Ronin: Drawing a Bézier Curve

bezier.lisp

(defn bezier-line 
  (points color) 
  (
    (def ts (range 0 1 .001)) 
    ; Calculate the coordniates of the bezier curve:
    (defn bezier-point 
      (t x0 x1 x2) 
      (add x1 
        (mul 
          (pow 
            (sub 1 t) 2) 
          (sub x0 x1)) 
        (mul 
          (pow t 2) 
          (sub x2 x1))))
    ; Draw Point on the curve:
    (defn draw 
      (t0) 
      (
        (def p0 (:0 points))
        (def p1 (:1 points)) 
        (def p2 (:2 points)) 
        (fill 
          (rect 
            (bezier-point t0 p0:x p1:x p2:x) 
            (bezier-point t0 p0:y p1:y p2:y) 1 1) color))) 
    (each ts draw)))

; Start Definition of Drawing
(clear)
(def anchor-a (guide $pos))
(def control  (guide $pos))
(def anchor-b (guide $pos))
(bezier-line (anchor-a control anchor-b) "red")