bbox -100,-100,200,200,true l = 99.9; wall (-1, 0, 1*l), -1*l, 1*l, green wall ( 1, 0, 1*l), -1*l, 1*l, green wall ( 0,-1, 1*l), -1*l, 1*l, green wall ( 0, 1, 1*l), -1*l, 1*l, green bmin = -0.8*l; bmax = 0.8*l; rr = (bmax-bmin)/10; d = 0.2*rr; balltype t1, d, 1, black balltype t2, 2*d, 2, blue for x (-0.4*l:rr:0.8*l) { ball (x,0), (0,0), t1 } ball (-0.9*l,0), (0.4*l,0), t2