extensions/EGL_ANGLE_external_context_and_surface.txt

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

    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.

    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.
    eglAcquireExternalContextANGLE can be called to perform this
    synchronization, ensuring 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".
    eglReleaseExternalContextANGLE can be called to perform this
    synchronization, ensuring 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
      3   July 27, 2023  syoussefi  Remove EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE