Re: Proposal: Motions along a path in CSS

On 2014/08/29 7:52, Tab Atkins Jr. wrote:
> Are we going to have the same escape-hatch as SVG for implementations
> to not exactly calculate path length, and allow authors to specify
> one, or do we consider that a legacy allowance for old implementations
> that's no longer needed?

It's not just an escape-hatch. It's also so you can do things like set 
the pathLength to 1 and then specify path offsets as fractions. I think 
this proposal covers this with percentages so we don't need pathLength 
for specifying fractions.

> What happens at the points where the gradient is discontinuous?  The
> answer isn't really visible for <animateMotion>, as you pass the
> discontinuity instantenously, but motion-position lets you sit exactly
> on it.

I think it should jump to the end of the discontinuity. This is 
consistent with what we do for timing functions. Web Animations already 
specifies this:

   "If distance indicates a point on the path that is coincidental with 
one or more orientation path commands, displacement is the point after 
all orientation path commands (this will be the start of the next 
drawing path command if there is one)."[1]

[1] 
http://dev.w3.org/fxtf/web-animations/#the-intermediate-animation-value-of-a-motion-path-animation-effect

Received on Thursday, 4 September 2014 04:27:31 UTC