<div dir="ltr">I see. Thank you for the info. What i am trying to do is have multiple contexts with its own EGLSurface but sharing the same "window" or wl_surface on wayland, where one thread renders a gl_triangle and the other rendering gears. This was a simple client to teach myself queues and IPC of wayland, ofcourse it doesnt reflect "real world" clients. So with this setup i was wondering if a resize on the wl_egl_window will seamlessly take effect on both EGLSurfaces. Since there is no spec could it be possible that different wayland EGL implementations will have different interpretations on if/how to reuse the wl_egl_window OR are implementations explicitly discouraged, may be to prevent themselves from blowing up in weird ways, from reusing the same wl_egl_window concurrently? Also i am assuming reuse of the wl_egl_window non-concurrently is permitted and wont have issues?</div><div class="gmail_extra"> <div class="gmail_quote">On Mon, Oct 27, 2014 at 12:36 AM, Pekka Paalanen <<a href="mailto:ppaalanen@gmail.com" target="_blank">ppaalanen@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Sat, 25 Oct 2014 17:14:32 -0700 Virtual Presence <<a href="mailto:virtualpresence.ucla@gmail.com">virtualpresence.ucla@gmail.com</a>> wrote: > Hi, > > I am writing a simple multi-threaded multi-context GLES2 Wayland client. As > required by Wayland and MESA EGL bindings i do create a wl_egl_window to > pass on to EGL window surface creation. I was wondering if there is any > spec or rule that disallows reuse of the same wl_egl_window for multiple > EGLWindowSurface. I was wondering if i could use the same underlying > wl_egl_window resize bindings to cause multiple resizes. If i cannot do the > same i would like to know of a spec/rule/guide (say like an EGL spec) that > lists all the creation, management, deletion and usage of this object. </div></div>Hi, I cannot understand what you could possibly achieve by creating several EGLSurfaces for the same window. What do you want to do? Are you perhaps attempting to render different parts of a single window in different GL contexts and so using different EGLSurfaces with some clipping magic? Maybe relying that GLX (not EGL IIRC!) required the color buffers to be shared between clients/contexts? Or do you simply want a dummy EGLSurface for each context, and then use FBOs to do the work, without ever calling eglSwapBuffers except for the one context that actually draws in the window? Because there are no Pixmaps in EGL Wayland? I can't quote a spec off-hand, but I know the EGL Wayland platform does not support "partial" rendering. Every time you call eglSwapBuffers, the whole buffer content must be valid, as the display server is free to take the whole buffer as the new window contents. That's actually a Wayland specification: every buffer must be completely drawn, as the display server is allowed to use all of it, even if the associated damage is only a part of it. So, I don't think it is explicitly forbidden anywhere to create several EGLSurfaces for the same wl_egl_window, but it just doesn't make sense. The different (E)GL contexts using the different EGLSurfaces would be fighting over whose buffer ends up on screen. As such, I expect that case to be untested, and so likely hit bugs. FWIW, you'd be looking for an EGL Wayland platform specification, and one has not been written AFAIK, as has not been written for many of the other platforms either. Thanks, pq </blockquote></div> </div>