Re: [css3-animations] Complex animations

On Tue, Mar 29, 2011 at 12:13 PM, Robert O'Callahan <>wrote:

> On Wed, Mar 30, 2011 at 6:30 AM, Rik Cabanier <> wrote:
>> The second part of your problem is a little different. In order to do
>> that, you need to have a precise timing event so you can determine if your
>> character is colliding with something else.
>> Mozilla's proposal could be part of the solution:
>> This proposal lets you call a JS function at precise intervals much like
>> Flash's onEnterFrame function. If you combine this with my request to pause
>> all animations on the page, you would know the precise state of everything
>> in the DOM.
> I think requestAnimationFrame is tremendously useful (I helped design it)
> but it can't be a complete solution since when animations are carried out
> off the HTML5 event loop thread (which you want for smoothness), JS may not
> be able to run at the moment the animation finishes.

This is why being able to pause all animations is important.
I don't think that this will give many issues with smoothness as long as you
use animations for the bulk of the motion and keep you JavaScript to a
The Flash player pauses all rendering during its ActionScript phase and real
world performance of games and animations is fine.

> SMIL animations can easily express what you need to express here. Perhaps
> we don't need to make CSS animations cover this use case.

I have to admit that I'm not that familiar with SMIL. I just glanced at the
spec and it seems overly complicated. Maybe it's better to extend the CSS
animation spec to allow for true keyframe animation.


Received on Tuesday, 29 March 2011 21:25:41 UTC