Bug 465024

Summary:	The opacity of the smudge brush engine does not work as expected
Product:	[Applications] krita	Reporter:	killy <80536642>
Component:	Brush engines	Assignee:	Krita Bugs <krita-bugs-null>
Status:	CONFIRMED ---
Severity:	normal
Priority:	NOR
Version First Reported In:	5.1.5
Target Milestone:	---
Platform:	Compiled Sources
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description killy 2023-01-30 03:44:06 UTC

SUMMARY
The opacity of the smudge brush engine does not work as expected 

STEPS TO REPRODUCE
1. Select a smudge brush, and set the smudge length of the smudge brush to 100% and the opacity to 50%.
2. Repeated smearing will make the opacity of the color overlap and deepen, similar to the effect of flow, which is inconsistent with the expected opacity working mode.

We can also find similar problems in these threads：
https://krita-artists.org/t/color-smudge-opacity-vs-flow/46680/8
https://krita-artists.org/t/opacity-in-smudge-brush-engine/33431

OBSERVED RESULT
https://krita-artists.org/uploads/default/original/3X/7/c/7c1939054362ef015ccf42be084747681d4b3efc.png

EXPECTED RESULT
https://krita-artists.org/uploads/default/original/3X/e/8/e8fe6e72b6737a3f331fae802eb120819ffa4b55.png

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION