1552754 - Thin subpixel border radius is more aliased with WebRender enabled

Status: REOPENED

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

Description

[Kestrel]

Attachment: Comparison with Webrender disabled (left) and enabled (right)

WebRender causes the ProtonMail loading animation to appear more pixelated.

Comment 1

[Kestrel]

Attachment: protonmail-loading.html

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Interesting. The logo is made up of 3d transformed surfaces. It isn't obvious to me why there we would be a difference in how WebRender vs not draws this.

Comment 3

[Glenn Watson [:gw]]

Test case doesn't seem to load for me - still an issue?

Comment 4

[kanapa1]

Over time, the Proton Mail loading screen has been changed many times. Today it shows a P-shaped icon with no animations or transformations (it is the same as the one used as a favicon on most Proton pages). Therefore, it is now displayed correctly and with proper anti-aliasing, so instead of the author of this bug, I can confirm that this is no longer an issue.

Comment 5

[Mayank Bansal]

Closing per last comment.

Comment 6

[Kestrel]

Attachment: test-case.html

New test case. The issue occurs with a border radius that transitions to 0px width or is 3D rotated so that the border is rendered at subpixel width.

Comment 7

[Kestrel]

Attachment: Comparison of border radius aliasing between Basic and Webrender compositor, bottom ring is 3D rotated

Comment 8

[Kestrel]

Attachment: Comparison of border radius aliasing between Webrender and Chrome, bottom ring is 3D rotated

Chrome has less severe aliasing for the non-rotated case compared with Webrender, with the border color fading more smoothly into the background. Both browsers produce significant aliasing for the 3D rotated case compared with non-Webrender which has a dithered appearance.