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dhenion
01-08-2009, 04:56 PM
I need to make an animation of a long fish-like tail. I'd like to have the base of it controlled by joints so that I can hand animate the base and have control over how it flaps. However I'd like the rest of the tail to be a cloth object so its very fluid with nice secondary motion, etc.

Is there a way to do this?

Any help appreciated, thanks!

FluidEdge
01-08-2009, 08:45 PM
I'd have the whole tail as a cloth object and paint rigidity/mass weights to the base of the cloth, getting less and less rigid as you go down the tail then with a transform constraint on the base vertices and keyframe animate the position of the locators/constraints. The base of the cloth, being more rigid than the other end should move stiffly with the locators (you can set the strength of the constraints through paint or in the Attribute Editor) and the tail should flap about.

My 2 cents?

dhenion
01-08-2009, 09:06 PM
I'll have to match the very base of the CG tail to footage of a girl's hips shot on greenscreen - the tail is to turn her into a mermaid - so the base of the tail has to stay locked exactly to her hips (which I'll be 3D tracking.) Then I'll need a few bones a bit further down along the tail to animate the base 'flapping' of the tail.

I think what you posted is the right way to go - but I'm wondering if I can do weighted constraints on the cloth so the base of the cloth bends smoothly as the joints animate - basically doing a skin bind, but just doing it with vertex constraints on the nCloth to some bones. Does that make sense?

FluidEdge
01-08-2009, 09:19 PM
Tricky. It might be easier to do it the old fashioned way with a Soft Body and goals. I'll have another think and see if i can think of a better way!

I see what you mean about needing joints.

What about doing two versions of the tail, one completely stiff and one flapping about and then Blend Shape between them.

Or rig and animate the tail but add a bit of nCloth to the lower half - constrain the top ring of vertices of the cloth to the ring of vertices in about the middle of the tail if you see what i mean.

I'm thinking out loud!

It's a tricky one - good luck

tpalamar
01-09-2009, 07:38 PM
If you have to have bones in it, think of setting it up in reverse. Basically use hair curves or nCloth to drive the joints, which in turn are bound to your geometry. That way you can have seamless geometry but multiple influences on your rig.

Hair curves are a bit easier to setup than nCloth. You would use a spline IK handle and the spline would be a dynamic hair curve.

HowardM
01-10-2009, 05:29 PM
Duncan kindly posted a solution -

http://forums.cgsociety.org/showthread.php?f=86&t=703771

oops, read more carefully, maybe this wont exactly help you, but
its easier just animate the tail, make it cloth, use input mesh attract to make the cloth roughtly follow the tail, then you can have damp or less attract to give it secondary motion, even use weight maps...

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01-10-2009, 05:29 PM
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