Ball models the path of a bouncing object that is reflected by a vibrating surface.
| in | 
 modulated surface level  | 
| g | 
 gravity  | 
| damp | 
 damping on impact  | 
| friction | 
 proximity from which on attraction to surface starts  | 
mouse x controls switch of level:
mouse x controls modulation rate, mouse y controls gravity:
the general german police choir. mouse x controls damping, mouse y controls gravity: