Spline IK with Cluster Controls

#1

Hello,
I am new in the world of rigging, and trying to learn step by step.
I couldn’t find a solution to my problem within the forums or nor in the google.
(CGTalk search system seems to be down, I even did search within google for CGTalk!)

I have encountered a strange problem last week, and I am having trouble to solve it.
I have a humanoid character with tentacle-like arms. In order to create the arms like tentacles, I used Spline IK with Clusters attached to controls vertex. It is working like charm! I mean, only the tentacle movements. The problem is, when I move the main controller that moves the rig, clusters doesn’t follow the rig setup, but the tentacle arms stands in the dummy pose. When I parent or constrain the cluster controls to the main controller, cluster controls follow the rig as it should be, in a horizontal line (as I wanted) but it effects the related joints like I shift-selected them. So, even cluster controls stand in the dummy position when I move the character, the arms move back and forth.

Here are the screenshots

Dummy

Translate without parenting

Translate with parenting

How can I solve this problem?
And is the Spline IK system for the tentacle arms a good way to do such things?

Thanks for your time,
Can

#2

simply put, u got double deformations in your rig :slight_smile:
you’re moving the hands by themselves with their parents, but then again moving them with the clusters.

at this point, the easiest fix for you might be just parenting the clusters where you want them in the hierarchy, and checking the ‘relative’ flag for them. (on the cluster node) that should do the trick and not move twice…
let us know if that didn’t solve it.

as for the spline IK, it’s fine, although with just a simple spline IK, one looses control over rotation along the axis of each joint. the thing is - try doing some animation tests with it. if you think it’s alright, it’s probably okay. (or let the animators play with it a bit. they will tell you better.) it’s all about what poses are you supposed to hit with your character, and that, you should know prior to starting rigging.

#3

Hey Petr, thanks for your help!
Now my rig is working properly

With the double deformation in mind, you also helped me to fix further issues with my rig studies
What a shame - I didn’t even realise it was a double deformation :slight_smile:

Thank you very much!

#4

no problem, happy to help. note that checking the ‘relative’ flag for the cluster isn’t the ultimate solution, but will do in most cases.

keep on rigging :slight_smile:

#5

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