Hi there peeps;

This is probably a question that belies my immaturity with DOPS, but: I have a deforming object which I would like to suspend from a string. Think of, say, suspending a wind-up-toy from a bit of thread. I need to simulate the string itself (which I think I can use the swank new Vellum stuff to do!), but the object needs to contribute some notion of shifting center-of-mass, so that it sort of wiggles around as you might expect.

I'm not entirely sure how to set something like this up…would anyone be able to offer me some clues or possibly point me to some examples I might explore to learn more about how to approach this?

Many thanks!

Working to isolate the various problems I'm asking about and to simplify things, one of the sub-problems I need to solve is creating a dynamics object that has a changing center of mass. As a very, very simple case, consider the attached image. If this were to fall straight down, intuitively we would expect it to roll to screen-right. But it doesn't…it simply just falls straight down, as if it were solid and uniform.

How can I encourage Houdini to recognize the mass of the internal structure? From there, I *should* be able to animate that internal half-tube (rotating it inside the outer shell), and have it “wobble” while sitting on a ground plane, yes?

this is a super late reply but have you looked into constraint networks?

http://www.tokeru.com/cgwiki/index.php?title=ConstraintNetworks [www.tokeru.com]