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Re: GtkGlArea render fps is different than monitor frame rate

Ferenc, Your program's rendering is slower than the monitor nominal refresh rate, which is perfectly possible if your scenes are heavy. Please note that it could also render _faster_ (FPS higher than refresh rate). Scenes FPS are not directly tied to your monitor, unless you enable what we call "VSync" : i.e. your FPS are higher than 60, but you programmatically force it down to 60. The benefit is avoiding what we call "tearing", which is a display artifact that your eye could notice.
Tarnyko Ferenc Engárd writes:
I have a strange issue with GtkGlArea under linux: it seems my program runs
with a different fps than the monitor's refresh rate. (The rendering itself
is fast, faster than 1ms.)
I use a 60Hz monitor mode, and the rendering fps is around 39.5Hz. I
verified my monitor refresh rate with xrandr, and even with another --
X11-EGL based -- program; it is really 60Hz.
I also measured the time interval between two render calls, and the min and
max is around 22ms and 28ms, so it seems that I even do not drop a frame.
I do not set anything special in GtkGlArea or opengl (glSwapInterval or
so)... Did you encounter with such an issue? Any idea what can be the problem? Ubuntu 16.04, unity, gtk+ 3.18.9
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