1659418 - Text flickers on 3D CSS cube with WebRender on

Status: VERIFIED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

[Rares Doghi, Desktop QA]

Attachment: 2020-08-17_14h10_56.mp4

[Affected versions]:
Nightly 81.0a1 (2020-08-16)

[Affected platforms]:
Platforms: Mac Os, Windows 10

[Preconditions]
Have gfx.webrender.all - true

Steps :

1. Launch the Firefox browser, reach https://paulrhayes.com/experiments/cube-3d/
2. Hit the UP arrow button once and then the Left arrow button twice.

Expected Results :
Text should remain static no flickers or visual glitches should occur.

Actual Results :
The Text inside the Cube flickers when the Cube rotates.

Comment 1

[Nicolas Silva [:nical]]

Dzmitry, could you have a look?

Comment 2

[Darkspirit]

First bad is 2018-09-11 (as in bug 1655732 comment 1).

Comment 3

[Dzmitry Malyshau [:kvark]]

Figured out the problem is in rectangle re-projection within get_raster_rects. It's not a plane splitting issue.

Comment 4

[Dzmitry Malyshau [:kvark]]

Attachment: wr-inverse-footprint.png

Fun looking at the inverse projection points from a rect. The interesting bit here is one of the points in the left top corner.

Comment 5

[Dzmitry Malyshau [:kvark]]

Attachment: cube.html.zip

Reduced test case (has HTML and a few CSS)

Comment 6

[Dzmitry Malyshau [:kvark]]

Attachment: Handle inverse projection negative hemisphere

Our inverse projection logic was correct, just not fully complete.
The problem is that it didn't take into account that the projected point can be in negative hemisphere.
Now we are checking for this and bailing out of building a tight rect if this is the case.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cc76c766bd81
Handle inverse projection negative hemisphere r=nical

Comment 8

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/cc76c766bd81

Comment 9

[Rares Doghi, Desktop QA]

This issue is Verified as fixed in our Latest Beta build 83.0b4 on Windows as well as Mac osX 10.15.