refactor main loop, made mistakes, fixed weird thing deep down in collisions

src/cljs/topdown2d/collision.cljs

@@ -58,6 +58,7 @@
   (let [prev (get-in gamestate [:timing :prev])
         now (get-in gamestate [:timing :now])
         secs (/ (- now prev) 1000)
+        secs (-> gamestate :timing :elapsed)
         pps (:pps obj)]
     (* pps secs)))
 

src/cljs/topdown2d/core.cljs

@@ -29,68 +29,56 @@
 
 (def reloaded (atom false))
 
-(defn set-timing
-  "sets the current time at the given key"
-  [state timingkey]
-  (assoc-in state
-            [:timing timingkey]
-            (.now js/performance)))
-
-(defn set-fps
+(defn curr-fps
   "calculates the current fps using the elapsed time"
-  [state]
-  (let [elapsed (-> state :timing :elapsed)
-        fps (/ 1 elapsed)]
-    (assoc-in state [:timing :fps] fps)))
+  [elapsed]
+  (/ 1 elapsed))
+
+(defn elapsed-seconds
+  "calculates the elapsed seconds since the last frame"
+  [gamestate now]
+  (/ (- now (-> gamestate :timing :prev))
+     1000))
 
-(defn set-elapsed-seconds
-  "calculates and writes the elapsed seconds since the last frame"
+(defn curr-scene
+  "returns the current scene"
   [gamestate]
-  (update gamestate
-          :timing
-          #(let [{:keys [now prev]} %]
-             (assoc % :elapsed
-                    (/ (- now prev)
-                       1000)))))
+  (get-in gamestate [:scenes (:scene gamestate)]))
 
-(defn update-scene
+(defn run-scene-update
   "updates the current scene using its udpate function"
-  [gamestate]
-  (if-not (:continue? gamestate)
-    gamestate
-    (let [scenekey (:scene gamestate)
-          {updatefunc :update
-           :as scene} (get-in gamestate [:scenes scenekey])
-          newstate (updatefunc gamestate scene)]
-      (assoc-in gamestate [:scenes scenekey] newstate))))
+  [gamestate scene]
+  ((:update scene) gamestate scene))
 
 (defn continue-running?
   "checks if the gameloop should keep running, based on input"
-  [gamestate]
-  (update
-   gamestate
-   :continue?
-   (fn [continue?]
-     (cond
-       (and continue?
-            (input/keydown? :Digit2)
-            (input/keydown? :ControlLeft)) false
-       (and (not continue?)
-            (input/keydown? :Digit3)
-            (input/keydown? :ControlLeft)) true
-       :else continue?))))
+  [prev-continue?]
+  (cond
+    (and prev-continue?
+         (input/keydown? :Digit2)
+         (input/keydown? :ControlLeft)) false
+    (and (not prev-continue?)
+         (input/keydown? :Digit3)
+         (input/keydown? :ControlLeft)) true
+    :else prev-continue?))
 
 (defn update-step
   "updates timing information and the current scene"
   [gamestate]
-  (-> gamestate
-      (assoc-in [:input :dir] (input/dir))
-      (set-timing :now)
-      (set-elapsed-seconds)
-      (set-fps)
-      (continue-running?)
-      (update-scene)
-      (set-timing :prev)))
+  (let [now (.now js/performance)
+        secs (elapsed-seconds gamestate now)
+        scene (curr-scene gamestate)
+        continue? (continue-running? (:continue? gamestate))]
+    (as-> gamestate $
+      (assoc-in $ [:input :dir] (input/dir))
+      (assoc $ :timing {:now now
+                        :elapsed secs
+                        :fps (curr-fps secs)})
+      (assoc-in $ [:scenes (:scene gamestate)]
+                (if continue?
+                  (run-scene-update $ scene)
+                  scene))
+      (assoc-in $ [:timing :prev] (.now js/performance)))))
 
 (defn draw-fps
   "draws the current fps"
@@ -123,7 +111,6 @@
   then, it calls itself again using requestAnimationFrame"
   [gamestate]
   (let [newstate (update-step gamestate)]
-    (set! (.-imageSmoothingEnabled (:ctx gamestate)) false)
     (draw-step newstate)
     (when-not @reloaded
       (.requestAnimationFrame js/window
@@ -136,6 +123,8 @@
         (-> gamestate :dimensions :w))
   (set! (.-height (:canvas gamestate))
         (-> gamestate :dimensions :h))
+  (set! (.-imageSmoothingEnabled (:ctx gamestate))
+        false)
   (update gamestate
           :scenes
           #(reduce