Hi; On 3 October 2016 at 21:54, Sébastien Le Roux <sebastien.ler...@ipcms.unistra.fr> wrote:
> Hello everyone and thanks for reading this, > You will find the same message posted on stackoverflow by following this > link > <http://stackoverflow.com/questions/39837159/gtk2-vs-gtk3-signal-expose-draw-render-events> > (or pretty much the same), > but I figured that the gtk mailing list was probably a better way to get the > help I need. > My name is Sébastien Le Roux, I am working on a program that offers a > visualization interface for molecules, > atomic systems ... I have 3 different versions of my program: > > * (a) GTK2 + GtkGlext : works great ! > * (b) GTK3 + X11 : works just fine ! > * (c) GTK3 + GtkGLArea : does not work :-( By "GtkGLArea" I assume you mean the GtkGLArea widget that GTK+ provides since 3.16: https://developer.gnome.org/gtk3/stable/GtkGLArea.html But you'll have to define "does not work". I also have no idea how you're using OpenGL on GTK+ without GtkGLArea — I assume you're just creating a custom widget with a GdkWindow backed by a native X11 surface, and then just creating a GLX context with that. That's not really supported, and it only happens to work because projects like Clutter still use this approach and we cannot really change them. > While I am still working on (c), I learned that the GtkGLArea is rather > picky concerning the OpenGL commands, GtkGLArea is not "picky": as the documentation says, GtkGLArea supports OpenGL 3.2+ core profile contexts by default, and only falls back to OpenGL compatibility profiles if the GL stack does not support GL versions ≥ 3.2 (starting from GTK+ 3.20). > some things came up while I was trying > to find out the origin of some behavior differences between (a) and (b). The > OpenGL rendering is significantly slower in (b) than in (a), or I thought > that was the case. How do you measure "slowness"? > If you check this link > <http://stackoverflow.com/questions/39789414/how-to-get-as-many-information-as-possible-about-an-opengl-context> > you will see that I got some help and manage to find out that GTK+ signals > were not handled in the same way between GTK+2 (a) and GTK+3 (b), and (c) Yes, they most definitely do not match because GdkGLContext and GtkGLArea use the GTK+ drawing cycle instead of just rendering to a native surface that may or may not end up on the screen. This allows GtkGLArea to have popovers that blend with the contents below, or semi-transparent widgets on top of the GL content, unlike the "native rendering" approach, which does not allow either. > Using the tool Apitrace I noticed in case (a) that each OpenGL frame was > drawn once, while it was drawn 5 times in cases (b) and (c). Then just > adding a basic counter in the callback I confirmed that for each > "expose/draw/render" the signal was emitted (and thus the "drawing-area" was > rendered that many times, for the same frame): You're comparing two fundamentally different toolkits — GTK+ 2.x and GTK+ 3.x. The rendering process has been completely changed since the 2.x days, so it's literally pointless to draw a comparison. You're also trying to compare rendering done out of order, on a separate windowing system surface, with an integrated rendering pipeline that includes OpenGL. In general, GTK+ only draws what needs to be drawn, including specific regions. This may lead to multiple calls to ::draw(), or, in case of GtkGLArea, multiple calls to ::render(), though multiple invalidations are generally coalesced together. You can get a quick overview of how GTK+ draws from this blog post: https://blog.gtk.org/2016/06/15/drawing-in-gtk/ > (a) is GTK+2, (b) and (c) are GTK+3 ... now my question will be rather > obvious, but how can I changed or maybe should I say correct the GTK+3 > version of my program to make it as smooth, on an OpenGL rendering point of > view, as the GTK+2 version ? It's likely you're rendering too much yourself; for instance, you may be constantly queueing redraws in the middle of a render(), by changing widget states; or, worse, you could be queueing a whole relayout during rendering. Without knowing what you're doing inside your code, there's not enough context to give you a sensible answer. Ciao, Emmanuele. -- https://www.bassi.io [@] ebassi [@gmail.com] _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
