Discussion:
[krita] [Bug 357765] New: Brush lag / slowdown for some rotation/zoom combinations
via KDE Bugzilla
2016-01-09 22:37:51 UTC
Permalink
https://bugs.kde.org/show_bug.cgi?id=357765

Bug ID: 357765
Summary: Brush lag / slowdown for some rotation/zoom
combinations
Product: krita
Version: 2.9.10
Platform: MS Windows
OS: MS Windows
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: general
Assignee: krita-bugs-***@kde.org
Reporter: ***@live.fr

This problem happens on a rather old machine (athlon 64 6400+x2, 4GB memory,
AMD radeon 4670 HD [but still appeared with a NVidia 630 GT]), on which brush
movement is still usually perfectly smooth.

When OpenGL is activated and canvas is rotated, at some high zoom range (e.g
1000% to 1500% for a 4096x4096 canvas, though these values seems to vary), the
brush become laggy and its position update can become as slow as two or three
per seconds, except is rotation value is /near/ 0, 90, 180 or 270 (±5°) , in
which case no slowdown is visible. Sometimes, the problem also disappears at
very high zoom values (2000+) and is never present at all for small zoom values
(<1000).

Using texture buffer or not, changing interpolation mode has no influence.

However, this never happens when OpenGL is disabled, no lag is to report.
However, it makes zooming and rotating so slow that it doesn't represent the
best workaround.

Reproducible: Always

Steps to Reproduce:
1. Open Krita x64, create a 4096x4096 canvas (tested in 8-bit grayscale, with a
white canvas color)
2. Be sure to use OpenGL for canvas rendering
3. Do some scribbling to see the canvas zoom/rotations with the classical pen
tip brush.
4. Rotate a bit (~30°), zoom in slowly, while being attentive to the fluidity.
5. When lag starts to become noticeable, stop zooming and try to draw some
lines, the brush should be laggy.
5. Rotate near 0° while keeping the same zoom value, check the brush fluidity
again, it should be perfectly responsive now.


Actual Results:
Near 1000+, the canvas starts to lag during zoom itself , and it will lag more
and more until reaching a certain zoom value and instantly become responsive
again.

Right before this value, the canvas will lag the most, and brush is near
unusable, until the canvas is rotated to an almost horizontal/vertical angle,
in which case lag disappears entirely.

Expected Results:
Well, being responsive for every zoom/rotation values, since the lag phenomenon
isn't always present, only when certain conditions are met.

The configuration :
Athlon 6400+x2
AMD radeon 4670 HD (formerly a NVidia 630 GT)
4GB memory
Running Windows 7 Professionnal Edition 64 bits
Using a Wacom Intuos Creative Pen & Touch and Krita 2.9.10 (labelled 2.9.9 on
splash screen) 64 bits
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Boudewijn Rempt via KDE Bugzilla
2016-01-10 10:43:20 UTC
Permalink
https://bugs.kde.org/show_bug.cgi?id=357765

Boudewijn Rempt <***@valdyas.org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEEDSINFO
Resolution|--- |WAITINGFORINFO
CC| |***@valdyas.org

--- Comment #1 from Boudewijn Rempt <***@valdyas.org> ---
Hi,

Thanks for your report. I'm afraid that there isn't a whole lot we can do,
though. From your description it's definitely an issue with the combination of
krita, your GPU and driver. I'm suspecting that at high zoom levels, the GPU
has trouble scaling the textures. You could try other settings for the scaling
method, that might help.
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via KDE Bugzilla
2016-01-10 21:15:09 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

--- Comment #2 from ***@live.fr ---
(In reply to Boudewijn Rempt from comment #1)
Post by Boudewijn Rempt via KDE Bugzilla
Hi,
Thanks for your report. I'm afraid that there isn't a whole lot we can do,
though. From your description it's definitely an issue with the combination
of krita, your GPU and driver. I'm suspecting that at high zoom levels, the
GPU has trouble scaling the textures. You could try other settings for the
scaling method, that might help.
Hello,

Thank you for your quick answer. Are you sure about the GPU, though? I just
checked with a slighly different rig (3GB memory, windows vista 64 bits, AMD
Athlon64 x2 5050e) equipped with the said Nvidia GT 630 and the issue is
exactly the same. No access to a recent / Intel machine alas. Also, it's
probably an issue with the GPU and texture scaling, but the lag abruptely
disappear past a certain, very high zoom level, which is quite weird...
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via KDE Bugzilla
2016-01-10 21:17:11 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

--- Comment #3 from ***@live.fr ---
Also I forgot to say, that changing the scaling mode has no influence on the
lag. Sorry for the double post.
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via KDE Bugzilla
2016-01-11 12:01:12 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

--- Comment #4 from ***@live.fr ---
In fact, I got access to a recent, i7 powered computer ( windows 8, 16gb
memory, NVIDIA 680 GTX) and the issue is still here. It's just less noticeable
because the machine capabilities will compensate for the performance drop.
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Raghavendra kamath via KDE Bugzilla
2016-04-09 07:00:02 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

Raghavendra kamath <***@gmail.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
CC| |***@gmail.com

--- Comment #5 from Raghavendra kamath <***@gmail.com> ---
I think this is solved please check this bug report which sounds similar -
https://bugs.kde.org/show_bug.cgi?id=355104 . try the new alpha releases to
test if this issue persists. If it is solved we can close this.
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via KDE Bugzilla
2016-04-19 22:17:35 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

--- Comment #6 from ***@live.fr ---
According to the description, this issue was the same as mine.

And I just checked the Krita 3.0 alpha builds for windows, the problem doesn't
appear anymore ! Thanks to everyone who worked on it, and took the time to
review this bug report.
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Raghavendra kamath via KDE Bugzilla
2016-04-20 04:21:50 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

Raghavendra kamath <***@gmail.com> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDSINFO |RESOLVED
Resolution|WAITINGFORINFO |DUPLICATE

--- Comment #7 from Raghavendra kamath <***@gmail.com> ---
Thanks closing this bug report then :)

*** This bug has been marked as a duplicate of bug 355104 ***
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via KDE Bugzilla
2016-04-21 21:00:30 UTC
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https://bugs.kde.org/show_bug.cgi?id=357765

***@live.fr changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |CLOSED
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2016-04-21 21:01:27 UTC
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--- Comment #8 from ***@live.fr ---
Whoops, fixed.
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