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morgn
11-08-2004, 01:57 PM
any idea what the best way is to animate a rope?
bones? curve?
share your experiences!!
cheers,
morgn.

Vertizor
11-08-2004, 04:21 PM
Soft body dynamics.

wmendez
11-08-2004, 06:51 PM
Depends on what your rope will be doing? I know Kim Aldus has a rope script on his site, you can use the make tail command, springOp,Create chain from curve, and constraining bone chains to hair are other options.

morgn
11-09-2004, 09:45 AM
hmm,
interesting. ill check those out. there are a few scenes where rope is required, they are used as a prop in a few booby traps in a cartoon style animation.

Chris Buckley
11-09-2004, 02:15 PM
I've done it using bones, and it's difficult to tweak for cartoony action. You can try clusters, I've had luck with that...... rope's a tough one though......

cgJD
11-11-2004, 11:36 PM
I would have a go with cloth. Sounds mad but I managed to get a phone-cord looking ok (i'm going to write a tutorial at some point).

Basically (i can go through it in more detail if you think it might work for your scenario) i create a grid of size 1 x 200 ( or similar number). The points at either end of the grid are constrained to clusters (using cluster centres) - this allows the ends to be moved by you and the rope will follow. (you can add others in the middle if the rope needs to be controlled in more than 2 places.

The ClothOp is applied to the grid and appropriate parameters are chosen (can take a bit of tweaking). To make it behave as though it has size make sure any obstacles have the 'push' distance set above 0 - say 0.5 or 1 should do.

Test the cloth to ensure it moves ok - best to keep tweaking it at this stage when the geometry is quite simple.

Next step is to attach nulls to each point (there is a script in the netview for this). You want to make sure that the nulls follow the points.

Then you have a chain of nulls that can deform some geometry - i.e a textured solid rope object (just use a cylinder and make sure the cloth starts in a simple outstretched position). You can animate it into the position(s) you need and let it settle for a number of frames.

Hope that gives you some ideas of one way to do it. It all depends on what you want it to do and how realistically you want it to behave.

Any questions - let me know

----------------------
JD
CG Job Hunter
http://www.jonathandavies.co.uk
----------------------

morgn
11-12-2004, 05:54 PM
wow, thanks. will try the cloth out..

cgJD
11-17-2004, 07:34 PM
I rendered a shot of the animated phone cord I produced using xsi cloth (using the technique I described above) to give you an idea of the results.

Obviously the cloth settings can be tweaked to behave more like rope rather than a springy wire.

Also if anyone has any criticism on the motion of the wire - that would be great.

I am also trying to get the wire to curl up as it relaxes like a normal curly wire does - I have used an expression linking the number of curls of the spiral to the distance between the handset and the phone body.

http://www.jonathandavies.co.uk/images/phone_cord/phone_cord_still.jpg (http://www.jonathandavies.co.uk/movies/phone_demo_divx.avi)

Click the image for the movie (DivX Avi - 1.9meg)

Ablefish
11-18-2004, 07:34 AM
With the phone anim, did you experiment with using the cloth sim as a cage deformer, or something other than a chain?

The main problem with the chain is the rapid twisting you get when the phone lifts up and sets down. Maybe an up-vector constraint to keep the phone card from flipping?

cgJD
11-18-2004, 06:32 PM
The twisting is caused by my expression on the number of twists of the cord. It gives it a more realistic look when outstretched (mimicing the way a curly wire stretches) but looks horrid when the handset and phone body get closer together. I might have to put a limit in the expression for when they get within a certain distance to stop that twisting.

I'll have a go with the cage deformer method. The main problem I found with the chain (the cloth just being a single 1 x 200+ grid) is the coils don't deform properly in extreme circumstances - e/g when they are bent through large angles. It does however give it an old mangled phone cord look :).

Does the motion look ok? - does it look as though it behaves like a phone cord? Cloth needs a lot of tweaking to avoid a very floaty behaviour.

Cheers for the feedback

Ablefish
11-18-2004, 07:00 PM
I thought the motion looked pretty good - other than the twisting. Looked great when you pulled the receiver.

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