2023110 - Fix the transform in the quad cache key

Status: RESOLVED FIXED

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

Description

[Nicolas Silva [:nical]]

The quad cache key contains a spatial node uid that is not stable across frames, which is incorrect. In addition, it gets in the way of Glenn's work on invalidation. The plan is to switch it to the local-to-device transform's value itself.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 2023110 - Hoist some of the transform computation out of prepare_quad. r=gw

The motivations are:

• to have access to the local-to-device transform earlier in the call chain in order to use it for the cache key,
• to avoid per-primitive redundant computation that should be done per-cluster,
• (as a bonus) to reduce the number of parameters in a lot of the quad functions.

Comment 2

[Nicolas Silva [:nical]]

Attachment: Bug 2023110 - Use the local-to-device transform in the cache key. r=gw

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/0df3b854e315
https://hg.mozilla.org/integration/autoland/rev/1b828aff8d79
Hoist some of the transform computation out of prepare_quad. r=gw
https://github.com/mozilla-firefox/firefox/commit/2f5d18a49c7c
https://hg.mozilla.org/integration/autoland/rev/1b54d1353607
Use the local-to-device transform in the cache key. r=gw

Comment 4

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/1b828aff8d79
https://hg.mozilla.org/mozilla-central/rev/1b54d1353607

Comment 5

[Nicolas Silva [:nical]]

Attachment: Bug 2023110 - Hoist transform code out of prepare_quad and use the transform value in the cache key (beta version). r=gw

Comment 6

[Nicolas Silva [:nical]]

The uplift form on lando does not let me edit the usual blurb about rationale and risk. so here it goes:

Why is the uplift needed:

Visual regressions (For example bug 2025272).

Risk of taking the patch

Rather low, although I wish the fix was a little less invasive. The fix is simple though.
The patch just made it into nightly so we could wait for a few days before uplifting.

Affected branches

The bug was introduced in version 148, but was unnoticed until it was made easier to reproduce in version 150.
I think that uplifting to 150 should be enough.

Comment 7

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/76348491c23d
https://hg.mozilla.org/releases/mozilla-beta/rev/248656ace692