Pass display into fns rather than using atoms

common/src/cljx/enoki/engine.cljx

@@ -12,29 +12,18 @@
                    )
          (:require-macros [enoki.util.logging-macros :as log]))
 
-(def get-display
-  "Function that returns the graphics display"
-  (atom nil))
-
-(defn- init-platform-bindings!
-  "Populates the environment with various platform-specific functions."
-  [{:keys [display]}]
-  (log/info "Establishing platform-specific bindings")
-  (reset! get-display (constantly display)))
-
-(defn render [display state]
-  (-> (g/context display)
+(defn render [ctx state]
+  (-> ctx
       (g/clear!)
       (g/draw-text! "Hello, world" 10 20)))
 
-(defn tick [state]
-  (render (@get-display) state))
+(defn tick [{:keys [state display]}]
+  (render (g/context display) state))
 
 (defn start
   "Enters the game loop. This function might return immediately or once the game
    loop is exited, depending on the implementation of loop-fn."
-  [env initial-state]
-  (init-platform-bindings! env)
+  [env]
   (log/info "Entering game loop")
   (let [loop-forever (:loop-fn env)]
-    (loop-forever tick initial-state)))
+    (loop-forever tick env)))

swing/src/enoki/engine_impl.clj

@@ -3,7 +3,7 @@
 (defn loop-forever
   "A naïve game loop implementation that sleeps for 1 millisecond between
    calls to `tick'."
-  [tick initial-state]
-  (loop [state initial-state]
+  [tick env]
+  (loop [env env]
     (Thread/sleep 1)
-    (recur (tick state))))
+    (recur (tick env))))

swing/src/enoki/main.clj

@@ -6,5 +6,5 @@
 
 (defn start
   "Engine entry point"
-  [env initial-state]
-  (engine/start (assoc env :loop-fn impl/loop-forever) initial-state))
+  [env]
+  (engine/start (assoc env :loop-fn impl/loop-forever)))

swing/src/game/swing/main.clj

@@ -17,8 +17,8 @@
 (defn init []
   (let [screen (create-screen)]
     (seesaw/invoke-now (seesaw/show! (create-frame screen)))
-    (enoki/start {:display (gfx/->JComponentDisplay screen)}
-                 {})))
+    (enoki/start {:display (gfx/->JComponentDisplay screen)
+                  :state {}})))
 
 (defn -main [& args]
   (init))

web/src/cljs/enoki/engine_impl.cljs

@@ -1,5 +1,5 @@
 (ns enoki.engine-impl
   (:require [goog.Timer :as timer]))
 
-(defn loop-forever [tick state]
-  (timer/callOnce #(loop-forever tick (tick state)) 1))
+(defn loop-forever [tick env]
+  (timer/callOnce #(loop-forever tick (tick env)) 1))

web/src/cljs/enoki/main.cljs

@@ -8,8 +8,8 @@
 
 (defn start
   "Engine entry point"
-  [env initial-state]
+  [env]
   (repl/connect "http://localhost:9000/repl")
   (logging/init!)
   (logging/set-level! :info)
-  (engine/start (assoc env :loop-fn impl/loop-forever) initial-state))
+  (engine/start (assoc env :loop-fn impl/loop-forever)))

web/src/cljs/game/web/main.cljs

@@ -4,5 +4,5 @@
             [enoki.util.dom :as dom]))
 
 (defn ^:export init []
-  (enoki/start {:display (gfx/->CanvasDisplay (dom/get-element "screen"))}
-               {}))
+  (enoki/start {:display (gfx/->CanvasDisplay (dom/get-element "screen"))
+                :state {}}))