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Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073)

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sun, 2 Nov 2008 13:51:16 +0200
To: www-svg@w3.org
Message-Id: <200811021251.16931.Dr.O.Hoffmann@gmx.de>

Hi Cameron,

> Hopefully this satisfactorily re-resolves your LC comment.

Yes, of course.

> I guess I’m not convinced that these are useful use cases, but…

As in many cases, this can become helpful in relation with animation.
For example (This is often needed in physics, science and techniques
or to provide some sample for educational purposes. If differential
equations are expanded into a power series and approximated,
this results typically in such type of motion.) if one wants to 
show a (1D) harmonic oscillation, this is not even trivial with 
SMIL and SVG. For arbitrary starting conditions it is not trivial
to calculate propper keySplines, keyTimes, values (And I did it
with some number crunching and checked the result with a 
similar trick). If you  simply use an animateTransform of 
type rotate projecting one direction to zero, you have the exact 
solution without any calculation. Typically the result will only 
be a line or only something consisting of linecaps, if 
vector-effect non-scaling-stroke is used, but this is already 
sufficient for several purposes including the possibility to 
check an approximation with keySplines, keyTimes, values in a 
simple and reliable way.
Obviously this works too with other 1D-motions, if they are
available with such a projection.

Therefore these low dimensional applications are surely not obvious
and need some imagination and experience, but still have some 
functionality. This will not be used by many authors, but it extends
the usability of SVGT1.2 for some authors with more creative ideas
looking for simple solutions of sometimes not trivial problems ;o)

Received on Sunday, 2 November 2008 12:16:00 UTC

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