Ik spline handle , spine stretching issues

#1

so I have a joint chain for a spine set up with an ik handle and three controls to drag the clusters controling the spline.

ive got a simple strech system set up,
where ive created a curve info node using the arclen -ch1; command.

in this case arclen is 141.789.

I create a Multiply divide node,choose divide and
connect the arclen to input1X in a multiply divide node.

I put in ive 141.789 into input2x and connect outputX
from the multiplydivide node to each joint in the chain.

here is the problem
as seen in picture 2 and three the end joint where the joint chain ends
goes crazy and extends beyond its position if i pull the curve too much
is there a way to solve this?

if anyones interested in helping me, or know a better/smarter/more efficient way to do it please let me know! And want to see the file itself ill gladly email it to you

http://s21.postimage.org/ng29sk0fr/Capture1.png
http://s21.postimage.org/6gtbdap87/Capture2.png
http://s21.postimage.org/sh9ntx7w7/Capture3.png

#2

I think it’s the downside of using spline IK. The spline ik tends to overstretch itself. I believe it has something to do with the calculation of the arclenght and the round off of the numbers. I could be wrong though :). You should google ribbon spine. It’s a really good alternative to using spline IK for the spine and it’s used a lot in rigging characters.

It’s probably not the answer you were looking for but I hope it helps you anyway.

good luck with the project

#3

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