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medicalart
01-09-2008, 08:36 PM
I've set-up bones and IK chain on a snake-like tube. (see photo) I've got 9 controller nulls. How do I "lock" the tip of the tube so it doesn't shift position when I move the rest of the chain? I've tried "fix" on the IK controller for the last bone. The bone is then fixed, but the corresponding position on the tube is not. It still moves. I don't have any weight maps applied.

Eventually I want to parent the tip to a null and then move the null around while the rest of the tube undulates. (At the moment a parent null for the object is at the other end of the chain.)

Suggestions greatly appreciated.

SplineGod
01-10-2008, 04:46 AM
IK Boost doesnt require additional nulls.
Not sure why your mesh is doing that.
If you want to want to move the object along a path Id
use either the PLG spline IK tool (check flay.com) or something like
DStorms free Trailer plugin (also check flay).

medicalart
01-10-2008, 08:01 AM
I've added the nulls so I can undulate the tube. Imagine attaching a rope to a doorknob. The free end can whip the rope up and down while it stays attached at the knob. Nulls along the way seem to give more control.

Larry, I'm re-watching your rigging DVD trying to find a solution to this!

I need a lot of bones to keep the motion smooth. I've used trailer plug-in, but it introduces other problems. I no longer need the tube to move along a path. (I've posted elsewhere trying to do that )

medicalart
01-10-2008, 10:00 AM
Any suggestions for how to get the loop to grow in this picture? The right side needs to stay fixed. The left side gets smaller as it feeds the loop.

adamredwoods
01-10-2008, 01:18 PM
I know what your DNA/RNA is doing... we had to do this also. :)

You actually have a difficult task. We used maya, and I think the animator animated it by hand, bone by bone.

Here's a quick test I did, probably isn't what you want. you want the small loop to always be there. The "apex"?? bone of your loop changes as it gets larger. that's a tough act.

The example I did was using striaght IK. I set the end goal strength to 30. I set another goal (the ball) to 1. I also put a slight bend in the bones rest rotation so it would bend in the direction i wanted.

Without Bones:
CurveConform Deformation plugin? That's worth a try.

Another suggestion would be the SplineDeformation modifier on your mesh, and then select the SplineControl tool. (But there's no undo, so be wise)



You may have to cheat. Can you cut the shot up into different angles, then cross-fade the shot together?

medicalart
01-10-2008, 02:58 PM
Thanks AdamRW. You mentioned a couple of things I have yet to try.

SplineGod
01-10-2008, 03:10 PM
I've added the nulls so I can undulate the tube. Imagine attaching a rope to a doorknob. The free end can whip the rope up and down while it stays attached at the knob. Nulls along the way seem to give more control.

Larry, I'm re-watching your rigging DVD trying to find a solution to this!

I need a lot of bones to keep the motion smooth. I've used trailer plug-in, but it introduces other problems. I no longer need the tube to move along a path. (I've posted elsewhere trying to do that )

As I said earlier it sounds like the PLG curve bone plugin is what youre looking for.
http://homepage2.nifty.com/nif-hp/index2_english.htm
Also Relativity has a utility called Dr Snake Maker which will create a chain of bones with nulls that will follow a path.

Does your bone chain need to form that loop or is that something different?

adamredwoods
01-10-2008, 05:21 PM
Just playing around with CurveConform Displacement modifier returned some good results.

I drew a curve in modeler, saved it, and selected that with the modifier. Turn on WORLD COORDINATES.

Then, when I move my object around, it becomes deformed based on it's relation to the curve's position.

You can also animate the curve's size in order to make the loop bigger or smaller.

lots to play with, interesting results.

medicalart
01-10-2008, 06:07 PM
As I said earlier it sounds like the PLG curve bone plugin is what youre looking for.
http://homepage2.nifty.com/nif-hp/index2_english.htm
Also Relativity has a utility called Dr Snake Maker which will create a chain of bones with nulls that will follow a path.

Does your bone chain need to form that loop or is that something different?


Larry, Yes, the bone chain ideally will need to form a loop. I may do some object replacements. Still looking at my options. Unfortunately, I can't figure out how to use PLG curve. (Instructions too confusing for me at this hour.)

At this point, I'd be happy just to lock down that last bone so the object doesn't move. May just try a new rig...

medicalart
01-10-2008, 06:10 PM
Just playing around with CurveConform Displacement modifier returned some good results.


I'll give that a try. Was reading the brief description in LW manual. Thanks for encouragement!

medicalart
01-10-2008, 08:37 PM
Curve conform adjusts the shape of the tube at frame 0, but I see no way to change the shape after that. It would be nice to morph the first curve to a second curve and use curve conform on top of that.

Morph target doesn't seem to work with curves.

Do bones work on curves? I tried but nothing happens.

I'm afraid curve conform is a dead end...

adamredwoods
01-11-2008, 09:21 PM
If you set the World Coordinates on the modifier, then if you physically move the object, it will act like an offset. I guess you could move the curve too and get the same results.