Ocaml - Création d'image en ascii art

type coord = Coord of float*float ;;

let string_of_coord c =
 let Coord(a,b) = c in
  "(" ^ string_of_float a ^ ";" ^ string_of_float b ^ ")"
;;

let coordinate x y =
 Coord(x,y)
;;

let translate_point p v =
 let Coord(px,py) = p in
 let Coord(vx,vy) = v in
Coord(px+.vx,py+.vy)
;;

let inv_translate_point p v =
 let Coord(px,py) = p in
 let Coord(vx,vy) = v in
Coord(px-.vx,py-.vy)
;;

let rotate_point p t =
 let Coord(px,py) = p in
Coord(px*.cos(t)-.py*.sin(t),px*.sin(t)+.py*.cos(t))
;;

let inv_rotate_point p t =
 let Coord(px,py) = p in
Coord(px*.cos(-.t)-.py*.sin(-.t),px*.sin(-.t)+.py*.cos(-.t))
;;

type fig_spec =
 | Circle of float
 | Rectangle of float*float
 | Line of float
;;

type figure =
 Figure of char*(float*float)*float*fig_spec
;;

let circle r =
 Figure('+',(0.,0.),0.,Circle r)
;;

let rectangle w h =
 Figure('+',(0.,0.),0.,Rectangle (w,h))
;;

let line l =
 Figure('+',(0.,0.),0.,Line l)
;;

let color_figure f c =
 let Figure(col,(x,y),ang,spec) = f in
Figure(c,(x,y),ang,spec)
;;

let translate_figure f dx dy =
 let Figure(col,(x,y),ang,spec) = f in
Figure(col,(x+.dx,y+.dy),ang,spec)
;;

let rotate_figure f dt =
 let Figure(col,(x,y),ang,spec) = f in
Figure(col,(x,y),ang+.dt,spec)
;;

let float_abs a =
 if a < 0.
 then -.a
  else a
;;

let intersect_figure grain p f =
 let Figure(_,cent,ang,_) = f in
 let Coord(px,py) = p in
 let p2 = inv_translate_point p cent in
 let p1 = inv_rotate_point p2 ang in
  match f with
   | Figure(x,_,_,Circle r) -> if px*.px+.py*.py <= r*.r then Some x else None
   | Figure(y,_,_,Rectangle (w,h)) -> if float_abs(px) <= w/.2. && float_abs(py) <= h/.2. then Some y else None
   | Figure(z,_,_,Line l) -> if float_abs(px) <= l/.2. && float_abs(py) <= grain then Some z else None
;;