Dynamic Constraint functionality or error?

[MMZ_TimeLord]

Okay folks, maybe someone can help me understand this better or show me what I'm missing.

 

What I want out of this is a chain that can be pulled taut as if pulling something. I also want it to appear like a chain when it's tension is released.

 

I have a chain of bones that I have the last one in the chain dynamically constrained to a null. This is VERY similar if not identical to the third "Tech Talk" tutorial on dynamic constraints by Bob Croucher.

 

Here's the rub. When I pull the null above the anchor (attached mov file) or try and straighten the null (as in the attached jpg) the chain starts to pull away from the null as if it's on a spring and not attached.

 

What gives? Did I not choose the correct constraint for what I want? or is something broke?

Broken001.mov

[serg2]

It is necessary to establish parameter "Targetting" in meaning "None".

Try it

http://www.bee-s.com/~gggg/tut/dc/dc.prj

and

http://www.bee-s.com/~gggg/tut/dc/dc4.prj

[MMZ_TimeLord]

Now I'm feeling stupid. Our properties on the dynamic constraints are identical. And I DID set the targeting to 'None'.

 

I'm at a loss as to what is different on our two projects. I have gone through every bone, null, action and model property and I can't seem to see anything different between your 'dc.prj' and my test project.

 

Anyone have a clue? (Mine was made with V12.0q)

 

This is the specific chain I'm having a problem with. You can see the null is currently selected.

After positioning the null, I held down the space bar to let the dynamic settle down. This is where it stopped.

 

Quite a long chain and it appears the longer the chain, the more fake mass it aquires and pulls it away from the null.

 

I have tried to turn down the mass (but it only helps a little).

I have tried to turn up the mass (but it only makes it slower, but does not extend the pulling away from the null).

I have tried to turn up the drag (less bouncy).

I have tried turning down the drag (more bouncy).

 

How can I fix this?

 

EDIT: Okay, I found the culprit. Gravity setting directly gets multiplied by each bone in the chain. In other words it makes no difference at all what your 'mass' is set to, it only affects how heavy the chain reacts not how far it pulls away from the null.

 

I set my gravity to -10 on the action and set my mass to 10 and set my drag to 5. This made the chain behave somewhat.

(see the movie attached.)

 

It still seems odd to me that the chain tries to pull away from the null. Should I try and add a 'translate to null' constraint and play with the enforcement?

 

Here's the project for anyone who want's to play with this. (Remove the '.txt' extention before opening)

Broken002.mov

DC_test.prj.txt

[bobcroucher]

Hi TimeLord,

 

Noel from Hash placed this on AM:Reports for you. There was a maximum number of solver iterations to be performed per chain before giving up in the interest of speed. With 27 bones, this number was exceeded, and needed to be increased. The limit now scales up with the number of bones in the chain. Serg's example had about half the bones, and it performed fine. Now yours does as well.

 

Bob

[MMZ_TimeLord]

Sweeeet... Now our drawbridge chains will function properly... wheee!!!

[serg2]

URRRAAAA!!!