Hi there;

I'm trying to craft a simulation of a large number of elastic rubber bouncy balls down an incline (like that old Sony Bravia commercial in San Francisco), and am trying to explore the best simulation solution for this.

At the moment, I'm trying POP grains, but the result seems to lose energy quickly (it looks more like I'm dumping sand on the ground than a bunch of bouncy balls). I have "bounce" set to 1 everywhere I can find it (on my colliders and my POP object), but I'm unsure what further I could adjust to try to get the particles to appear to bounce down the hill, picking up energy as they go.

I also tried RBDs (replacing the particles with actual sphere geo), and the simulation looked much better, but I need to do a bit of artistic trickery to try to constrain the motion a bit, and am unsure how to do that in an RBD system. In POP grains, I can use a simple wrangle to try to shape velocities and so on, but am not sure how to do this with RBDs.

Anyway! Anyone have advice for things I might further explore?

Thanks!

dhemberg
In POP grains, I can use a simple wrangle to try to shape velocities and so on, but am not sure how to do this with RBDs.

RBDs can use POP nodes so there should be no issue controlling them
however if making your own using wrangle I'd avoid trying to manipulate v, P, orient directly, stick to indirect properties like POP nodes do, like v@force, v@torque, v@targetv, v@targetw, f@airresist, ...

Hi Tomas! Thanks so very much for this! I hadn't realized I could use pop nodes in this way, but it does indeed work great.

At the moment, I'm sticking with my RBD sim, though it's pretty slow and hard to iterate as a result. I have around 150,000 bouncy balls; when I try to 'shape' things with a lower sphere count (and correspondingly larger spheres), I can get a look dialed in that seems reasonable, but when I try to sim more/smaller spheres things slow down a lot and the overall shape of the sim changes.

This again encourages me to consider POP grains, if only for the relative speed, but again I'm finding it hard to encourage grains to be very bouncy.