I'm trying to imitate the motion of rocks falling on dirt. Since the RBD Solver seems to give me more accurate and realistic looking results over the Bullet Solver, I decided to go with that method using RBD Fractured Object. When I first had my scene setup with Bullet, I was able to use a little VEX in the SOP Solve to artificially reduce velocities as rocks fell below a certain Y value. It seems like that setup isn't compatible with my RBD setup, so I was wondering what would I need to do to get it working? In addition, how can I write an expression that would tell the solver to reduce the velocities of the objects by half and double their weight each time they impact the ground? Any tips would be greatly appreciated. Thank you!