open Jog open Zone;;
let topx = [[0; 1; 2]; [1; 0; 3]; [0; 2; 3]; [2; 1; 3]] in
let (top, fx, tf) = mix (topx, (fun i j -> if i=j then 0. else 1.)) (rp 4) in
let ini = ref {ray = (fun _ -> raise (OffTrack 3));
               curl = (fun _ -> raise (OffTrack 4))} in
let u = (fun t -> ini := t; t)
and v = (fun  x -> {x with ray = (fun fl fa -> print_float fl;
     if fl < 128. then x.ray fl fa else fa)}) in
let bndry = Glue.morphgen (nz (fun i j -> if i=j then 0. else 1.)) top
    (tf [([0; 1], (nop, u)); ([1; 2], (v, v))]) in
(bndry, (!ini).ray 0.0 ([|0.5|], [|0.5; (sqrt 3.) /. 2.|]))
(* Should yield approx ([], ([|0.5; 0.|], [|-0.5; 0.866025403784438708|])) *);;