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animateTransform & matrix

From: Benjamin Himpel <bhimpel@yahoo.com>
Date: Sun, 19 Jan 2003 16:29:16 -0800 (PST)
Message-ID: <20030120002916.83555.qmail@web41402.mail.yahoo.com>
To: www-svg@w3.org

Hi,

Why can one not use animateTransform together with
matrix? Why does the specification not allow
expressions like the following?

<animateTransform attributeName="transform"
attributeType="XML"
type="matrix" from="1,0,0,1,0,0" to="2,3,1,2,1,1"
dur="5s"
additive="sum" fill="freeze"/>

One could simply define this to be the animation,
which follows the straight line between the two
transformation matrices with constant speed.

I found the following excerpt in some newsgroup, but
do not remember which:

"Because of mathematical issues, we couldn't allow
arbitrary matrics to be part of the animation values.
You can only animate primitive operations such as
rotate, scale or translate. But you can define
additive 'animateTransform' animations on the same
'transform' attribute in such a way that you can
achieve most arbitrary matrix effects.

Bottom line - you should be able to do just about
everything you can do with a matrix using some
combination of 'animateTransform' animations."

I do not understand, what mathematical issues would
relevant here. As matter of fact mathematicians would
not mind to simply specify the path (including its
parametrization) of transformation matrices instead of
the complicated and inefficient way of using
compositions of animations for primitive
transformations. Also it is much more difficult than
it seems, to find the _animated_ composition of
primitive transformation which is equal to a specified
path (including parametrization) of transformation
matrices.

Does anybody have an answer to or comments about any
of this?

Thanks,
Ben

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Received on Sunday, 19 January 2003 19:33:18 GMT

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