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View Full Version : Bones/IK with 2 Fixed Ends (Cable/Wire Simulation)

trankillity
09-14-2003, 06:17 AM
I have a problem which I've been trying to solve for about a week and a half now and it's really beginning to bug me now.

My problem is this, I have a skeleton rigged up with bones and this skeleton has cables protruding from it's head which go down to a backpack at the base of it's spine. The cables are fixed at the head end and are free-standing at the backpack. (http://bawx.mine.nu/lab4/ for demonstration)

After applying spline IK with Point On Curve deformers bound to a certain percentage of rotation of the head node, I am able to get the effect of a cable bending with relation to the head and looking reasonably realistic.

The problem now lies in the fact that the final bone in the chain flys out of position whenever the head node is moved. (http://bawx.mine.nu/maya.jpg for demonstration)

I have tried using point constraints and whatnot in order to get the final bone to stay in place and this works... but only to a degree. Binding the bone to a point allowed it to stretch dynamically but when pushed back the other way it didn't shrink dynamically.

I also thought that a wire deformer might work if I was to bind both the ends to point constraints yet I'm not exactly sure how to use wire deformers yet.

I am hoping that SOMEONE out there will read this and know exactly what I'm talking about and how to solve it because I've been asking in the various related IRC channels for about the same amount of time to no avail.

Thanks in advance for any suggestions.
dmcgrath
09-14-2003, 09:03 PM
I can respect you for trying this with Bones. But a more simple solution might be to use extruded, Nurbs tubes. Then you could go for a bit more control, I think. You have a lot of tubes, so I'm not too sure how the realtime updates would be. My suggestion might make it a lot slower, if it dose, I apologize.

Try to look in here for other ideas and inspiration

http://www.learning-maya.com/dynamics.php

There are a couple of tutorials that might work for your situation, they are in the top section.

Keep us posted on what works for you.



-dan
trankillity
09-15-2003, 03:37 AM
Thanks for the comment dude. The tubes are actually extruded nurbs which the output was made to be poly's.

I realised where my big problem was and have solved it now. I originally had the pipes as children of the head geometry so I was getting double transformations which was all bad. Removed that parent-child relationship and got rid of the bone/IK and decided to go with a good old wire deformer instead. Works almost perfectly now.
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