KochCurve

KochCurve.fs

namespace TurtleGraphics.Library

module KochCurve =
  open System

  let rec private move n (f: Action<int, int, int, int>) (t:Turtle) =
    match n with
    | 0 ->
      let rad = Math.PI / 180.0
      let x = int (t.step * cos (rad * t.angle)) + t.x
      let y = int (t.step * sin (rad * t.angle)) + t.y
      f.Invoke(t.x, t.y, x, y)
      { t with x = x; y = y}
    | n ->
      [ 60.0; -120.0; 60.0 ]
      |> List.fold (fun t' a -> (move (n-1) f t').turn(a)) t
      |> move (n-1) f

  let private createTurtle n x y max =
    let t = { x = x; y = y; step = max / (3.0 ** float n); angle = 0.0; }
    t

  [<CompiledName "Navigate">]
  let navigate n x y max (f: Action<int, int, int, int>) =
    let t = createTurtle n x y max
    move n f t |> ignore