changed shells to a map-indexed system, for identifying new ones

(so far, we can't play the same sound at the same time
anyway, so this change has no visible effect yet)

public/js/main.js

@@ -151,13 +151,19 @@
         
         var animateWorld = function(previousWorld, currentWorld) {
             ctx.clearRect(0, 0, width, height);
-            currentWorld.shells.forEach(function(shell) {
+            var shellMap = currentWorld.shells["shell-map"];
-                drawShell(shell);
+            for (key in shellMap) {
-            });
+                if (shellMap.hasOwnProperty(key)) {
+                    drawShell(shellMap[key]);
+                }
+            }
             currentWorld.robots.forEach(function(robot, idx) {
                 drawRobot(robot, ROBOT_COLORS[idx]);
             });
-            if (currentWorld.shells.length > previousWorld.shells.length) {
+            console.log("next:", currentWorld.shells["next-id"]);
+            console.log("last:", previousWorld.shells["next-id"]);
+
+            if (currentWorld.shells["next-id"] !== previousWorld.shells["next-id"]) {
                 shotSound.play();
             }
         }

src/robotwar/register.clj

@@ -97,20 +97,22 @@
     ; adds a shell to the list of shells.
     ; It's a no-op if the shot clock hasn't reached zero yet.
     {:write-register 
-     (fn [{:keys [robot-idx field-name]} world data]
+     (fn [{:keys [robot-idx field-name]} 
+          {{:keys [shell-map next-id] :as shells} :shells :as world} 
+          data]
        (let [{:keys [pos-x pos-y aim shot-timer] :as robot} 
              (get-in world (path-to-robot robot-idx))]
          (if (> shot-timer 0)
            world
-           (let [shells (:shells world)
+           (let [world-with-new-shot-timer (assoc-in
-                 world-with-new-shot-timer (assoc-in
                                              world
                                              (path-to-robot-field robot-idx :shot-timer)
                                              GAME-SECONDS-PER-SHOT)]
              (assoc 
                world-with-new-shot-timer
                :shells
-               (conj shells (shell/init-shell pos-x pos-y aim data)))))))})
+               {:shell-map (merge shell-map (shell/init-shell pos-x pos-y aim next-id data))
+                :next-id (inc next-id)})))))})
 
 (defn get-target-register
   "helper function for DataRegister record"

src/robotwar/shell.clj

@@ -3,11 +3,12 @@
   (:require [robotwar.physics :as physics]))
 
 (defn init-shell
-  [pos-x pos-y aim distance]
+  [pos-x pos-y aim id distance]
   ; TODO: make the starting point dependent upon the robot radius,
   ; which should be in constants.
   (let [{unit-x :x unit-y :y} (physics/decompose-angle aim)] 
-    {:pos-x pos-x
+    {:id id
+     :pos-x pos-x
      :pos-y pos-y
      :v-x (* unit-x SHELL-SPEED)
      :v-y (* unit-y SHELL-SPEED)

src/robotwar/world.clj

@@ -10,7 +10,8 @@
 (defn init-world
   "initialize all the variables for a robot world."
   [programs]
-  {:shells []
+  {:shells {:next-id 0
+            :shell-map {}}
    :robots (vec (map-indexed (fn [idx program]
                                (robot/init-robot 
                                  idx 
@@ -27,12 +28,12 @@
                                                            (robot/tick-robot (robots robot-idx) world))
                                                          starting-world
                                                          (range (count (:robots starting-world))))
-        ticked-shells (map shell/tick-shell shells)
+        ticked-shells (map shell/tick-shell (:shell-map shells))
         live-shells (remove :exploded ticked-shells)
         exploded-shells (filter :exploded ticked-shells)]
     ; TODO: make this a real let-binding, that determines
     ; which robots were damaged.
     (let [damaged-world ticked-robots-world]
-      (assoc damaged-world :shells live-shells))))
+      (assoc-in damaged-world [:shells :shell-map] live-shells))))
 
 (def build-combined-worlds (partial iterate tick-combined-world))