rectangle

(def ^:dynamic *current-canvas* nil)

(def key-pressed-count (atom 0))

(defn tick-and-bloom 
  [interval 
   [init-bloom-value f-on-bloom-in-every-tick] 
   [reset-pred & t-args]]
  (fn [f]
    (loop [to-bloom init-value]
      (Thread/sleep interval)
      (f to-bloom)
      (recur ((if-not (apply terminate-pred t-args)
                f-on-bloom-in-every-tick
                (constantly init-value)) to-bloom)))))

;;matrix-multiply is not a function in clojure.core, 
;;but a function pretend to have been defined in this program, sin & cos as well
;;point is in the structure of [x y]
(defn spinned-point [angle point]
  (pop
    (multiply (conj point 1)
              [[(cos angle) -(sin angle) 0]
               [(sin angle) (cos angle) 0]
               [0 0 1]])))

(defn gen-rectangle-points-according-to-size-and-angle
  [size angle]
  (map (partial spinned-point angle)
       (map (partial map (partial * size)) 
            [[1 1] [1 -1] [-1 -1] [-1 1]])))

;;clear-and-redraw is a function pretended to be exist, again, not in clojure.core.
;;create-canvasand  key-pressed? as well
;;but there's similar functions in see-saw library, see http://daveray.github.io/seesaw/seesaw.graphics-api.html
(defn draw-spinned-square [size angle]
  (clear-and-redraw :polygon *current-canvas*
                    (gen-rectangle-points-according-to-size-and-angle size angle)))

(defn -main []
  (binding [[width height] [640 480]
            *current-canvas* (create-canvas width height)]
    (future
      ((tick-and-bloom 
         1 [1 inc] 
         [key-pressed? :space])
       (fn [x] (draw-spinned-square x x))))))