Grass interactors that follow the wheels of a fleet's vehicles: one Object3D per tyre, parented to
the fleet so world positions are right wherever the fleet is. Pass interactors to
threejs-grass (grass.set({ interactors })) and call update() after fleet.update().
Grass interactors that follow the wheels of a fleet's vehicles: one
Object3Dper tyre, parented to the fleet so world positions are right wherever the fleet is. Passinteractorsto threejs-grass (grass.set({ interactors })) and callupdate()afterfleet.update().Example