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Name
MESA_platform_surfaceless
Name Strings
EGL_MESA_platform_surfaceless
Contributors
Chad Versace <chadversary@google.com>
Haixia Shi <hshi@google.com>
Stéphane Marchesin <marcheu@google.com>
Zach Reizner <zachr@chromium.org>
Gurchetan Singh <gurchetansingh@google.com>
Contacts
Chad Versace <chadversary@google.com>
Status
DRAFT
Version
Version 2, 2016-10-13
Number
EGL Extension #TODO
Extension Type
EGL client extension
Dependencies
Requires EGL 1.5 or later; or EGL 1.4 with EGL_EXT_platform_base.
This extension is written against the EGL 1.5 Specification (draft
20140122).
This extension interacts with EGL_EXT_platform_base as follows. If the
implementation supports EGL_EXT_platform_base, then text regarding
eglGetPlatformDisplay applies also to eglGetPlatformDisplayEXT;
eglCreatePlatformWindowSurface to eglCreatePlatformWindowSurfaceEXT; and
eglCreatePlatformPixmapSurface to eglCreatePlatformPixmapSurfaceEXT.
Overview
This extension defines a new EGL platform, the "surfaceless" platform. This
platfom's defining property is that it has no native surfaces, and hence
neither eglCreatePlatformWindowSurface nor eglCreatePlatformPixmapSurface
can be used. The platform is independent of any native window system.
The platform's intended use case is for enabling OpenGL and OpenGL ES
applications on systems where no window system exists. However, the
platform's permitted usage is not restricted to this case. Since the
platform is independent of any native window system, it may also be used on
systems where a window system is present.
New Types
None
New Procedures and Functions
None
New Tokens
Accepted as the <platform> argument of eglGetPlatformDisplay:
EGL_PLATFORM_SURFACELESS_MESA 0x31DD
Additions to the EGL Specification
None.
New Behavior
To determine if the EGL implementation supports this extension, clients
should query the EGL_EXTENSIONS string of EGL_NO_DISPLAY.
To obtain an EGLDisplay on the surfaceless platform, call
eglGetPlatformDisplay with <platform> set to EGL_PLATFORM_SURFACELESS_MESA.
The <native_display> parameter must be EGL_DEFAULT_DISPLAY.
eglCreatePlatformWindowSurface fails when called with a <display> that
belongs to the surfaceless platform. It returns EGL_NO_SURFACE and
generates EGL_BAD_NATIVE_WINDOW. The justification for this unconditional
failure is that the surfaceless platform has no native windows, and
therefore the <native_window> parameter is always invalid.
Likewise, eglCreatePlatformPixmapSurface also fails when called with a
<display> that belongs to the surfaceless platform. It returns
EGL_NO_SURFACE and generates EGL_BAD_NATIVE_PIXMAP.
The surfaceless platform imposes no platform-specific restrictions on the
creation of pbuffers, as eglCreatePbufferSurface has no native surface
parameter. Specifically, if the EGLDisplay advertises an EGLConfig whose
EGL_SURFACE_TYPE attribute contains EGL_PBUFFER_BIT, then the EGLDisplay
permits the creation of pbuffers with that config.
Issues
None.
Revision History
Version 2, 2016-10-13 (Chad Versace)
- Assign enum values
- Define interfactions with EGL 1.4 and EGL_EXT_platform_base.
- Add Gurchetan as contributor, as he implemented the pbuffer support.
Version 1, 2016-09-23 (Chad Versace)
- Initial version
- Posted for review at
https://lists.freedesktop.org/archives/mesa-dev/2016-September/129549.html
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