refactor: room world property

packages/entity/traits/physical.js

@@ -45,6 +45,12 @@ export class Physical extends decorate(Trait) {
   }
 
   set world(world) {
+    if (this._world) {
+      this._world.removeBody(this._body);
+    }
+    if (this.bodyView) {
+      this.bodyView.destroy();
+    }
     this._world = world;
     if (world) {
       const body = world.createBody(this.entity.shape);

packages/topdown/room.js

@@ -1,12 +1,15 @@
 import * as I from 'immutable';
 
 import {compose} from '@avocado/core';
-import {EventEmitter} from '@avocado/mixins';
+import {EventEmitter, Property} from '@avocado/mixins';
 
 import {Layers} from './layers';
 
 const decorate = compose(
   EventEmitter,
+  Property('world', {
+    track: true,
+  }),
 );
 
 class RoomBase {
@@ -14,7 +17,6 @@ class RoomBase {
   constructor() {
     this.layers = new Layers();
     this._state = I.Map();
-    this._world = undefined;
     // Listeners.
     this.onEntityAddedToRoom = this.onEntityAddedToRoom.bind(this);
     this.onEntityRemovedFromRoom = this.onEntityRemovedFromRoom.bind(this);
@@ -34,6 +36,9 @@ class RoomBase {
 
   destroy() {
     this.layers.destroy();
+    this.layers.off('entityAdded', this.onEntityAddedToRoom);
+    this.layers.off('entityRemoved', this.onEntityRemovedFromRoom);
+    this.off('worldChanged', this.onWorldChanged);
   }
 
   fromJSON(json) {
@@ -56,6 +61,16 @@ class RoomBase {
     this.emit('entityRemoved', entity);
   }
 
+  onWorldChanged() {
+    for (const layer of this.layers) {
+      for (const entity of layer.entityList) {
+        if (entity.is('physical')) {
+          entity.world = this.world;
+        }
+      }
+    }
+  }
+
   removeEntityFromLayer(entity, layerIndex = 0) {
     this.layers.removeEntityFromLayer(entity, layerIndex);
   }
@@ -67,19 +82,19 @@ class RoomBase {
   tick(elapsed) {
     this.layers.tick(elapsed);
     this._state = this._state.set('layers', this.layers.state);
-    if (this._world) {
-      this._world.tick(elapsed);
+    if (this.world) {
+      this.world.tick(elapsed);
     }
   }
 
-  get world() {
-    return this._world;
-  }
-
-  set world(world) {
-    this._world = world;
-  }
-
 }
 
-export class Room extends decorate(RoomBase) {}
+export class Room extends decorate(RoomBase) {
+
+  constructor() {
+    super();
+    this.onWorldChanged = this.onWorldChanged.bind(this);
+    this.on('worldChanged', this.onWorldChanged);
+  }
+
+}