[Interest] Input Latency Issues in QtQuick

[Damian Ivanov]

Hmm 2 options Jason:
a) You are not affected by the bug but are uneducated about QML (it
should run on embedded systems and slow systems too)
b) You have some sickness about hand-eye coordination.

16G, FX8320 Radeon 5750 for the bug report, do we have one yet?


2014-03-24 3:07 GMT+01:00 Jason H <scorp1us at yahoo.com>:
> Yeap, I did that. No delay.
>
> Perhaps you need a faster computer?
>
>
> ________________________________
> From: Damian Ivanov <damianatorrpm at gmail.com>
> To: Jason H <scorp1us at yahoo.com>
> Cc: Willem Bennekom <cumulatm at gmail.com>; "<interest at qt-project.org>"
> <interest at qt-project.org>
> Sent: Sunday, March 23, 2014 1:44 PM
>
> Subject: Re: [Interest] Input Latency Issues in QtQuick
>
> go to one corner and move the mouse cursor fast diagonal to the other
> corner. you will see that sometimes the rectangle is 1cm away from
> your mouse cursor.
>
> That's called delay.
>
> 2014-03-23 16:55 GMT+02:00 Jason H <scorp1us at yahoo.com>:
>> I don't have a problem with the test case.
>> AMD A6 Laptop Mint 16/64bit
>>
>> ________________________________
>> From: Damian Ivanov <damianatorrpm at gmail.com>
>> To: Willem Bennekom <cumulatm at gmail.com>
>> Cc: "<interest at qt-project.org>" <interest at qt-project.org>
>> Sent: Saturday, March 22, 2014 6:28 PM
>> Subject: Re: [Interest] Input Latency Issues in QtQuick
>>
>> hmm I can confirm the problem with the test case, depending on what
>> application you have this can be from absolutely not important to
>> quite a deal-breaker...
>> I would fill a bug.
>>
>> 2014-03-22 23:09 GMT+02:00 Willem Bennekom <cumulatm at gmail.com>:
>>> 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
>>>> >
>>>
>>>
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>
>