What is the status of EGL_MESA_screen_surface?
Paul.Ramsey at Sun.COM
Thu Feb 23 16:32:08 PST 2006
I'm new to DRI EGL but I'm definitely not new to API design.
What is the status of EGL_MESA_screen_surface? Has this been discussed at
Khronos as an extension to EGL?
I've read through the entire archive of this list going back to last March and
one fundamental thing I can't find is how EGL went from being an API for
implementing OpenGL on a graphics device to being an API for being able to
implement a window system on the device.
While I might disagree with some of the details, fundamentally all of the
capabilities in EGL_MESA_screen_surface are important capabilities for building
a window system, but I don't see why this is an EGL extension rather than part
of a the native environment under which EGL runs. Being the native environment,
EGL would have some knowledge of operations which happened in this screen/video
mode control library but that doesn't require that it be in the form of an
extension to EGL.
I would propose that
1. These functions should be changed to not use the EGL or egl prefix
2. eglCreateScreenSurface (or it's renamed equivalent) should return a handle
to a displayable frame buffer objects but that it isn't a "Surface". I'll
call it PREFIXDisplaybuffer for the moment.
3. A native way needs to be created for referring to a device, this would get
passed into these functions rather than EGLDisplay. This would also
get passed into eglGetDisplay() to get a corresponding EGLDisplay. The
most trivial change to the existing implementation, PREFIXDevice would
really be the same as EGLDisplay, just typed different for the interface
4. eglCreateWindowSurface() would accept these PREFIXDisplaybuffer objects
to introduce them into EGL to make them into a window as an EGLSurface
Otherwise the functions could stay as they are. This isn't really a major change
to the interface as it's defined, just getting it out of EGL where it doesn't
If everyone wants to send the mail telling me why I'm an idiot directly to me,
I'll summarize to the list. :-)
Sun Microsystems, Inc.
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