1841020 - Artifacts when rendering mitered paths

Status: VERIFIED FIXED

(Core :: Graphics: Canvas2D, defect, P2)

Description

[Calixte Denizet (:calixte)]

Attachment: test_miter.pdf

It's a mirror bug of:
https://github.com/mozilla/pdf.js/issues/16619

There are some artifacts when rendering the path.
It's ok with gfx.canvas.accelerated set to false.

:lsalzman, any idea ?

Comment 1

[Mayank Bansal]

Regression range:
Bug 1803604 - Use aa-stroke to accelerate stroked paths in Canvas2D. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D163609

Comment 2

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

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

Comment 3

[Lee Salzman [:lsalzman]]

Jeff, this looks like a bug in aa-stroke itself. Repros on Linux too (reporter on Mac). Doesn't appear to be driver specific.

Comment 4

[Lee Salzman [:lsalzman]]

Calixte, can this please me made into a standalone, non-pdf testcase, just calling directly into Canvas2D? That would make it easier to debug. The PDF is pretty opaque.

Comment 5

[Calixte Denizet (:calixte)]

Attachment: bug1841020.html

Comment 6

[Calixte Denizet (:calixte)]

On mac, with 114.0.2, the attached html is ok but the pdf is not...
With nightly, both test cases have the artifacts.

Comment 7

[Calixte Denizet (:calixte)]

Attachment: bug1841020_reduced.html

Here's a very reduced test case.
The artifacts are two thin dotted lines tangent to the bezier curves.

Comment 8

[Calixte Denizet (:calixte)]

I just tested the three test cases on Windows 11 with gfx.canvas.accelerated set to true, and all of them are showing the artifacts.

Comment 9

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

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

Comment 10

[ccampbell]

Attachment: en-roads-1.png

(I'm adding this comment in case the linked En-ROADS example is useful in verifying the eventual fix for the underlying issue. I didn't think it warranted it's own issue since the underlying problem seems the same; apologies if piling on to an existing issue is bad form.)

I believe this is the same issue that we are encountering in En-ROADS, where there are sporadic rendering artifacts seen on certain line graphs. See attached screenshot (en-roads-1.png).

This started appearing after upgrading to Firefox 115 (I'm on macOS). The bug appears only at certain window sizes. It can be reproduced by slowly changing the browser window width.

I verified that the bug does not appear after disabling the new aa stroke renderer flag (gfx.canvas.accelerated.aa-stroke.enabled = false). Unchecking the "Use hardware acceleration when available" setting also has the same effect, as expected.

Comment 11

[Jeff Muizelaar [:jrmuizel]]

It looks like there's some numerical instability around miter joins. I hope to solve it by the end of the week.

Comment 12

[Jeff Muizelaar [:jrmuizel]]

Attachment: Bug 1841020. Improve miter joining.

This updates aa-stroke to fef8702c4c8afd7d47e7a5aafb6fa347c96b50be
which fixes some degenerate behaviour when mitering parallel lines.

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/efeef29d315b
Improve miter joining. r=lsalzman

Comment 14

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/efeef29d315b

Comment 16

[Cristian Tuns]

Backed out as requested by jrmuizel

• Backout link

Comment 17

[Jeff Muizelaar [:jrmuizel]]

Backed out for making bug 1849487 worse.

Comment 18

[Mayank Bansal]

FWIW, the reduced testcase did improve with the (now backed out) patch. But the original pdf still has those dotted lines that appear-disappear at different zoom levels, and become permanent after a certain zoom level (300% on my machine)

Comment 19

[Iulian Moraru]

Backout merged to central: https://hg.mozilla.org/mozilla-central/rev/cc8d561a9b40

Comment 20

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/cc8d561a9b40

Comment 21

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/30f4abd6b2af
Improve miter joining. r=lsalzman

Comment 22

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/30f4abd6b2af

Comment 23

[Mayank Bansal]

(In reply to Mayank Bansal from comment #18)

FWIW, the reduced testcase did improve with the (now backed out) patch. But the original pdf still has those dotted lines that appear-disappear at different zoom levels, and become permanent after a certain zoom level (300% on my machine)

This is still true. The original pdf still has dotted line artifacts.

Comment 24

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/5443eeeb53b9

Comment 25

[Pascal Chevrel (relman team) -> :pascalc]

https://hg.mozilla.org/releases/mozilla-beta/rev/5443eeeb53b9

Comment 26

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Reproducible on a 2023-08-24 Nightly build on macOS 12.
Verified as fixed on Firefox 119.0b2(build ID: 20230928191344) and Nightly 120.0a1(build ID: 20230928215127) on macOS 12, Windows 10, Ubuntu 22.