View Full Version : Tentacles

07 July 2007, 04:12 PM
Hi everyone, first off i hope that im not asking something that has been asked before. I did have a search and found a few topics but they all seemed to be a bit old and not exactly what i was looking for. Anyway

At the moment I am trying to create a rig for a tentacle type object. To get the general movement I wanted I just figured that i would use a spline IK and cluster the curve. The problem with this I have found is you get ok movement but it was hard to get enough control over the tip of the tectacle. Therefore I have thought of having spline IK for the main body of the tentacle and fk control of the joints at the tip for some extra articulation. Anyway my main problem is I now need to get this tentacle to wrap around an object and pick it up while still curled around it. I figure that I need to use a motion path and attatch my tentacle bones to this path to get it to wrap around. Therefore at the moment I have 3 bone chains and controls,

- 1 set are the actual deofmation bones the geometry gets skinned to,

-1 set is the IK spline and fk bit for the articlulation at the tip

- 1 chained where each bone is attatched to a motion path of a curve. Then i broke the time expression on the U value and created an expression of my own which means i only move the joint at the tip and the rest of the joints follow behind along the path.

I've then used nodes to create a blend control to blend the control between the spline IK and the chain along the motion path.

I still need to figure out how to keep i wraped up and still have it picked up. I guess ill have to create another set of controls a level above the IK spline ones or something.

I'm just wondering if anyone has any thoughts of a better way to do this. For one thing it takes a quite a while to setup, although im impriving this by creating scripts now. Also it seems to be overly conplicated but its the only way i can figure it out at the moment the hard bit is going to be animating the blend between controls as ill have to try and get the motion path curve into a position that will hopefully follow on from where the IK spline is. Anyway any ideas or points in the right direction would be great. Idealy id love something a bit like the tentacles in pirates of the caribean but I think i read somewhere that the rig for those are actually quite harcore. Who would have thought rigging an object that is basically a cylinder would be so hard!!!

07 July 2007, 04:43 AM
You've probably already finished the setup by now but I might as well just chime in here to give you an idea. I just finished a tentacle setup for a large squid creature (giant squid, like 50,000 leagues under the sea type squid heh) and this is the setup I used.

- 100 skinned joints attached to a splineIK setup.
- duplicate of splineCurve with waveDeformer attached to it, this curve gets blendshaped to the splineIK curve to allow for the blending of a procedurally generated `wave`effect.
- 5 splineIK offset controls tied to clusters positioned down the tentacle.
- 10 FK controls to allow the animator to pose the tentacle.
- End controller using cluster attached to last 2 vertices of splineIK curve that allows the animator to stretch the tentacle but also position the end of the tentacle and 'pin' it in place.
- wire deformer on splineIK curve to attach suction cups to the tentacle mesh itself.

The system itself is just a modified approach to the Schleiffer spine used for character rigging, FK controlling a splineIK by parenting the clusters to the FK joints. The animators working with it were very pleased and found it simple to generate the cycles and animation they needed :)

hope that helps some!


07 July 2007, 09:56 PM
I very much like that Shawn.;sounds very cool, whish I had some tentacles to do to try all that :).
Thanks for sharing.

07 July 2007, 02:55 PM
Hey BoostAbuse, thanks very much for the reply, its nice to hear a fresh approach to the problem. I havn't had a go at making the tentacles they way you have described yet but i think i can understand most of what you say and i'm familier with the jason schliefer spine setup you mentioned. I'll let you know how i go and if I have nay problems. Thanks again for the help :)

07 July 2007, 08:51 AM
- 5 splineIK offset controls tied to clusters positioned down the tentacle.
- 10 FK controls to allow the animator to pose the tentacle.

Just curious are you using seperate FK joint chain (bind it to splineIK curve) or you are using offset clusters to rotate them in FK fashion.

many thanks.


07 July 2007, 03:25 PM
I'm using a separate FK chain to give the animators the rotational capacity to move the tentacles in a more fluid form. The clusters I mentioned are simply parented to the FK chain and allow the animators to offset their curvature or slightly exaggerate the posing of the tentacle should they need it. Skinning the splineIK wouldn't really work for this setup as there's already a significant amount of deformations being transferred to the curve to get a wave effect and a cross-blending between procedural animation and keyed animation.


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