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snsmoore
12-31-2007, 05:22 PM
I'm working an a set of simple characters that I loosely modelled from a cheap bendable figurine I got at a toystore. (This is a hobby project that I'm doing to create some stories for kids in my kids church class.)

So far I've got several characters modelled and I have a rig that is working well on 1 of the characters, with the exception of the character's belt. When I bend the character as if he is picking something off the ground the back of the belt stretches a lot. I know the geometry is stretching more in the back and squishing in the front. What I'm wondering is how to compensate for the belt only. Is there an easy way to get around the stretching(i.e. separate objects, using some morph maps, etc.)?

:help:

-Shawn

(The 1st picture shows the belt stretching, the 2nd pic shows the character's rest position.)

ramccombe
12-31-2007, 06:41 PM
Looks like you need some weight maps, at a minimum I would say 2. 1 for the belt and 1 for the rest of the character. Apply only the body weight map to the bones. Don't apply the belt map to anything. I think that will work.

snsmoore
12-31-2007, 08:34 PM
Thanks for the suggestion....

Well with the weight map, now the belt doesn't deform, but it of course needs to rotate with the bending of the back.

Do I need to break my spine base bone into 2 bones one real small one that is the length of the belt and then have the belt map associated with that bone.

Here's what it does with the belt weight map unassociated and the torso weight map with 0% weighting on the belt.

Am I missing anything else?

-shawn

Surrealist.
12-31-2007, 08:42 PM
You can add small hold bones and parent those to the pelvis (or whatever bone you have set up to rotate the hips). Play with the rest length until you get an area of influence that just covers the belt width. Use as many as you need around the circumference of the waist to hold the belt together. These bones can also be key framed separately to compensate for any distortion you don't want.

UnCommonGrafx
01-01-2008, 06:32 AM
Maybe boning the belt while telling some of those bones in the back to follow the bones in the spline along the rotational channels needed. In this way, the bones of the belt would move the belt along the bend of the back without distortion.
I envision the bones in the back arranged vertically around the belt. Maybe even two rows to bend the belt in half.
Good job on doing and asking the question.

Giacomo99
01-01-2008, 07:32 AM
You can add small hold bones and parent those to the pelvis....Use as many as you need around the circumference of the waist to hold the belt together. These bones can also be key framed separately to compensate for any distortion you don't want.

If there are a large number of bones active the computer will update very sluggishly when the character is being posed. If one has a really powerful video card, this might not be a problem, but for most users it will be. It's simply not practical to use hold bones for the extensive fine-tuning of deformations that a well-rigged character will require.

Weight maps are probably the answer here--unfortunately, Lightwave's implementation of weight maps to manage deformations is pretty inadequate and the documentation is all but nonexistent. Good luck.

dwburman
01-01-2008, 10:18 AM
i don't know if this will work, but what if the belt is included in the body weight map with a setting of 25 or 50 percent instead 100 percent? That way it'd deform but not as much.

Surrealist.
01-01-2008, 11:04 AM
Another thing you could do with the hold bones is string them chained around the belt as one unit like a belt and the whole thing parented to the spine or pelvis. I have not tried this but I have used the other method I suggested with good result.

Good luck with it. Please let us know how you come out. :)

Surrealist.
01-01-2008, 11:10 AM
Also I thought this video (ftp://ftp.newtek.com/multimedia/movies/w3dw/button.mov) might give some ideas for an alternate approach.

snsmoore
01-01-2008, 10:14 PM
Well, I did some experimentation and the chain of bones around the belt idea is what I've got going on now. Basically I have 2 bones in the front for the belt, 2 in the back and one on each side. This keeps the belt well formed when the character bends. The buckle is deforming a bit, but I may just add 1 more hold bone in the front for it(leaving 3 hold bones instead of 2) I also had to limit the range of the bone to get this working, but basically I have a chain of bones going around the belt. I guess this simulates a circular bone(is there such a thing in the industry??)

Thanks for the ideas!

-shawn