snow-2011.clj

; The New Year in Snowflakes
; A Clojure doodle by Chouser
(import '(java.awt Color Graphics Frame RenderingHints))

(defonce draw-agent (agent nil))
(defonce halt (atom false))

(defmacro ui-thread [& body]
  `(javax.swing.SwingUtilities/invokeAndWait (fn [] ~@body)))

(def face {
  \0 [[  0  69] [ 40   0] [120   0] [160  69] [160 138]
      [160 207] [120 276] [ 40 276] [  0 207] [  0 138]]
  \1 [[ 11  40] [ 80   0] [ 80  92] [ 80 184] [  0 276] [80 276] [160 276]]
  \2 [[  0  69] [ 40   0] [120   0] [160  69] [120 138] [80 207]
      [ 30 276] [120 276] [200 276]]})

(defn draw-snow [_ g size]
  (ui-thread
    (doto g
      ; clear window
      (.setColor Color/BLACK)
      (.fillRect 0 0 (.width size) (.height size))

      ; draw white snowflakes
      (.setColor Color/WHITE)
      (.setRenderingHint RenderingHints/KEY_ANTIALIASING
                         RenderingHints/VALUE_ANTIALIAS_ON)
      (.setRenderingHint RenderingHints/KEY_RENDERING
                         RenderingHints/VALUE_RENDER_QUALITY)))
  (let [t (.getTransform g)]
    (doseq [[digit col] (map vector "2011" (reductions + [0 290 270 270]))
            [x y] (face digit)
            :let [x (+ 50 x col)
                  y (+ 80 y)
                  a4 (* 2 Math/PI (rand))] ; rotate whole snowflake some
            :while (not @halt)]
      (ui-thread
        (dotimes [i (+ 5 (rand 15))]
          (let [s  (* 20 (rand))  ; length of line
                dx (* 30 (rand))  ; distance of line from center of flake
                a1 (* 2 Math/PI (rand)) ; angle of line around center
                a2 (- (* Math/PI (rand)) (/ Math/PI 2))] ; angle from "spoke"
            (doseq [a3 (range 0 6 (/ Math/PI 3)), flip [1 -1]]
              (doto g
                (.setTransform t)
                (.translate x y)
                (.rotate (+ a4 a3))
                (.scale flip 1)
                (.rotate a1)
                (.translate dx 0.0)
                (.rotate a2)
                (.scale s 1.0)
                (.fillRect 0 0 1 1)))))))))

(defn paint [g size]
  (future
    (reset! halt true)
    (await draw-agent) ; doesn't guarantee much
    (reset! halt false)
    (send-off draw-agent draw-snow g size)))


(defonce frame
  (doto
    (proxy [Frame] ["Happy New Year"]
      (paint [_] (paint (.getGraphics this) (.getSize this))))
    (.setSize 600 700)
    (.setVisible true)))