init

src/lib/Movable.ts

 import Vector2 from "./Vector2";
 
 export default class Movable extends FYGE.Sprite {
+    getCanRemove() {
+        return true;
+    }
     private _velocity: Vector2;
 
     set velocity(val: Vector2) { this._velocity = val }

src/lib/MovableManager.ts

@@ -78,7 +78,8 @@ export default class MovableManager extends FYGE.EventDispatcher {
         return x0 < x1 && y0 < y1;
     }
 
-    private calcCanRemove(item: FYGE.DisplayObject) {
+    private calcCanRemove(item: Movable) {
+        if (!item.getCanRemove()) return;
         if (item.y > 1624) return true;
         if (item.y < -item.height) return true;
         if (item.x > 750) return true;

src/planewar/Background.ts

+import Movable from "../lib/Movable";
+import MovableManager from "../lib/MovableManager";
+import Vector2 from "../lib/Vector2";
+class BackgroundItem extends Movable {
+    constructor() {
+        super();
+        this.texture = FYGE.Texture.fromUrl('//yun.duiba.com.cn/aurora/assets/bd7b3b10169265123e52d02acf8739db5ff59b3d.png');
+        this.velocity = new Vector2(0, 10)
+    }
+    getCanRemove() { return false }
+}
+const height = 1624;
+export default class Background {
+
+    constructor(stage: FYGE.Stage, movableManager: MovableManager) {
+        var bg = new BackgroundItem();
+        var bg2 = new BackgroundItem();
+
+        movableManager.add(bg);
+        movableManager.add(bg2);
+
+        stage.addChild(bg);
+        stage.addChild(bg2);
+
+        bg.x = 0;
+        bg2.y = height;
+
+        stage.addEventListener(FYGE.Event.ENTER_FRAME, () => {
+            if (bg.y > height) {
+                bg.y = bg2.y - height;
+            }
+            if (bg2.y > height) {
+                bg2.y = bg.y - height;
+            }
+        });
+    }
+}
\ No newline at end of file

src/planewar/addGame.ts

 import DragDropManager from "../dragdrop/DragDropManager";
 import MovableManager from "../lib/MovableManager";
+import Background from "./Background";
 import EnemyFactory from "./EnemyFactory";
 import Hero from "./Hero";
 
@@ -8,6 +9,8 @@ export function addGame(stage: FYGE.Stage) {
     const movableManager = new MovableManager(stage);//创建管理器
     const dragDropManager = new DragDropManager();
 
+    const background = new Background(stage, movableManager);
+
     const hero = stage.addChild(new Hero(movableManager));
     hero.position.set(300, 1000);
 
@@ -22,4 +25,6 @@ export function addGame(stage: FYGE.Stage) {
         dragDropManager.remove(hero);
     }
     movableManager.addEventListener('gameover', onGamOver);
+
+
 }
\ No newline at end of file