1491911 - Extreme 3d-perspective Melts Webrender

Status: RESOLVED FIXED

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

Description

[Aria Beingessner [:Gankra]]

Attachment: perspective.html

I noticed this when messing around with the perspective on https://developer.mozilla.org/en-US/docs/Web/CSS/perspective

Attached is a more reduced case that reliably creates corrupted rendering that extends into the chrome.

Comment 1

[Aria Beingessner [:Gankra]]

Attachment: 3d-wr.PNG

rendering in wr on my windows nvidia laptop

Comment 2

[Aria Beingessner [:Gankra]]

Attachment: 3d-ff.PNG

rendering in vanilla firefox

Comment 3

[Emilio Cobos Álvarez (:emilio)]

(I see the expected thing here on Linux FWIW)

Comment 4

[Aria Beingessner [:Gankra]]

This is obscure enough that we could probably go to beta with it, but nasty enough that I wouldn't be opposed to bumping this to P1.

Comment 5

[Aria Beingessner [:Gankra]]

I also see the tearing corruption on my nvidia/nouveau linux desktop, although much harder to get chrome corruption.

Comment 6

[Darkspirit]

Debian Testing, GTX 1060
https://addons.mozilla.org/en-US/firefox/addon/starry-space-fantasy/
Nightly should be renamed back to "Minefield". Depending on zoom level and theme, I get every behavior, incl. drawn on tabs. ;)

Comment 7

[Glenn Watson [:gw]]

I can reproduce this on Linux w/ nvidia (blob) driver. The same machine with Intel GPU enabled doesn't show the artifact. It looks like uninitialized data / garbage or perhaps NaN output from the shaders?

I'll take this one - I think I have seen a similar looking screenshot in a few bugs, so it's probably worth sorting out now.

Comment 8

[Patrick Walton (:pcwalton)]

Looks OK to me on macOS/Intel.

Comment 9

[Glenn Watson [:gw]]

This appears to be either a driver/shader compiler bug, or perhaps some internal precision implementation detail we're seeing on certain GPUs only.

I have a fix / workaround for it, but making sure the fix doesn't break any existing reftests may take a little while.

Comment 10

[Glenn Watson [:gw]]

Fix is https://github.com/servo/webrender/pull/3073.

Comment 11

[Darkspirit]

Debian Testing, GTX 1060
Contrary to non-WR, scrolling is buttery smooth with WebRender.
The issue with vertical lines in content and on chrome (comment 1) is fixed.