Re: recommended way to create a render loop with gtkglext

["Brian J. Tarricone" <bjt23 cornell edu>]

Chris H wrote:
> Hello,
> I'm writing a GLSL shader editor and I need to be able to create a loop that
> will force the gtkglext widget to constantly refresh at 60Hz or less if the
> frames take too long to render. I've tried to copy the code from the
> logo.cexample but it just isn't refreshing. Honestly I'd rather stay
> away from
> g_timeout for this task. I tried using threads but it became really unstable
> (segfaults) when calling
>   /* Invalidate the whole window. */
>   gdk_window_invalidate_rect (widget->window, &widget->allocation, FALSE);
>
>   /* Update synchronously. */
>   gdk_window_process_updates (widget->window, FALSE);
> in the separate thread. Is there a way I could simply have the separate
> thread send a redraw signal to the widget, and would that event work? I'm
> open to just about any ideas that don't involve g_timeout.

gdk_window_invalidate_rect() *is* the way to send a redraw signal to the 
widget's underlying GdkWindow.  Give gtk_widget_queue_draw_area() a try 
instead.

If you're calling this from a separate thread, be sure you've 
initialized gthread (with g_thread_init()) and gdk's locking (with 
gdk_threads_init()) before gtk_init() in main().  You'll need to 
surround your call to gtk_main() with gdk_threads_enter() and 
gdk_threads_leave(), and you'll have to do the same for any gtk/gdk 
calls you make in other threads.

Alternatively, you can *not* initialise gdk's threading at all, and use 
g_idle_add() from your worker thread to schedule a function to call 
gtk_widget_queue_draw_area() (the idle function will run in the main 
thread, regardless of where you call g_idle_add()).

        -brian