Musing about a game engine

miner.clj

(defprotocol KeyListener 
   (key [this key-code]))

(defprotocol CollisionListener
   (collision [this other]))
   
(defprotocol BoundsListener 
   (bounds [this other]))
   
(defprotocol GravityListener
   (gravity [this time-dif]))
   
(defprotocol PhysicsListener 
   (physics [this time-dif]))
   
(defprotocol Pen 
   (draw [this ctx]))


   
(extend-protocol KeyListener 
   (key [this key-code]))

(extend-protocol CollisionListener
   (collision [this other]))
   
(extend-protocol BoundsListener 
   (bounds [this other]))
   
(extend-protocol GravityListener
   (gravity [this time-dif]))   
   
(extend-protocol PhysicsListener
   object   
   (physics [this ctx]))  
   
(extend-protocol Pen
   object   
   (draw [this ctx]))
   
(extend-protocol PhysicsListener
   object   
   (physics [this ctx frame]))   

   
   

(defn translate-coords [obj frame]
	(assoc obj :x (- (:x obj) (:x frame))
	           :y (- (:y obj) (:y frame))))
			   
   
(defrecord Block [width height x y radii]
  Pen
  (draw [this ctx frame] 
    (let [{:keys [w h color x y radii]} (translate-coords this frame)
	      r (+ x w)
		  b (+ y h)
		  [ul ur lr ll] (or radii [0 0 0 0])]
      (doto ctx
	    (.beginPath)
		(.fillStyle (:color trans))
    (.moveTo (+ x ul) y)
		(.lineTo (- r ur) y)
		(.quadraticCurveTo r y r (+ y ur))
		(.lineTo r (- b lr))
		(.quadraticCurveTo r b (- r lr) b)
		(.lineTo (+ x ll) b)
		(.quadraticCurveTo x b x (- b ll))
		(.lineTo x (+ y ul))
		(.quadraticCurveTo x y (+ x ul) y)))))

		


(defrecord Enemy [img width height coords state])

(defrecord Hero [img width height x y vx vy health score]
   Pen
  (draw [this ctx frame] 
    (let [{:keys [w h img x y]} (translate-coords this frame))]
	  (.drawImage ctx img 0 0 w h)))

	  

(defrecord Reward [img width height coords state])

(defn load-image [img]
  (let [nimg (js/Imgage.)]
    (set! (.-src nimg) img)
	nimg))
	

(defn load-images [app-state]
  (assoc app-state :bodies (reduce #(if (:img %2) 
                                      (conj %1 (assoc %2 :img (load-image img))) 
									                    %1) 
                                   [] 
								                   (:bodies app-state))))
  

(defn draw-world [world ctx]
   (doseq [body (:bodies world)]
     (draw body ctx (:frame world))))



(def world {:board {:width 1000 :height 400 :img nill :color "#7F7FFF"}
            :frame {:width 400 :height 400 :x 0 :y 0}
			      :bodies [#bodies.Hero {:img "jim.png"  :width 30 :height 40 :x 100 :y 200 :vx 0 :vy 0 :health 100 :score 0}
			               #bodies.Block {:color "#007F00" :width 200 :height 100 :x 0 :y 300 :radii [10 10 0 0]}
					           #bodies.Block {:color "#007F00" :width 200 :height 100 :x 200 :y 320 :radii [0 0 0 0]}
					           #bodies.Block {:color "#007F00" :width 200 :height 100 :x 400 :y 300 :radii [10 10 0 0]}
					           #bodies.Block {:color "#007F00" :width 200 :height 100 :x 600 :y 320 :radii [0 0 0 0]}
					           #bodies.Block {:color "#007F00" :width 200 :height 100 :x 800 :y 300 :radii [10 10 0 0]}
					           #bodies.Block {:color "#007F00" :width 200 :height 100 :x 1000 :y 320 :radii [0 10 0 0]}]})
					 
					 
(defn run-game []
  (let [state (load-images world)]
    (draw state)))