# Rigid bodies not colliding

Hi everyone

Basically, i am making a chain for an animation (using the game engine then baking IPOs) but when i place an object under the chain (a pulley) the chain slowly passes through it. I temporarily fixed this by making the pulley a simple cylinder and using cylinder bounds. But now the chain links pass through each other and this is the result. They are constrained by ball joints, but is there any way i camn limit the rotation of the ball joint to stop this happening?

Thanks

You can with the “Generic” joint type (same place you selected “Ball”). The fields should be self-explanatory, and I think the joint works well, although it’s labeled as experimental.

Tried that but that seems to screw it up completely. links just disappear / appear randomly

In the chapter on rigid bodies in the physical simulation book in my sig there’s an in-depth example on how to get rigid bodies to work together when one is hollow and the other is inside the first, like in the case of a ball and a cup. You have to do some kind of tricky things with the collision boundaries. I’m not able to go into detail about it at the moment, because it’s a little bit complicated. I’m also not 100 percent sure off hand that it would be pertinent to your case.

I know this isn’t all that helpful, but if you’re interested in doing advanced rigid body work you might want to check out the book if you haven’t already.

Thanks for the reply bugman, that book was helpful on a few things. But boundry types have evolved alot since the writing of that, and it didn’t really go into doing objects with a hole right through them. im stuck so far =( unless i use a sort of symetrical chain where each link slots into the next instead of looping through…

Yeah, I haven’t had much chance to keep up with the latest developments in rigid bodies. But if you find what you’re looking for, please post it here, because I’d be interested to know how you solve this.