Rigging bones for chain behavior - Polyloop

DaveH · 10th January 2008, 03:04

When I was first experimenting with bones I stumbled on a configuration that made the bone chain behave like an actual chain. The endpoints would remain anchored (probably as IK modifiers pointing to locators) and I could drag one bone around and have the other, non-anchored bones follow until the chain segment became taut.

However, since that wasn't the effect I was going for I neglected to write down the configuration and merely considered it an amusing accident. Now I want to use that kind of rig, but I can't remember what I did.

I've tried numerous times to recreate this, but to no avail.

Has anyone else built this kind of a rig, and if so, do you remember how you did it?

I did it using 5.1 Pro.

Thanks!

medeamajic · 11th January 2008, 23:32

If you mean the feet were anchored I imagine you used IK target helpers.

DaveH · 12th January 2008, 04:34

Sure, but that's not the part I'm having trouble recreating. The mystery is how to get the chain link behavior between the anchored endpoints.

And there were no feet; no legs, body, etc. This is a chain.

medeamajic · 12th January 2008, 07:39

You don't need feet and legs in order to use the IK target helpers to anchor the bones. I was trying to get your idea of anchored. What do you mean by anchored?

Your very vague in your post. Are you saing that you have a 4 bone rig and one end is fixed to the ground. Then you can pull the bone farthest away and it will straighten out or get slack depending on how you pull it?

DaveH · 12th January 2008, 17:09

In the original post I described the result as behaving like an "actual chain". By "actual chain" I meant something you'd buy at a hardware store. Metal or plastic, doesn't matter, with links and all that.

Here's a description of the effect I want:
Say you buy a 5 foot chain at a hardware store and pin each end to the ground, but only 3 feet apart; there will be slack in the chain. You can then grab any link and drag it along the ground until you run out of slack and the chain becomes taut. Inertia keeps any segment from moving until it's forced to, which happens when the slack between it and the link being pulled is gone.

Traditional/simple IK has you grab the end of the bone chain and the segments in the chain follow. (We all know that, I'm just setting up a comparison.) What I want is to be able to grab any bone in the chain, not just the endpoint, then pull that bone in some direction, and have all the other segments follow until the chain becomes taut.

I don't remember if there were anchors. I don't think I needed any, because I'm pretty sure I had IK set up between the endpoint bones; that would keep the ends anchored. I can't remember what I did with the bones between. Probably at least gave them unlimited ball joint modifiers. I did something to constrain the distance between them. But, as I say, experiments trying to recreate that haven't been successful.

rickei · 13th January 2008, 04:34

I don't do any animation, but I hate to see you struggle with this and not get a lot of answers.
so here is the only suggestion, that my pea size brain can think of right now..have you tried using directional force to resemble gravity?

really wish I could help

I don't guess you can speak French?

DaveH · 13th January 2008, 05:20

Well, your "pea-sized brain" managed to come up with a suggestion, which is certainly appreciated.

No, I don't speak French.

Gravity isn't going to solve my issue, unfortunately. What I'm really trying to do is come up with something that's like Maya's spine IK but runs in Carrara. Regular IK keeps "popping" and behaving inconsistently.

bwtr · 13th January 2008, 05:37

Could the Modifier>Behaviour>Track be of some interest maybe?

medeamajic · 13th January 2008, 12:16

IK will not keep things anchored! Target helpers will. You can set IK to anchor some points. Remember my post about the feet being stuck to the floor (anchored) but you can grab the crotch or thigh or middle of the chain in your case? Send me your email and I can send you a file that might be what you want. There could indeed be more than one solution to your problem.

Did you just have the skeleton or a mesh figure? With actual chain link you could do it through a hiearchy (no bones constraints with IK only).

DaveH · 14th January 2008, 14:49

bwtr said: Could the Modifier>Behaviour>Track be of some interest maybe?

I looked at that after you mentioned it, but I'm not sure how it would get the effect. Another way of looking at this is that I'd like to constrain the distance between bones but without having the IK interaction behavior on it.

medeamajic said: IK will not keep things anchored! Target helpers will.

The effect I remember having was the IK endpoints set the position of the chain, just like with normal IK, but instead of the other joints being driven by "normal" IK calculations, I was able to drag them around.

medeamajic said: Send me your email and I can send you a file that might be what you want. There could indeed be more than one solution to your problem.

Email sent via PM.

medeamajic said: Did you just have the skeleton or a mesh figure? With actual chain link you could do it through a hierarchy (no bones constraints with IK only)

The reason I'm looking for chain behavior on bones only is because there is a tube mesh surrounding the bones. The visual effect I want is sort of like a tube with a chain inside.

EDIT: I attached a sample file

medeamajic · 16th January 2008, 18:35

I see the attachment. I will ty to put something together in Carrara 5 soon (friday).

medeamajic · 20th January 2008, 00:49

DaveH,

I did not have much time to try rigging the chain. This is a real quick IK with a targe helper. You can grab the target helper and it acts like a chain. I think there may be way to start new bones like making a hip or an arm in order to make it act like a full chain (several short links with target helpers). I will try more later.

marko · 22nd January 2008, 18:36

I'm having a similiar problem I thought you may be able to help. I can't seem to figure out how to get my rig to bend at the knees as opposed to going thru the floor.

marko · 22nd January 2008, 18:40

I can't get the .jpg to upload. Its a cartoon character rig. I select the foot IK then go under Modifiers and select the go under Inverse Kinematics click on the Select Button and choose the floor.

I'm missing something here!

DaveH · 22nd January 2008, 20:47

That sounds like something that could use it's own thread since you're not trying to do something similar to what this thread's about.

It'll be easier to keep the discussions for each topic straight (questions and answers) if they're not mixed together.

medeamajic · 23rd January 2008, 01:10

marko,

I am actually giving you help in another forum on this.

DaveH,

The only thing I can think of is to break it down into several IK target helpes. Your old rmethod may have been better.

DaveH · 24th January 2008, 05:08

> Your old method may have been better.

Well, that's both reassuring and disheartening. Reassuring because it seems I was on a decent path, disheartening that a better solution wasn't obvious to someone with more experience.

Thanks for looking at this!

feyed · 26th January 2008, 03:28

you are over thinking it.

start in a blank file
use the bone tool on the top of the screen.
start on one side of the grid and click going across the grid for as many "links" as you want to have.

then select the fist bone click the bone tool and left and then click on the last bone you now have a very straight ik chain. with and ik target at the end.

you can with the normal move tool grab any bone "aka link" and drag it around. It's not exactly like a physical chain but it is very close.

the attachment is kind of an extreme example but you will get the idea

DaveH · 1st February 2008, 02:09

Your file won't read into my copy of Carrara, so I'm gussing you're using version 6. I tried following the instructions as best as I could, but that didn't work, either.

Using these instructions: "then select the fist bone click the bone tool and left and then click on the last bone":

1) "then select the fist bone" -> Ok, I selected the first bone I created
2) "click the bone tool" -> Ok, I clicked the bone tool
3) "and left" -> not sure what this means
4) "and then click on the last bone" -> Ok, I clicked the last bone I created.

I'm guessing those steps work in version 6.

But as I mentioned in the first post, I'm on 5.1 pro.

feyed · 2nd February 2008, 03:19

apologizes, I just tried my own directions in 5.1 and it didn't work

I know the bones were over hauled in 6 but I didn't realize it was that different.

Sorry I'm not much help either, but just to clarify the they should have read something like this.

1) "then select the fist bone" -> Ok, I selected the first bone I created
2) "click the bone tool on the left" -> Ok, I clicked the bone tool
~~3) "and left" -> not sure what this means~~
4) "and then click on the last bone" -> Ok, I clicked the last bone I created.

the steps are the same they just give different results in 6

I really should proof read thing better

10th January 2008, 03:04	#1 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	Rigging bones for chain behavior When I was first experimenting with bones I stumbled on a configuration that made the bone chain behave like an actual chain. The endpoints would remain anchored (probably as IK modifiers pointing to locators) and I could drag one bone around and have the other, non-anchored bones follow until the chain segment became taut. However, since that wasn't the effect I was going for I neglected to write down the configuration and merely considered it an amusing accident. Now I want to use that kind of rig, but I can't remember what I did. I've tried numerous times to recreate this, but to no avail. Has anyone else built this kind of a rig, and if so, do you remember how you did it? I did it using 5.1 Pro. Thanks!

13th January 2008, 12:16	#9 (permalink)
medeamajic Now, I learn animation Join Date: Sep 2005 Posts: 1,026	IK will not keep things anchored! Target helpers will. You can set IK to anchor some points. Remember my post about the feet being stuck to the floor (anchored) but you can grab the crotch or thigh or middle of the chain in your case? Send me your email and I can send you a file that might be what you want. There could indeed be more than one solution to your problem. Did you just have the skeleton or a mesh figure? With actual chain link you could do it through a hiearchy (no bones constraints with IK only). Last edited by medeamajic; 13th January 2008 at 18:38.

22nd January 2008, 18:36	#13 (permalink)
marko Vertex Join Date: Nov 2007 Posts: 4	Hello I'm having a similiar problem I thought you may be able to help. I can't seem to figure out how to get my rig to bend at the knees as opposed to going thru the floor.

23rd January 2008, 01:10	#16 (permalink)
medeamajic Now, I learn animation Join Date: Sep 2005 Posts: 1,026	marko, I am actually giving you help in another forum on this. DaveH, The only thing I can think of is to break it down into several IK target helpes. Your old rmethod may have been better. Last edited by medeamajic; 24th January 2008 at 05:44.

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11th January 2008, 23:32	#2 (permalink)
medeamajic Now, I learn animation Join Date: Sep 2005 Posts: 1,026	If you mean the feet were anchored I imagine you used IK target helpers.

12th January 2008, 04:34	#3 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	Sure, but that's not the part I'm having trouble recreating. The mystery is how to get the chain link behavior between the anchored endpoints. And there were no feet; no legs, body, etc. This is a chain.

12th January 2008, 07:39	#4 (permalink)
medeamajic Now, I learn animation Join Date: Sep 2005 Posts: 1,026	You don't need feet and legs in order to use the IK target helpers to anchor the bones. I was trying to get your idea of anchored. What do you mean by anchored? Your very vague in your post. Are you saing that you have a 4 bone rig and one end is fixed to the ground. Then you can pull the bone farthest away and it will straighten out or get slack depending on how you pull it?

12th January 2008, 17:09	#5 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	In the original post I described the result as behaving like an "actual chain". By "actual chain" I meant something you'd buy at a hardware store. Metal or plastic, doesn't matter, with links and all that. Here's a description of the effect I want: Say you buy a 5 foot chain at a hardware store and pin each end to the ground, but only 3 feet apart; there will be slack in the chain. You can then grab any link and drag it along the ground until you run out of slack and the chain becomes taut. Inertia keeps any segment from moving until it's forced to, which happens when the slack between it and the link being pulled is gone. Traditional/simple IK has you grab the end of the bone chain and the segments in the chain follow. (We all know that, I'm just setting up a comparison.) What I want is to be able to grab any bone in the chain, not just the endpoint, then pull that bone in some direction, and have all the other segments follow until the chain becomes taut. I don't remember if there were anchors. I don't think I needed any, because I'm pretty sure I had IK set up between the endpoint bones; that would keep the ends anchored. I can't remember what I did with the bones between. Probably at least gave them unlimited ball joint modifiers. I did something to constrain the distance between them. But, as I say, experiments trying to recreate that haven't been successful.

13th January 2008, 04:34	#6 (permalink)
rickei Respect the Dawg! Join Date: Dec 2005 Location: USA - Conway, South Carolina Posts: 784	I don't do any animation, but I hate to see you struggle with this and not get a lot of answers. so here is the only suggestion, that my pea size brain can think of right now..have you tried using directional force to resemble gravity? really wish I could help I don't guess you can speak French?

13th January 2008, 05:20	#7 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	Well, your "pea-sized brain" managed to come up with a suggestion, which is certainly appreciated. No, I don't speak French. Gravity isn't going to solve my issue, unfortunately. What I'm really trying to do is come up with something that's like Maya's spine IK but runs in Carrara. Regular IK keeps "popping" and behaving inconsistently.

13th January 2008, 05:37	#8 (permalink)
bwtr Brian Join Date: Jul 2005 Location: South Australia Posts: 2,086	Could the Modifier>Behaviour>Track be of some interest maybe?

16th January 2008, 18:35	#11 (permalink)
medeamajic Now, I learn animation Join Date: Sep 2005 Posts: 1,026	I see the attachment. I will ty to put something together in Carrara 5 soon (friday).

22nd January 2008, 18:40	#14 (permalink)
marko Vertex Join Date: Nov 2007 Posts: 4	I can't get the .jpg to upload. Its a cartoon character rig. I select the foot IK then go under Modifiers and select the go under Inverse Kinematics click on the Select Button and choose the floor. I'm missing something here!

22nd January 2008, 20:47	#15 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	That sounds like something that could use it's own thread since you're not trying to do something similar to what this thread's about. It'll be easier to keep the discussions for each topic straight (questions and answers) if they're not mixed together.

24th January 2008, 05:08	#17 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	> Your old method may have been better. Well, that's both reassuring and disheartening. Reassuring because it seems I was on a decent path, disheartening that a better solution wasn't obvious to someone with more experience. Thanks for looking at this!

1st February 2008, 02:09	#19 (permalink)
DaveH Spline Join Date: Sep 2007 Posts: 44	Your file won't read into my copy of Carrara, so I'm gussing you're using version 6. I tried following the instructions as best as I could, but that didn't work, either. Using these instructions: "then select the fist bone click the bone tool and left and then click on the last bone": 1) "then select the fist bone" -> Ok, I selected the first bone I created 2) "click the bone tool" -> Ok, I clicked the bone tool 3) "and left" -> not sure what this means 4) "and then click on the last bone" -> Ok, I clicked the last bone I created. I'm guessing those steps work in version 6. But as I mentioned in the first post, I'm on 5.1 pro.

2nd February 2008, 03:19	#20 (permalink)
feyed Vertex Join Date: Dec 2006 Posts: 2	apologizes, I just tried my own directions in 5.1 and it didn't work I know the bones were over hauled in 6 but I didn't realize it was that different. Sorry I'm not much help either, but just to clarify the they should have read something like this. 1) "then select the fist bone" -> Ok, I selected the first bone I created 2) "click the bone tool on the left" -> Ok, I clicked the bone tool ~~3) "and left" -> not sure what this means~~ 4) "and then click on the last bone" -> Ok, I clicked the last bone I created. the steps are the same they just give different results in 6 I really should proof read thing better