[Interest] Reduce maximum frame rate with Qt5.3 beta

[Sean Harmer]

On Sunday 20 April 2014 02:50:50 Joshua Kolden wrote:
> On Apr 20, 2014, at 1:39 AM, Sean Harmer <sean.harmer at kdab.com> wrote:
> > The swapInterval() mentioned by Laszlo combined with this controls the
> > refresh rate in the common case.
> > 
> > Setting swapInterval to:
> > 
> > * 1 enforces vsync
> > * 0 turns vsync off
> > * -1 uses adaptive vsync (if framerate is > rfresh rate then use vsync. If
> > framerate is < refresh rate do not wait for vsync).
> > 
> > See http://www.opengl.org/wiki/Swap_Interval for more info.
> > 
> > Of course all of this can be overriden by the user if they force some
> > settings in the driver's control panel.
> 
> That’s interesting.  That’s almost exactly the opposite of the way I’d
> expect it to work (i.e. default to card / app can override). So what’s the
> default setting? That link doesn’t seem to say.

As Laszlo mentioned, Qt defaults to using vsync. But the driver settings can 
override this. It works like this as some people like to force (no) vsync in 
games even if the game doesn't offer such a setting.

Within Qt you should have vsync working, if it is not check the driver 
settings. If you want to turn vsync off within Qt then 
QSurfaceFormat::setSwapInterval(0) should do it. Of course where you use this 
depends upon your particular application. If it's for a QQ2 app then create a 
surface format including the above setting and call setFormat() on the 
QQuickView.

Cheers,

Sean


> > Cheers,
> > 
> > Sean
> > 
> > --
> > Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> > Klarälvdalens Datakonsult AB, a KDAB Group company
> > Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
> > KDAB - Qt Experts - Platform-independent software solutions
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--
Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
Klarälvdalens Datakonsult AB, a KDAB Group company
Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
KDAB - Qt Experts - Platform-independent software solutions