Re: [Bug-gnubg] Vsync?

[Jonathan Kinsey]

Hi Rich,

Coincidently I have been looking at this recently!  What is interesting is that
your results seem wrong.  In that 200fps isn't better than 60fps, this is
because your monitor is set to display only 60fps (so 140 frames are needlessly
drawn and not shown).

You are right in that vsync should generally be turned off (and I'm about to add
an option for this - on windows at least), openGL defaults to vsync on - this
can generally be overridden by settings in the graphics card or by applications
themselves.  The problems with turning it off is "tearing", this is where a new
frame is drawn half way through a monitor refresh (so you get half of one frame
and half of the next), in gnubg the frames are static so this problem isn't an
issue.  The other less important problem is overdrawing (drawing more frames
than can be shown), you can add throttling for this but I'm not going to at the
moment.

Back to your email and I wonder if you have shadows enabled when you run the
test in gnubg?  There is a handy little utility called FRAPS, if you download
that it should display the number of fps being shown when the dice are rolled
for example.

Ideally there would be more feedback on the performance test, this may come
later.  Hopefully I'll check my current changes in soon (as well as he vsync
option I've added some code to try and speed up the drawing).

Jon

Rich Heimlich wrote:
> Guys, we've gotten to the bottom of something with GNUBG and Nvidia cards.
> 
> I couldn't, for the life of me, figure out why my supposedly blazing
> fast new 8800 card could only get 60fps in the Test Performance in the
> game. I then got on the Rage3D forums and finally got some Nvidia guys
> looking at this (I've been ATI forever) and they nailed the issue. By
> default gamers have Vsync set to Application Preference. Due to an issue
> in Flight Simulator it's recommended to set it to FORCE OFF. When I do
> that with GNUBG my performance shoots through the roof to 200fps (and
> more) and it plays smooth as glass. With that set to app preference even
> at 60fps the dice rolls and movement are choppy about 40% of the time.
> 
> After testing a bit it seems the program is forcing Vsync ON.
> 
> Is this accurate and, if so, is there a reason for it? Can we get an
> option that allows the app to turn it off so that I don't have to force
> it off?
> 
> It might also be helpful of Test Performance were enhanced a bit to
> bring up its own screen to explain some things that are addressed and
> other things that can be done to help improve performance. If I were
> pointed to Vsync I could have save a lot of poking around for a long time.
> 
> 
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