Animating a pile-up using physics

I’m trying to figure out the best way and how to animate a pile-up. Picture a thousand objects rapidly falling from a specific point in space. When they hit the ground, they’ll deflect a bit but eventually stop due to friction and from being pounded on by the objects falling above it. Ultimately this will form a mountain. I’ve tried to do this with a particle emitter and added deflection on the surface and objects, but the particles don’t stack up on top of each other. Instead, when they hit the ground they begin to spread out like a pancake and continue moving off without stopping. The deflection also seemed to add a weird behavior to the falling objects. At some point, they begin to get sucked in by the deflected objects and gain incredible velocity. Seems a lot like a black hole effect.

I also thought about using an array to copy the object a thousand times and using Blender’s physics engine to drop them all at once, but with an array I don’t get the quick animation due to the large distances from the ground created from the array.

I don’t know at this point. Can anyone offer suggestions?

I think you kinda answered your own question, there isn’t any friction. You may have to create an invisible obstacle to hold them in and simulate the friction needed to stop the objects from spreading out on the ground, possibly even a cone shaped cage so they don’t fall off the sides of the pile. Even that may not be quite enough, you may have to start with a smaller cone and then expand it to hold all the objects.


Have a look at the following. It is from the release log from an earlier version, so some of the screens may be different, but the concepts still apply.

The cone idea was interesting, but it doesn’t work out the way I’d like it too. The particles still have a tendency to flatten out like a pancake, so they’re not piling up. When they do reach the border of the cone, some of them start to bounce up and down a bit while a few others leak through and start doing some wobbling all over the place. I did set permeability to 1, with the key set to 100.

As far as I know, Bullet physics don’t apply to particle emitters. For my alternative approach, I could use the physics engine to drop 1000+ copies of the object I’m using (approx 10,000 tris per model x 1000 = slow processing ;), but then I need a way to “pour” them out like a particle emitter would, or in the same sense as the fluid dynamics. The array modifier unfortunately doesn’t allow me to do something like that.

Can you turn up the damping? That might help. Sorry, not to familiar with blender’s physics. I would have thought the cone idea would have had a little more promise since it’s simple calculus, er, maybe not so simple, but that’s kinda how stuff piles up.