(function() { var World = Matter.World, Bodies = Matter.Bodies, Composites = Matter.Composites; Example.beachBalls = function(demo) { var engine = demo.engine, world = engine.world; var stack = Composites.stack(0, 100, 5, 1, 20, 0, function(x, y, column, row) { return Bodies.circle(x, y, 75, { restitution: 0.9 }); }); World.add(world, stack); }; })();