IBuffered protocol we snapshot and resture on exception

src/engine.clj

@@ -4,11 +4,32 @@
    [rl :as rl]
    [watch :as w]))
 
+(defprotocol IBuffered
+  (cells [this])
+  (snapshot! [this])
+  (restore! [this]))
+
+(deftype IntGrid [^ints cells ^ints backup]
+  IBuffered
+  (cells [_] cells)
+  (snapshot! [_] (System/arraycopy cells 0 backup 0 (alength cells)))
+  (restore! [_] (System/arraycopy backup 0 cells 0 (alength cells))))
+
+(deftype RawIntGrid [^ints cells]
+  IBuffered
+  (cells [_] cells)
+  (snapshot! [_])
+  (restore! [_]))
+
 (defonce last-error (atom nil))
 (defonce game-state (atom nil))
 (defonce game-config (atom nil))
 (defonce texture-cache (atom {}))
 ;; (reset! texture-cache {})
+(defonce buffered-objs (atom []))
+
+;; TODO: Setup release flags and get this to work with make-int-grid
+;; (def debug? (not= "false" (System/getProperty "siam.debug")))
 
 (defn load-texture-once [id path]
   (or (@texture-cache path)
@@ -16,11 +37,10 @@
         (swap! texture-cache assoc path t)
         t)))
 
-(defn load-texture-once [id path]
-  (or (@texture-cache path)
-      (let [t (assoc (rl/load-texture path) :name id)]
-        (swap! texture-cache assoc path t)
-        t)))
+(defn make-int-grid [n empty-val]
+  (let [g (->IntGrid (int-array n empty-val) (int-array n empty-val))]
+    (swap! buffered-objs conj g)
+    g))
 
 (defn report-exception!
   "Stash the exception and print a marker line. Emacs watches the REPL output
@@ -59,16 +79,22 @@
             (report-exception! t)))
         (while (not (rl/window-should-close?))
           (if @last-error
-            (Thread/sleep 50)
+            (do (rl/with-drawing!)
+                (Thread/sleep 50))
             (let [config (:config @game-config)]
+              (try
+                (doseq [buf @buffered-objs] (snapshot! buf))
+                (swap! game-state #(update config %))
+                (catch Throwable t
+                  (doseq [buf @buffered-objs]
+                    (restore! buf))
+                  (report-exception! t)))
               (rl/with-drawing!
                 (try
-                  (swap! game-state #(update config %))
                   (draw config @game-state)
                   (w/watch! (watch-fn config @game-state))
                   (catch Throwable t
-                    (report-exception! t)
-                    (w/watch! (merge (watch-fn config @game-state) {:error t}))))))))
+                    (report-exception! t)))))))
         (try
           (when unload
             (doseq [[_ tex] @texture-cache]
@@ -77,6 +103,7 @@
           (catch Throwable t
             (report-exception! t)))
         (rl/close-window!)
+        (reset! buffered-objs [])
         (reset! texture-cache {})
         (reset! last-error nil)
         (reset! game-state nil)