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Re: [css3-transforms] interpolation of transform lists

From: Dirk Schulze <dschulze@adobe.com>
Date: Thu, 26 Jul 2012 16:41:17 -0700
To: Dean Jackson <dino@apple.com>
CC: Simon Fraser <smfr@me.com>, "L. David Baron" <dbaron@dbaron.org>, Chris Marrin <cmarrin@apple.com>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <FCE4EF5B-BA5A-443A-B81F-2DD459A74747@adobe.com>

On Jul 26, 2012, at 4:23 PM, Dean Jackson wrote:

> On 27/07/2012, at 9:12 AM, Dirk Schulze <dschulze@adobe.com> wrote:
>>> This is what WebKit currently implements. I do not see any reason to make it more restrictive than that. If the two lists match item for item, then interpolate between each item separately. This includes perspective().
>> Ok, but for the example where both list have: 'perspective() matrix3d()' it means that we decompose matrices individually and interpolate them individually, which leads to less performance.
> Yeah. But I don't think it's a big deal.
Ok. Since WebKit and Gecko people agree on that, I'll edit the spec to interpolate these functions as well, but with transforming it to a matrix and decompose it before the actual interpolation process.

>>> I think the only thing we need to decide now is whether or not we should allow translateX() to match against translate(), and so on. Currently WebKit does not support this.
>> The current spec defines which values can be animated together and how to do it. translateX() is a derivative of the primitive  translate(). Therefore both can be animated together.
> Right, sorry. I should have worded that along the lines of WebKit's implementation, not what the spec currently says.
>>> Maybe rotate3d() <-> rotateX/Y/Z is controversial. I don't know.
>> We have a request from authors to do that. IMO it makes some sense if both are rotating around the same axis (like rotate3d(1,0,0,45deg) and rotateX(45deg) but not rotate3d(0,0,1) and rotateX(45deg)). But I don't think that it is implemented somewhere.
> I don't think we should add special cases like that. It's either in or out.
Then it I would still like to know if rotate3d() should be transformed to a matrix before decomposing and should it force the complete list to be transformed to one matrix first, or treated like matrix3d()? I assume it should be treated the same.

> BTW  - how are we going to handle the fact that browsers have unprefixed their implementations?
Well, that fact doesn't make adding specification easier.

> Dean

Received on Thursday, 26 July 2012 23:42:06 UTC

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