1849487 - [gpu-canvas] Dotted lines appear at intersection of actual lines on a codepen demo

Status: RESOLVED FIXED

(Core :: Graphics: Canvas2D, defect)

Description

[Mayank Bansal]

enable gpu-canvas
go to https://codepen.io/zimjs/pen/qvdQqy
Let it load
click on play

AR: Lots of dotted lines appear at the intersection of lines

Regressed by : Bug 1834079 - Move stroke fallback heuristic to after we attempt AA-Stroke. r=jrmuizel

I think Bug 1834079 just allowed aa-stroke for this demo where previously we would be using non aa-stroke codepath. The actual regression would probably be from bug 1803604

Comment 1

[Mayank Bansal]

Attachment: about:support

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1803604

:lsalzman, since you are the author of the regressor, bug 1803604, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 3

[Lee Salzman [:lsalzman]]

Seems like a dup of bug 1846207.

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Bug 1841020 actually made this worse.

Comment 5

[Mayank Bansal]

This has now improved significantly with the patches from Bug 1841020 .

Some dotted lines still exist though.

Comment 6

[Mayank Bansal]

Attachment: bandicam 2023-08-29 08-00-35-866.mp4

Comment 7

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1803604

Comment 8

[Jeff Muizelaar [:jrmuizel]]

Attachment: Bug 1849487. Futher improve miter joining.

This avoids numerical stability problems when computing the
miter pointer intersection when the lines are nearly parallel.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/34dcd8f28e9a
Futher improve miter joining. r=lsalzman

Comment 10

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/34dcd8f28e9a

Comment 11

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:jrmuizel, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox118 to wontfix.

For more information, please visit BugBot documentation.

Comment 12

[Mayank Bansal]

This is fixed. Thanks Jeff!

Comment 13

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 9350720 [details]
Bug 1849487. Futher improve miter joining.

Beta/Release Uplift Approval Request

• User impact if declined: This fixes an issue introduced by bug 1841020 and overall improves the behaviour.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): If there are bugs with this code it's likely to only cause rare drawing errors when stroking paths in canvas which will not have a large impact on users.
• String changes made/needed:
• Is Android affected?: Yes

Comment 14

[Pascal Chevrel:pascalc]

Jeff, the patch doesn't graft cleanly because only one part of bug 1841020 landed in 118, the second part landed in 119. Should https://hg.mozilla.org/mozilla-central/rev/30f4abd6b2af also be uplifted? Thanks

Comment 15

[Jeff Muizelaar [:jrmuizel]]

Yes(In reply to Pascal Chevrel:pascalc (PTO until August 21) from comment #14)

Should https://hg.mozilla.org/mozilla-central/rev/30f4abd6b2af also be uplifted?

Yes. Do you want a separate uplift request?

Comment 16

[Pascal Chevrel:pascalc]

(In reply to Jeff Muizelaar [:jrmuizel] from comment #15)

Yes(In reply to Pascal Chevrel:pascalc (PTO until August 21) from comment #14)

Should https://hg.mozilla.org/mozilla-central/rev/30f4abd6b2af also be uplifted?

Yes. Do you want a separate uplift request?

No it's fine, thanks.

Comment 17

[Pascal Chevrel:pascalc]

Comment on attachment 9350720 [details]
Bug 1849487. Futher improve miter joining.

Approved for 118.0b5, also taking 30f4abd6b2af as a dependency, thanks.

Comment 18

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/88f687e1c4c9

Comment 19

[Pascal Chevrel:pascalc]

https://hg.mozilla.org/releases/mozilla-beta/rev/88f687e1c4c9