Bug 476304

Summary: Wiggle at start of line with 2-point-perspective assistant
Product: [Applications] krita Reporter: Rebecca Breu <rebecca>
Component: Tool/AssistantsAssignee: Krita Bugs <krita-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: lynx.mw+kde, prbardin
Priority: NOR Keywords: regression
Version: 5.2.0   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:
Attachments: Screenshot of wiggles
Example kra file with assistants set up

Description Rebecca Breu 2023-10-29 21:47:21 UTC
Created attachment 162704 [details]
Screenshot of wiggles

I've set up a 2-point-assistant and a vanishing point. If I draw a line with snap to assistant that's supposed to snap to the 2-point assistant, the start of the line often has a small wiggle. "Snap to single line" is activated. See screenshot.

Drawing the same line in the reverse direction usually doesn't get a wiggle. Snapping to the single vanishing point doesn't produce any wiggles. If I remove the single vanishing point, no wiggles either. If I go back to Krita 5.1.5, no wiggles either with the same setup of assistants.
Comment 1 Rebecca Breu 2023-10-29 21:48:25 UTC
Created attachment 162705 [details]
Example kra file with assistants set up
Comment 2 Rebecca Breu 2023-10-29 22:02:05 UTC
Playing around with it further, I think the line wants to snap to the single vanishing point first before it decides to latch onto the 2-point assistant. Only that I have "Snap to single line" enabled where it should stick with the line first snapped onto. The less precise I am with my line, the bigger the wiggle. For some lines, it's almost impossible to be precise enough to not get a wiggle at all.
Comment 3 Rebecca Breu 2023-11-13 16:37:40 UTC
Another user has reported the same behaviour on KA:

https://krita-artists.org/t/problem-with-combining-2-points-perspective-vanishing-point-assistants-in-version-5-2-1/77984/2

I've further found it's not only the 2-point perspective assistant that's causing this, just the one most likely/frequent to behave like this.
Comment 4 Lynx3d 2024-02-27 22:17:18 UTC
Seems I didn't properly look for bug reports, I wasn't even aware it regressed from 5.1.5.

Can you test with current master? The old setup for nightly builds is gone unfortunately, you currently have to click your way through https://invent.kde.org/graphics/krita/ to download a CI "pipeline artifact" of the last successful build (that hopefully hasn't been deleted yet).

If no one finds regression compared to 5.1, we need to backport https://invent.kde.org/graphics/krita/-/merge_requests/2066  to 5.2 I guess.
Comment 5 Rebecca Breu 2024-03-02 15:11:36 UTC
Yeah, the wiggles are gone now. I tested with the file I had attached to this bug report, and also another file where I tried out my most frequent use cases. Overall, it works well for me now.
Comment 6 Lynx3d 2024-03-05 09:54:29 UTC
Thanks for testing.
Backported to 5.2 branch, so it should be in 5.2.3
(commits b70eaea4 to 5db332f8)