Particle Sim
Simulate points as particles of dust, sparks, or debris. Self-collision makes them a granular material: sand, snow, or gravel.
What it does
Takes a point cloud, from Scatter or any Points source, and turns each point into a simulated particle for Physics World to integrate under gravity and forces. Self Collision decides which kind of particle results. Off, particles are force-driven and pass through each other, suiting dust, sparks and spray, while still landing on the ground and on colliders. On, particles collide with their neighbours and settle into a pile, giving granular materials like sand, snow or gravel.
With Self Collision on, Friction and Cohesion shape the pile, from dry loose grains to wet clumping ones. Restitution and Damping apply either way, controlling bounciness and how fast motion dies down.
When to use it
Scattering dust, sparks or debris that never collides with itself: Self Collision off
Sand, snow, gravel or sugar that piles up and flows: Self Collision on, then tune Friction and Cohesion
A point cloud from Scatter, or geometry sampled into points, that should fall, bounce and settle physically
Particles that still land on the ground or other colliders with Self Collision off
| Parameter | Type | Default |
|---|---|---|
input | OneOf([CollectionOf(Points), CollectionOf(Geometry)]) | — |
self_collision | Boolean | true |
particle_radius | Number | 0.050 |
friction | Number | 0.500 |
restitution | Number | 0.300 |
cohesion | Number | 0 |
damping | Number | 0.010 |
strength | Number | 1 |
Gotchas
Particle Radius, Friction and Cohesion apply, and appear, only when Self Collision is on. They have no effect on pass-through dust or sparks.
Cohesion is the dry-to-wet dial for granular material: 0 gives loose dry sand, around 0.5 gives clumping wet sand, and 1 gives snow-like stickiness.
Self Collision is a structural switch rather than a look-and-feel dial. It changes which contacts the solver considers, so flipping it costs a brief recompile and re-settle, unlike the other sliders, which animate smoothly.
Particle Sim only stamps particle settings onto the point cloud. It does not simulate on its own. Feed its output into Physics World to run the simulation.
Worked example
Scatter points across a surface to seed the particles, then feed them into Particle Sim.
Leave Self Collision on and raise Cohesion for a pile of wet sand, or turn Self Collision off for a burst of sparks that pass through each other.
Wire the output into Physics World so the particles fall, bounce and settle.
Adjust Restitution for bounciness and Damping to control how quickly motion dies down.