Soddy Circles
Wednesday 7 May 2008 - Filed under Flash
We have a winner! At 4:05 a.m., I received the following from Ryan Phelan, who will get a free copy of Foundation ActionScript Animation 3.0: Making Things Move!
As you can see, a Soddy Circle is one of the two circles which are tangent to the other three tangent circles. The inner Soddy Circle is between the three, and the outer one surrounds the three if possible, or lies off to the side if necessary.
Ryan beat out Jason Fistner by about 21 minutes, and Anselm Bradford came in less than an hour later. All three were awesome and as far as I can tell are technically accurate and well coded. Ryan was just first. I’d show the rest, but a Soddy Circle is a Soddy Circle is a Soddy Circle. 
I think I might do a little contest like this on a regular basis, as long as my supply of books holds up.
2008-05-07 » keith
7 May 2008 @ 11:54 am
Great job Ryan, congrats.
@KP – Yes, please do more contests!
7 May 2008 @ 12:24 pm
blast!
oh well
i spent about 30 minutes trying to ignore the problem and get sleep haha
please no more challenges
my brain doesn’t let me let things go
7 May 2008 @ 12:26 pm
btw…
i’m able to get this one to error
ArgumentError: Error #2004: One of the parameters is invalid.
at flash.display::Graphics/drawRoundRect()
at flash.display::Graphics/drawCircle()
at soddy_circles_1_fla::MainTimeline/drawSoddyCircle()
at soddy_circles_1_fla::MainTimeline/drawSoddy()
at soddy_circles_1_fla::MainTimeline/draw()
at soddy_circles_1_fla::MainTimeline/onMove()
8 May 2008 @ 1:14 am
Hmm… I guess that’s what happens when you rush through some code at 2:00 am to try and win a book! Might just need a conditional around the call to drawSoddyCircle for the radius = NaN case?
8 May 2008 @ 12:49 pm
Great Job Ryan, congratulations.
Visually worderfull and very precise code
And thanks for the source: is an case study
saludos
13 May 2008 @ 5:24 am
Thank you for helping to become more intelligent but what a headache!
I didn’t understand the formula in the script and i found the
solution in wikipedia The radius of the 4th circles are given by
this formula: k4=k1+k2+k3(+or-)2*Math.sqrt(k1*k2+k2*k3+k1*k3) with k=1/R. Knowing the radius it is relatively easy to get the center.
Wiki says the formula was discovered by Descartes and rediscovered
by Soddy.
PS i have already your book.
13 December 2008 @ 11:48 pm
[...] when I thought about doing this fractal, I remembered a post a while back on Bit-101 about Soddy Circles, which are also circles tangent to 3 circles which are tangent to each other (both inner and [...]