Re: [csswg-drafts] [svg-2][css-transitions] Can we fix arc interpolation? (#10195)

First, that video is *incredible*. The web platform rules.

I'm not sure about web-compat, but worst case we can trigger this some other way.

But yeah, I don't see a reason why arcs *couldn't* be animated by their features, and it would give a better result in any situation I can imagine. Even with complex paths that happen to include an arc - they'll have to animate arc-to-arc anyway, and you almost certainly want the smoother, more reasonable behavior of feature-animation rather than control point-animation (+ discrete flag flips).

Specifically, the features would be :
* center, as a 2d position
* radiuses, as lengths
* radius rotation, as angle
* swept angle, as angle

The only cases I can immediately imagine being a little weird are if you're changing *only* the flags, because in either case changing a flag also reverses the angle of the end point relative to the start point, so it'll cause the arc to shrink to zero partway thru the animation. If you wanted to invert a pie wedge to the complement, which you can do just by flipping the size flag, to get a *good* animation (aka the wedge just spinning around the center and growing/shrinking to the new size) you'd also want to invert the start/end point, so it kinda rotates into the new position (rather than the endpoint just sweeping 360deg around). But I think that's the necessary behavior, and you might very well want the "shrink to zero" in some cases.

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Received on Wednesday, 10 April 2024 17:36:39 UTC