Before we dive directly into the code, I would like to briefly outline what we will be doing so that you understand where I am going when we create and add things to the scene.

• 在我们直接深入这个代码之前，我会简述我们要做的事的大致轮廓，这样你就能理解当我们创建并加入一些东西到场景中时，我们的大方向。