Some months ago I asked a similar question about the drawing of curves in real
time, and someone pointed me to an example at carto.net that also animated the
dash-offset. I was trying to do something like this:
http://srufaculty.sru.edu/david.dailey/svg/followpath13.svg
at the time (ultimately trying to simulate the pseudo-random growth of trees). I
don't remember the thinking at the time, but I remember working with a clip-path
to do part of it and running into some problems. I recall that Erik D. suggested
using a mask instead of a clip-path and that worked fairly well, so you may want
to keep masks in mind as an alternative to clip-paths.

I also recall that IE and Opera differ in terms of their animation of dash-array
-- Opera, as I recall, agrees with the spec and doesn't allow negative numbers
for the startOffset of a dash-array. See
http://srufaculty.sru.edu/david.dailey/svg/SVGOpen2008/textPath1.svg and
http://srufaculty.sru.edu/david.dailey/svg/newstuff/textpath1.svg for
comparison.

With just circles, Francis' suggestion of animating a clipPath seems quite
doable, and not as kludgy as you might think:

I would probably use an arc inside the clipPath and animate the angle (through
SMIL) so that the arc extends gradually from 0 to 360 degrees, unveiling the
circle as it goes.

In the case of bezier curves, it's a bit trickier, I think.

cheers
David





----- Original Message -----
From: cwflamont
To: svg-developers@yahoogroups.com
Sent: Wednesday, July 08, 2009 12:15 PM
Subject: [svg-developers] Re: circular animation





Thanks, Francis. I will study your script. It will provide enlightenment as I
have not used clipping paths before.

However, as I said, in this instance I am looking for a solution using
declarative animation rather than scripting. It seems to me to be such a simple
and obvious thing to want to do (animating the drawing of a circle), that it
must surely be possible to do it with SMIL in a more straightforward way than my
cludge?





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