[Interest] Input Latency Issues in QtQuick

[Willem Bennekom]

For me, the lagging is clearly noticeable on all platforms where vsync is
enabled.
(Macbook Pro (Nvidia), Linux/Windows Desktop with Nvidia, Windows Desktop
with AMD + Angle.
It hapopens with all Qt Quick versions.)

Here's a minimal test scene (rectangle follows mouse):
http://pastie.org/pastes/8959817

2014-03-22 18:37 GMT+01:00 Damian Ivanov <damianatorrpm at gmail.com>:

> for the record: I can't confirm this, QML input is instantly here free
> radeon driver (5series) on openSUSE 13.1 64bit.
>
> 2014-03-22 15:46 GMT+01:00 Willem Bennekom <cumulatm at gmail.com>:
> > With its current architecture, QtQuick has input latency issues:
> > The scene reacts to user input with a slight, but noticeable delay, which
> > makes
> > QtQuick apps feel clumsy and unpleasant to use.
> >
> > I guess this is related to vsync handling, where input events don't
> > immediately
> > trigger a repaint while the render thread waits until the framebuffer is
> > swapped.
> >
> > The only exception are Windows platforms with native OpenGL on ATI cards,
> > where the framerate seems to be uncapped:
> > The rendering is super responsive, almost like Qt Widgets.
> > The drawback is that render thread animators are broken, as they aren't
> > synced to 60 Hz.
> >
> > 1. Is there a way to hack Qt to get this Windows+OpenGL+ATI rendering
> > behavior on all platforms?
> >    Maybe some tweaks in qsg*renderloop.cpp?
> >
> > 2. Are there plans to implement a rendering scheme that reduces input
> > latency?
> >
> > Thanks
> > Willem
> >
> > _______________________________________________
> > Interest mailing list
> > Interest at qt-project.org
> > http://lists.qt-project.org/mailman/listinfo/interest
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20140322/4942ac31/attachment.html>