Godel Escher Bach - G fractal from Chapter 5

godel-escher-bach-g-fractal.cljs

;; Godel Escher Bach - G fractal from Chapter 5
(set!
  (.-innerHTML js/klipse-container)
  "<canvas style='width:100%; height:100%'></canvas>")
(def canvas (aget (js/document.getElementsByTagName "canvas") 0))

(set! (.-height canvas) (.-innerHeight js/window))

(def ctx (.getContext canvas "2d"))

(defn circle [ctx x y]
  (.beginPath ctx)
  (set! (.-fillStyle ctx) "black")
  (.arc ctx x y 2.5 0 (* 2  js/Math.PI))
  (.stroke ctx)
  (.fill ctx))

(defn connect [ctx side x y width]
  (let [x-end (if (= side :left)
                (- x width) (+ x width))]
    (.beginPath ctx)
    (.moveTo ctx x y)
    (.lineTo ctx x-end y)
    (.moveTo ctx x-end y)
    (.lineTo ctx x-end (- y 10))
    (.stroke ctx)
    (.moveTo ctx x y)))

(defn connect-up [ctx x y]
  (.beginPath ctx)
  (.moveTo ctx x y)
  (.lineTo ctx x (- y 10))
  (.stroke ctx)
  (.moveTo ctx x (- y 10)))

(defn draw-right [x y n width]
  (connect ctx :right x y width)
  (circle ctx (+ x width) (- y 10))
  (draw (+ x width) (- y 10) (dec n) (/ width 2)))

(defn draw-left [x y n width]
  (connect ctx :left x y width)
  (draw (- x width) (- y 10) (dec n) (/ width 2)))

(defn draw [x y n width]
  (when (> n 0)
    (connect-up ctx x y)
    (circle ctx x (- y 10))
    (draw-left x (- y 10) n width)
    (draw-right x (- y 10) n width)))

(draw (/ (.-width canvas) 2) 200 5 75)

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