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[css3-transforms] about ‘animate’ and 'animateTransform'

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Thu, 26 Apr 2012 17:43:03 +0100
To: www-style@w3.org, public-fx@w3.org
Message-Id: <201204261843.03940.Dr.O.Hoffmann@gmx.de>
Hello,

this is about:
http://www.w3.org/TR/2012/WD-css3-transforms-20120403/#svg-animate-element
http://www.w3.org/TR/2012/WD-css3-transforms-20120403/#svg-animateTransform-extension

The section 7.8.1. allows animation of the transform attribute/property with 
the SVG/SMIL elements animate and set.
As far as I understand this for animate the values list will look like this:
values="scale(3); translate(15 23); skewX(30) skewY(-30); perspective(17)"
right?

Obviously the values are strings.
Well, ok, because section 15 is referenced, it seems to be ok to interpolate 
with calcMode linear, spline, not just discrete animation, as the definition
of calcMode might implicate without these further explanations from 15, right?

But note that from-to, from-by and by animations are anyway equivalent
to specific values animations, therefore 15. should better explain
rules for animation values in general, not only for from-to,
because the equivalent-rule covers from-to already.
Without a general explanation obviously for values animations
the usual SMIL rules apply, this means here calcMode discrete
for strings. Due to the equivalent-rule then this applies for from-to as
well. But I think, this is not intended, therefore the text in 15 needs
to be more general to be applicable.

I just wanted to note, that currently 
http://www.w3.org/TR/SVG/animate.html#AnimationAttributesAndProperties
explictly notes which attributes are additive and cumulative, such strings
are not, even if only something like values="scale(3); scale(-3)" is noted.
This looks different from the same animation with animateTransform.
Is this intended? If not, there is some text required about additive
behaviour.

Another issue is, that currently 
http://www.w3.org/TR/SVG/animate.html#complexDistances
explains possible types for paced animation.
Obviously there is no paced animation between strings.
But for a few transform types this could be defined, some more
as currently for animateTransform possible - will this be added in
the future or will this remain excluded for animate animations of
transform?

However for animateTransform it seems to be simpler to allow
some more paced animations.
I think, SVG 1.1.1, section19.2.7
allows already paced animations for scalars like rotateX/Y/Z,
scaleX/Y/Z, translateX/Y/Z, perspective etc.
However, with some additional text this could be available as well
for scale3d and maybe translate3d - is it intended to add this?
Paced animations seems to be excluded for example for
matrix, matrix3d, rotate3d, because there seems to be no meaningful 
distance function resulting in a paced animation. 
For example rotate3d has similar problems as rotate with its three parameters,
but I think, the parameter values of translate3d can be adjusted in a way, 
that one can compute a distance, if all values are converted in user units 
before.


Olaf
Received on Thursday, 26 April 2012 16:43:39 GMT

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