Play (wrong) door sound effect when the door opens or closes

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_entities/lib/src/entities/door.dart

@@ -3,54 +3,47 @@ enum DoorState { closed, opening, open, closing }
 class Door {
   final int x;
   final int y;
-  final int mapId; // To differentiate between regular doors and elevator doors
+  final int mapId;
 
   DoorState state = DoorState.closed;
   double offset = 0.0;
-  int openTime = 0; // When did the door fully open?
-
-  // How long a door stays open before auto-closing
+  int openTime = 0;
   static const int openDurationMs = 3000;
 
-  Door({
-    required this.x,
-    required this.y,
-    required this.mapId,
-  });
-
-  // Returns true if the door state changed this frame (useful for playing sounds later)
-  bool update(int currentTimeMs) {
-    bool stateChanged = false;
+  Door({required this.x, required this.y, required this.mapId});
 
+  /// Updates animation. Returns the NEW state if it changed this frame, else null.
+  DoorState? update(int currentTimeMs) {
     if (state == DoorState.opening) {
-      offset += 0.02; // Slide speed
+      offset += 0.02;
       if (offset >= 1.0) {
         offset = 1.0;
         state = DoorState.open;
         openTime = currentTimeMs;
-        stateChanged = true;
+        return DoorState.open;
       }
     } else if (state == DoorState.open) {
       if (currentTimeMs - openTime > openDurationMs) {
         state = DoorState.closing;
-        stateChanged = true;
+        return DoorState.closing;
       }
     } else if (state == DoorState.closing) {
-      // Note: We don't check for entities blocking the door yet!
       offset -= 0.02;
       if (offset <= 0.0) {
         offset = 0.0;
         state = DoorState.closed;
-        stateChanged = true;
+        return DoorState.closed;
       }
     }
-
-    return stateChanged;
+    return null;
   }
 
-  void interact() {
+  /// Triggers the opening process. Returns true if it successfully started opening.
+  bool interact() {
     if (state == DoorState.closed || state == DoorState.closing) {
       state = DoorState.opening;
+      return true;
     }
+    return false;
   }
 }