1330627 - Jerky animation when animating perspective and transform at the same time

Status: NEW

(Core :: DOM: Animation, defect, P3)

Description

[GibboK]

Attachment: 2017-01-12 14-03-33.flv

User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36

Steps to reproduce:

- Open https://jsfiddle.net/gibbok/8fL3g5tf/



Actual results:

The code snippet use Web Animations API to animate two divs.
The first animate `perspective` value for a `div wrapper.
The second animate 'transform' for `div` content.
Both animations execute simultaneously.
The result is a jerky animation on
FF: 50.1.0
FF: 52.0a2 (2017-01-12) (32-bit)
On Chrome Version 55.0.2883.87 m both animation are fluid and have no issues.


Expected results:

The animation should be fluid as in Chrome version.

Comment 1

[Brian Birtles (:birtles)]

I don't see any particular jerkiness on my machine, but I wouldn't be surprised if there was some: we don't animate 'perspective' on the compositor so it's susceptible to main thread jank. (You can verify this in the animation inspector where you can see that the transform animation is running on the compositor and the perspective animation is not.)

Comment 2

[Brian Birtles (:birtles)]

I'm not really sure how feasible this is or how frequently it is used.

Comment 3

[Brian Birtles (:birtles)]

Oh, now I see the video and I guess this bug is more about synchronization between the perspective animation and transform animation. That suggests we add another heuristic to turn off transform animations when we have perspective animations running at the same time? Perhaps it would just be an extension of bug 1301305 to treat 'perspective' as a geometric property. Or perhaps limited to when perspective is being animated on an (inclusive) ancestor.

Comment 4

[Brian Birtles (:birtles)]

s/turn off transform animations/turn off async transform animations/

Comment 5

[Jonathan Watt [:jwatt]]

Mass bug change to replace various 'parity' whiteboard flags with the new canonical keywords. (See bug 1443764 comment 13.)