Bug 515568 - The blur effect updates only partially
Summary: The blur effect updates only partially
Status: CONFIRMED
Alias: None
Product: kwin
Classification: Plasma
Component: effects-various (other bugs)
Version First Reported In: 6.5.5
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2026-02-05 18:56 UTC by fililip
Modified: 2026-02-09 23:37 UTC (History)
2 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
blur effect artifact (1.58 MB, image/png)
2026-02-05 18:57 UTC, fililip
Details

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Description fililip 2026-02-05 18:56:09 UTC
SUMMARY
The blur effect updates only partially for a surface, which is especially noticeable during video playback and low blur intensity + high opacity values

STEPS TO REPRODUCE
1. Edit /usr/share/plasma/desktoptheme/default/plasmarc to remove the contrast effect for better visibility (set it to false)
2. Reload the Breeze theme
3. Set the blur and noise strength values to the 7th position
4. Open a window that's constantly updating (like Firefox/Chromium/whatever playing a video)
5. Open Konsole, enable the background blur effect and set the background opacity to ~40-50%
6. Move the Konsole window so that it's on top of the updating window but doesn't fully cover it

OBSERVED RESULT
There is a seam where the blur effect "cuts off" where the underlying window's edges end due to partial effect repaints

EXPECTED RESULT
There should be no seam visible at all

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.2
Kernel Version: 6.18.7-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800X 8-Core Processor
Memory: 64 GiB of RAM (62.7 GiB usable)
Graphics Processor: AMD Radeon RX 9070
Comment 1 fililip 2026-02-05 18:57:57 UTC
Created attachment 189250 [details]
blur effect artifact

Here's what the artifact looks like
Comment 2 Zamundaaa 2026-02-09 23:37:32 UTC
IIRC some damage tracking changes meant the blur effect doesn't expand the repaint area like it used to anymore. We need to find out how to solve that better.