Hierarchical N-body solver

Fast Multipole
Gravity Lab

Explore softened gravity with adaptive multipole expansions, local fields, and exact near-cell interactions.

M2M → M2L → L2L → P2P

Particles1,024

FPS—

FMM solve—

Quadtree nodes—

M2L interactions—

Sample force error—

Scene

Preset

Particle count

Expansion order

Separation ratio

Leaf capacity

Gravity

Softening

Timestep

Particle trails Quadtree overlay Acceleration vectors Automatic sampled-error check

Click to inject a particle cloud · Shift-click to add a massive body · Space pauses