https://bugs.kde.org/show_bug.cgi?id=386620
Bug ID: 386620
Summary: Canvas framerate limiter might not be working as
intended
Product: krita
Version: 4.0 pre-alpha
Platform: MS Windows
OS: MS Windows
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: OpenGL Canvas
Assignee: krita-bugs-n...@kde.org
Reporter: nevinevi...@yahoo.com
Target Milestone: ---
Krita 4.0 pre-alpha (git 86851fa) exposes to the user a frame limiting function
under "Settings > Configure Krita > Performance > Advanced > Limit Frames per
Second while painting".
After fiddling around with it for a while, trying different settings (making
sure to restart the program to apply the new values), I came to the conclusion
that the frame limiting function might not be working as intended, producing as
a result an *effective* canvas update framerate that is roughly (slightly more
than) half the user set value.
==How to observe it?==
1) Try setting a low frame limit value, like for example 20 fps.
2) Reboot Krita.
3) Create a new image and proceed to recording a short video capture of the
desktop/program at the frame rate of the display frequency rate (typically 60
Hz) using for example the open source OBS (Open Broadcast Studio) software, and
a small brush at 100% canvas zoom in order to avoid any GPU bottleneck issue.
4) The framerate of the canvas in Krita can then be easily analyzed using a
standard video player (e.g. VLC) advancing the video frame by frame.
==Results==
At a Krita canvas fps of 20 fps, and a video framerate of 60 fps, brush strokes
and the brush cursor appear to update roughly every 5 or 6 frames (sometimes 4
or 7). This corresponds to an *effective* canvas frame rate of 10-12 fps, which
is significantly lower than the user set value.
At a Krita canvas fps of 60 fps (equivalent to the display refresh rate) and
again a recording video frame rate of 60 fps, bursh strokes appear to update
most of the time 2 frames, less often every frame. In a test, the canvas
updated 44 times over the course of 69 frames, implying an actual framerate of
about 38 fps. That the canvas updates at a much lower rate than the screen
refresh rate is also subjectively noticeable by eye during ordinary program
operation.
==System configuration==
Windows 10 64bit Fall Creators Update
AMD Radeon RX480 with Radeon Software 17.11
Intel i5 3550 4-core GPU.
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