Real-time physics simulator
Physics Sketchbook
Drop a body, pick its material and watch it fall, bounce or shatter in 3D, with the exact formulas and the measured values updating live beside it.
ReactTypeScriptReact Three FiberRapierZustandKaTeXBun
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Overview
A physics sandbox with a technical-blueprint look. Its first module, free fall, runs on the Rapier physics engine: real collisions, bounce that depends on the material, and fracture (glass shatters, concrete and wood break into chunks, steel dents).
What it does
- Ten materials with their own density, bounciness, friction and hardness.
- Deterministic, seeded fracture: the same drop breaks the same way every time.
- Every run is recorded frame by frame, so the timeline scrubs back and forth through the replay.
- A live formula panel (KaTeX) with the measured position, velocity and energy, plus CSV export.
My role
The idea came from a friend; I designed and built almost all of it, from March to July 2026. A Bun monorepo with the pure solvers in their own package, Biome, lefthook and CI.