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animateTransform nad by-transformation

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Mon, 5 Apr 2010 17:58:24 +0100
To: www-svg@w3.org, vbs85@gmx.de
Message-Id: <201004051858.25310.Dr.O.Hoffmann@gmx.de>
Hello,

by-animations are defined (SMIL) to be equivalent to the related
values-animations.
No matter, about what it is and whether additive is noted or not, this means,

by="1" is equivalent to values="0;1" additive="sum".

Correspondingly for vectors and lists of numbers or colors, one just
has to know, what 0 means (the neutral element of addition), 
for colors this is for example #000 or black. Because this seemed
not to be obvious for some people, this was clarified in relation to SMIL3, 
but there is no conflict with earlier SMILs or SVG.

You don't have to care about animateTransform, animate, the detailed
meaning of the attribute or the phase of the moon or something like that ;o)
The author is only in trouble, if the animated attribute is not additive 
(for some attributes or properties this is not defined and by- and
to-animations are not applicable).

This means especially, that one should not use a by animation, if
one does not want to start with a scale of 0, one can for example
use values="1;2". This surprise occurs mainly, because the 
interpretation of the scale type of transform was not defined 
very elegant concerning animation (could have been more
elegant with an interpretation with as exponential scaling,
but is now far too late).

Olaf
Received on Monday, 5 April 2010 17:01:01 GMT

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