1617050 - Drop shadows are rendered incorrectly if content is partially clipped

Status: RESOLVED FIXED

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

Description

[Connor Brewster [:cbrewster]]

Attachment: test-case

If the original content is clipped for some reason, the drop-shadow for it is not rendered correctly.

Comment 1

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

The priority flag is not set for this bug.
:jbonisteel, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 2

[Jessie [:jbonisteel] pls NI]

Connor - do you think this is a regression? If so, can you find a regression window?

Comment 3

[Connor Brewster [:cbrewster]]

I don't believe this is a regression, I tested with WR from ~2 years ago and it has the same issue.

We probably need to do something along the lines of the todo here: https://searchfox.org/mozilla-central/rev/278046367dab878316f60f0bd7f740cf73f3c447/gfx/wr/webrender/src/picture.rs#4683-4684

Comment 4

[Rares Doghi, Desktop QA]

I managed to get a regression range on this issue but its not very accurate though since I got the Not enough data to bisect message.

Last Known GOOD:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=bf3951daded0b4fefd0fc81ee22ce5d536df2099&tochange=e92ff56d2be21676b447c6fbb87b4c4479539bc9

First Known BAD:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=57c4b2afc95bfb3c444c732802d99c8522414a1b&tochange=e92ff56d2be21676b447c6fbb87b4c4479539bc9

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Nical, do you have a feeling about how to fix this?

Comment 6

[Nicolas Silva [:nical]]

We probably need to do something along the lines of the todo here: https://searchfox.org/mozilla-central/rev/278046367dab878316f60f0bd7f740cf73f3c447/gfx/wr/webrender/src/picture.rs#4683-4684

I think that Connor's suggestion makes sense. The reason this was left as a TODO and not just fixed along with whatever the comment came with probably is that there was some trickiness involved but I don't remember very well. I'll have a look when we are confident with the work blocking shipping more intel GPUs.

Comment 7

[Nicolas Silva [:nical]]

Attachment: Bug 1617050 - Take shadow offsets into account when clipping a primitive. r=gw

Comment 8

[Nicolas Silva [:nical]]

Attachment: Bug 1617050 - Add a wrench reftest. r=gw

Depends on D68230

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/da4563936652
Take shadow offsets into account when clipping a primitive. r=gw

Comment 11

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/da4563936652