fix: [#2419] Child entities inherit scene from parent

src/engine/Actor.ts

@@ -369,11 +369,6 @@ export class Actor extends Entity implements Eventable, PointerEvents, CanInitia
    */
   public logger: Logger = Logger.getInstance();
 
-  /**
-   * The scene that the actor is in
-   */
-  public scene: Scene = null;
-
   /**
    * Draggable helper
    */

src/engine/EntityComponentSystem/Entity.ts

@@ -6,7 +6,7 @@ import { OnInitialize, OnPreUpdate, OnPostUpdate } from '../Interfaces/Lifecycle
 import { Engine } from '../Engine';
 import { InitializeEvent, PreUpdateEvent, PostUpdateEvent } from '../Events';
 import { EventDispatcher } from '../EventDispatcher';
-import { Util } from '..';
+import { Scene, Util } from '..';
 
 /**
  * Interface holding an entity component pair
@@ -75,6 +75,11 @@ export class Entity extends Class implements OnInitialize, OnPreUpdate, OnPostUp
    */
   public id: number = Entity._ID++;
 
+  /**
+   * The scene that the entity is in, if any
+   */
+  public scene: Scene = null;
+
   private _name: string = 'anonymous';
   protected _setName(name: string) {
     if (name) {

src/engine/EntityComponentSystem/EntityManager.ts

@@ -54,6 +54,7 @@ export class EntityManager<ContextType = any> implements Observer<RemovedCompone
    */
   public addEntity(entity: Entity): void {
     entity.active = true;
+    entity.scene = (this._world.context as any);
     if (entity && !this._entityIndex[entity.id]) {
       this._entityIndex[entity.id] = entity;
       this.entities.push(entity);
@@ -62,7 +63,10 @@ export class EntityManager<ContextType = any> implements Observer<RemovedCompone
       entity.componentRemoved$.register(this);
 
       // if entity has children
-      entity.children.forEach((c) => this.addEntity(c));
+      entity.children.forEach((c) => { 
+        c.scene = entity.scene;
+        this.addEntity(c);
+      });
       entity.childrenAdded$.register({
         notify: (e) => {
           this.addEntity(e);
@@ -97,13 +101,17 @@ export class EntityManager<ContextType = any> implements Observer<RemovedCompone
 
     delete this._entityIndex[id];
     if (entity) {
+      entity.scene = null;
       Util.removeItemFromArray(entity, this.entities);
       this._world.queryManager.removeEntity(entity);
       entity.componentAdded$.unregister(this);
       entity.componentRemoved$.unregister(this);
 
       // if entity has children
-      entity.children.forEach((c) => this.removeEntity(c, deferred));
+      entity.children.forEach((c) => {
+        c.scene = null;
+        this.removeEntity(c, deferred);
+      });
       entity.childrenAdded$.clear();
       entity.childrenRemoved$.clear();
 

src/spec/EntitySpec.ts

@@ -340,4 +340,41 @@ describe('An entity', () => {
 
     expect(world.entityManager.entities.length).toBe(2);
   });
+
+  it('will inherit scene from a parent entity', () => {
+    const e = new ex.Entity([], 'e');
+    const child = new ex.Entity([], 'child');
+    const grandchild = new ex.Entity([], 'grandchild');
+
+    const scene = new ex.Scene();
+    e.addChild(child.addChild(grandchild));
+    scene.add(e);
+    expect(e.scene).toBe(scene);
+    expect(child.scene).toBe(scene);
+    expect(grandchild.scene).toBe(scene);
+
+    e.removeChild(child);
+    expect(e.scene).toBe(scene);
+    expect(child.scene).toBe(null);
+    expect(child.parent).toBe(null);
+    expect(grandchild.scene).toBe(null);
+    expect(grandchild.parent).toBe(child);
+
+    e.addChild(child);
+    expect(e.scene).toBe(scene);
+    expect(child.scene).toBe(scene);
+    expect(grandchild.scene).toBe(scene);
+
+    // deferred removal
+    scene.remove(e);
+    expect(e.scene).not.toBe(null);
+    expect(child.scene).not.toBe(null);
+    expect(grandchild.scene).not.toBe(null);
+
+    scene.world.entityManager.processEntityRemovals();
+    expect(e.scene).toBe(null);
+    expect(child.scene).toBe(null);
+    expect(grandchild.scene).toBe(null);
+
+  });
 });