Why Hash Grids Beat Sparse Trees for Particle Simulation, From the Author

Michael_Moroz_ · x · 2026-09-10

Following up on his VRChat fluid simulation, the author explains the technical choice: hash-based particle simulation beats sparse tree grids because sparse trees require indirections to find neighbors, while hash grids' only downside is hash collisions — and with latency as the bottleneck, hash grids win.

He's also improving the isosurface ray tracer with more PBR-style rendering and basic screen-space effects, currently only in bounded mode; making it performant in boundless hash-sparse mode remains an open problem.

Related event: Developer Unbounds Million-Particle Fluid Simulation in VRChat via Hash Grid(4 posts)→

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