@modoki/engine / index / Physics3D

Variable: Physics3D

const Physics3D: Trait<{ gravityX: number; gravityY: number; gravityZ: number; unitsPerMeter: number; }>

Singleton 3D physics world config (one per scene, like Time). If absent, the physics system falls back to these same defaults, so dropping a RigidBody3D "just works" without authoring a Physics3D entity.

gravityX/Y/Z are a physical acceleration in m/s² (NOT world units) — independent of unitsPerMeter — in the Three.js frame (+Y up). Unlike the 2D world there is NO axis flip: "down" is negative Y, so the default is (0, -9.81, 0), handed straight to Rapier's Y-up world.

unitsPerMeter is the scale between world units and Rapier meters. Default 1 (3D world units already are meters, keeping bodies in the solver's happy 0.1–10 m range). Existing collider sizes are baked at creation, so change it before Play (Phase 1).