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Re: [css3-2d-transforms] matrix animation

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Fri, 27 Mar 2009 11:14:58 +0100
To: www-style@w3.org
Message-Id: <200903271114.58841.Dr.O.Hoffmann@gmx.de>
Dean Jackson:
> I'm afraid I disagree. Our main goal is to make the most common case
> both simple to author and look good. 

Matrix animation with composition by the author and some decomposition
by the viewer will not be a common case, I guess. Most authors will not
be familiar with matrix calculations anyway and for the others it is still
more convenient simply to write down the complete set of intended
transformations and let the viewer do the job of matrix calculations.

> The way we have specified 
> transform animations meets this (I believe).
>
> A secondary goal is to give authors complete control. The current
> specification also meets this. An author can avoid decomposition if
> they want to (it requires more work, but if they are *that* determined
> to control every aspect of their animation then they probably have it
> all worked out already).

Well, then explain a simple approach for authors to specify an
animation (direct interpolation) between matrix A and matrix B 
with an accuracy better than one device pixel.
If you can do it with the current draft, then I'm almost convinced,
that at least nothing is missing, even if other things are available
twice.

And it does not solve the possible mathematical problem with the
inverse, just to believe, that it works ;o)
I had already similar discussions to fix such believes for
constrained transformations in SVGT1.2.

>
> I do not believe there are any extra "error" cases. It's nothing more
> than the very simple and obvious animations from scale(1) to
> scale(-1), or skew(89) to skew(91).
>
> Lastly, we chose this approach after authoring a lot of content. It's
> currently implemented in WebKit nightlies if you want to try it out.
>

Well, I scripted a lot of content too (concerning SVG and animation)
and my conclusions are different. And I know what I miss in SVG
for some years, therefore I cannot see the advantage to miss it in
CSS3 too - however maybe matrix animation can be added to the
SVG draft in a more useful way than in this CSS3 draft ;o)

Because I typically use Linux there is a problem with binaries and
WebKit, however there is Arora for Linux and meanwhile I managed
to run 528.16 (Safari 4 beta) in my SVG animation test suite -
what was pretty inconvenient, because I had to use another
operating system, wouldn't had been possible at the beginning of
this year at all. 
Concerning the test result: Still a lot to do for WebKit, but in the
average already better than Amaya or KSVG1 or Opera8.x ;o)
Looking at this CSS3 draft, maybe I understand, why several errors
in WebKit appear within SVG animation ;o)
Some others are still pretty surprising and funny ;o)

Is this CSS3 transformation and animation available already in
528.16 - if yes, which prefixes uses WebKit - if I switch on the
other operation system in the next weeks again for an hour or
two, maybe I'll have a try.

Olaf
Received on Friday, 27 March 2009 10:26:16 GMT

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