EGL_MESA_screen_surface version 5
Jim.Gettys at hp.com
Fri Apr 22 09:30:21 PDT 2005
FWIW: we need to move to a model where everything is dynamic, including
screens, given modern hotplug hardware and software systems.
So try to keep that in mind, while doing the API design...
On Fri, 2005-04-22 at 12:19 -0400, Adam Jackson wrote:
> On Wednesday 06 April 2005 18:12, Brian Paul wrote:
> I've been implementing this in my IndieGL toy and I've found a few issues.
> eglScreenPositionMESA() is listed in the Additions section but not in the New
> Procedures and Functions section.
> > EGLBoolean eglQueryDisplayMESA(EGLDisplay dpy, EGLint screen_number,
> > EGLint attrib, EGLint *value)
> > Used to query display parameters. <attrib> may be one of the following:
> > Name Return value description
> > ------------------ ---------------------------------------------
> > EGL_NUM_SCREENS Number of screens associated with the display
> In the new tokens section this was called EGL_SCREEN_COUNT_MESA.
> I don't see any semantic value in passing a screen_number to QueryDisplay, are
> we just leaving that in for future expansion?
> There's a minor issue here, in that it's not clear whether
> EGL_SCREEN_COUNT_MESA is the number of active screens or the number of
> possible screens. This is more of an issue for me trying to do a GLX wrapper
> than it probably is for real hardware, for now anyway, but who knows how
> hotpluggable things will be in the future.
> I suggest the following clarification. EGL_SCREEN_COUNT_MESA is the maximum
> number of screens on the device, where zero indicates that the device is
> hotpluggable. EGLint screen_number parameters are valid in the range 0 to
> EGL_SCREEN_COUNT_MESA-1 when ESCM is >0. When ESCM == 0, you may check the
> validity of a particular screen_number by calling QueryScreenSurface on it.
> EGL_FALSE/EGL_BAD_SCREEN_MESA indicates an invalid screen number; EGL_TRUE
> indicates a valid screen number with possibly no screen surface currently
> being displayed.
> When doing EGL-GLX translation you can create arbitrary numbers of screens,
> because they're just windows, so CreateScreenSurface can just fail or succeed
> based on whether XCreateWindow works. That should work for more distributed
> setups too, but there might need to be a new entrypoint to hand the
> application an opaque screen_number to use. Not something I think we need to
> design now though.
> - ajax
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