Bug 419368

Summary:	Line Tool: Lines jagged/wiggly on pixel layers
Product:	[Applications] krita	Reporter:	Rebecca Breu <rebecca>
Component:	Tools	Assignee:	vanyossi <ghevan>
Status:	RESOLVED FIXED
Severity:	normal	CC:	griffinvalley
Priority:	NOR	Keywords:	regression
Version First Reported In:	4.2.9
Target Milestone:	---
Platform:	Debian stable
OS:	Linux
Latest Commit:	https://invent.kde.org/kde/krita/commit/e73f8220f6170c56b833f5c932800f7f6acc91c5	Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Wiggly lines in 4.2.9 Straight lines in 4.2.8

Description Rebecca Breu 2020-03-29 10:56:25 UTC

Created attachment 127080 [details]
Wiggly lines in 4.2.9

SUMMARY

When the straight line tool is used on a pixel layer, the lines aren't quite straight, but a little jagged/wiggly.


STEPS TO REPRODUCE
1. Create a new image with a pixel layer
2. Select a thin line art brush
3. Select the line tool
4. Draw lines

OBSERVED RESULT

Lines are a little jagged / wiggly. See screenshots.

EXPECTED RESULT

Straight lines.


This happens only with 4.2.9, not with 4.2.8. A user reported this on reddit first:

https://www.reddit.com/r/krita/comments/fqnjnw/straight_line_tool_bug/

Comment 1 Rebecca Breu 2020-03-29 10:56:50 UTC

Created attachment 127081 [details]
Straight lines in 4.2.8

Comment 2 wolthera 2020-03-29 11:18:42 UTC

Probably related to ivanyossi's 1px fix. I'll assign him.

Comment 3 vanyossi 2020-04-14 06:16:58 UTC

Git commit 76fa0fe0b87c7c83ff8c4c5b527debcd18c7271a by Ivan Yossi.
Committed on 14/04/2020 at 06:16.
Pushed by ivany into branch 'master'.

Adjust line points to DDA only to pixel size brushes

By adjusting to pixel level we loose subpixel precision
and lines appear jagged/curved

M  +1    -2    plugins/tools/basictools/kis_tool_line_helper.cpp

https://invent.kde.org/kde/krita/commit/76fa0fe0b87c7c83ff8c4c5b527debcd18c7271a

Comment 4 vanyossi 2020-04-14 06:18:13 UTC

Git commit e73f8220f6170c56b833f5c932800f7f6acc91c5 by Ivan Yossi.
Committed on 14/04/2020 at 06:17.
Pushed by ivany into branch 'krita/4.3'.

Adjust line points to DDA only to pixel size brushes

By adjusting to pixel level we loose subpixel precision
and lines appear jagged/curved

M  +1    -2    plugins/tools/basictools/kis_tool_line_helper.cpp

https://invent.kde.org/kde/krita/commit/e73f8220f6170c56b833f5c932800f7f6acc91c5