Houdini Resources

Updated on June 26  2024


RBD | Bullet

Deborah R. Fowler



RBD | Bullet Collision Padding

Posted Feb 21  2021
Updated: Feb 21  2021


If you have not read the RBD basics page click here

Bullet solver is designed to be fast, inherent with that speed are assumptions. We already talked about the assumption that things are "shrink wrapped" or assumed to be convex hulls. This becomes obvious when you display your geometry proxies inside the dop (don't leave those on - it takes processing time). However - there is another thing to be aware of in the calculations that won't show visually and that is COLLISON PADDING.

Particularly if you are using proper scale you may feel the need to adjust this. I created this page when a student came to me with coins going crazy as they were dropped into a bowl so I thought I'd cover multiple ways to resolve this and the inherent jittering that sometimes can occur with the bullet solver. All of these solutions are easy - so still with BULLET!

So here is the problem as presented. The coins on the left are going bonkers. Yes when I plug in a primitive sphere, it works fine. That's what gave me the clue to look at the coin.



So how do we resolve this?
Other methods to stop the jittering are:

.