating the
context, this can be done with a call to eglMakeCurrent that sets the
context to NULL.
Alternatively, eglReleaseExternalContextANGLE can be called to perform this
synchronization.
The eglReleaseExternalContextANGLE call ensures that the context is
restored to its original state from before the
eglAcquireExternalContextANGLE call.
Issues
None yet.
Revision History
Rev. Date Author Changes
---- ------------- --------- ----------------------------------------
1 Jan 7, 2021 penghuang Initial version
2 July 24, 2023 syoussefi Add eglAcquireExternalContextANGLE, and
eglReleaseExternalContextANGLE