老师你好，关于5-11我照着教程写有个bug解决不了。

这种情况下，会报错scene为未定义。要是改变这两行的代码顺序则会报

报错的原因是
this.texture.needsUpdate = true;
这一行代码。
下面是gameOverPage类的代码
`export default class GameOverPage {

constructor(callbacks) {
this.callbacks = callbacks;
}

init(options) {
console.log(‘gameOverPage.init’);
this.initGameOverCanvas(options);
}

//创建一个canvas绘制2D图片并将canvas当做纹理绘制到three.js的对象上
initGameOverCanvas(options) {
this.scene = options.scene;
this.camera = options.camera;

const aspect = window.innerHeight / window.innerWidth;
this.canvas = document.createElement('canvas');
this.canvas.width = window.innerWidth;
this.canvas.height = window.innerHeight;
this.texture = new THREE.Texture(this.canvas);

this.material = new THREE.MeshBasicMaterial({
  map: this.texture, 
  transparent: true,
  side: THREE.DoubleSide
})

this.geometry = new THREE.PlaneGeometry(window.innerWidth,window.innerHeight);
this.object = new THREE.Mesh(this.geometry,this.material);
this.object.position.z = 1;

this.context = this.canvas.getContext('2d');
this.context.fillStyle = '#333';
this.context.fillRect((window.innerWidth - 200) / 2, (window.innerHeight - 100) / 2, 200, 100);
this.context.fillStyle = '#eee'
this.context.font = '20px Georgia'
this.context.fillText('Game Over', (window.innerWidth - 200) / 2 + 50, (window.innerHeight - 100) / 2 + 55)
this.texture.needsUpdate = true;
this.scene.add(this.object);

}

show() {
console.log(‘gameOverPage.show’)
}
}`