thank you for the flowers here's a fixed version : http://www.babylonjs-playground.com/#25OQ8V#13 the parameter CAP was added just after the old PG link, so I just added its value (0 or null) before the parameter scene in all calls to CreateTube(). Yep, as @fenomas said, everything that manages the behaviour of the objects in a scene according to external forces (gravity) or internal values (mass, elasticity, initial velocity, etc) could be called a physics engine. Whether it's mi