On Wed, Mar 7, 2012 at 8:34 AM, Kristian Høgsberg <[email protected]> wrote: > On Mon, Mar 5, 2012 at 2:42 AM, Pekka Paalanen <[email protected]> wrote: >> On Sun, 4 Mar 2012 20:37:48 -0800 >> Mandeep Singh Baines <[email protected]> wrote: >> >>> Hi, >>> >>> I have recently started playing around with EGL_PLATFORM=drm. Using >>> eglkms.c and compositor-drm.c as examples, I've been able to port some >>> simple EGL/GLESv2 applications without much effort. But the one weird >>> thing is that everything gets rendered upside down and backwards. I >>> guess I could solve this with the projection matrix but just wondering >>> why I'm getting this effect. How does compositor-drm deal with this. >> >> Look for WL_OUTPUT_FLIPPED in weston. >> >> I guess and if I remember right, flipped y-axis is because OpenGL >> back/front buffer of a window has origin at top-left with y growing >> down, but FBOs have origin at bottom-left with y growing up. Or maybe >> it was vice versa, I didn't check. > > I'm actually not sure about this. For a while I thought that GL > framebuffer objects had a different coordinate system (origin in upper > left), but Robert Bragg recently pointed out to me that that was just a > mesa optimization. Which could be true and I wasn't able to find > anything in the FBO spec about the coordinate system. > > Either way, there isn't currently anything you can do, except render > upside down. We do have a new interface planned, that will let you > create a struct gbm_surface, which you can then create an EGLSurface > from. That way it's going to be a "system fbo" internally in mesa and > the coordinate system is going to what you expect. It will also > remove the need for the surfaceless extension (since now we have a
I think you could remove the need for the surfaceless extension even now. In Chromium, we use a 1x1 Pbuffer surface for such contexts. > real EGLSurface). The API will let you "lock" the surface frontbuffer > after a swap, which gives you a gbm_bo which you can then pageflip to. > It's going to require mesa master, but I hope we can land it within > the next couple of weeks. > > http://cgit.freedesktop.org/~krh/mesa/log/?h=gbm_surface > > Kristian _______________________________________________ wayland-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/wayland-devel
