// 1. 创建场景
  const scene = new THREE.Scene();

  // 2.创建物体（指定几何体、材质）
  const geometry = new THREE.BoxGeometry(100, 100, 100);
  const material = new THREE.MeshBasicMaterial({
    color: '#f66'
  });
  const mesh = new THREE.Mesh(geometry, material);
  mesh.position.set(0, 10, 0);

  // 3. 把物体放入场景
  scene.add(mesh);

  // --------------------
  
  // 4. 创建相机
  const camera = new THREE.PerspectiveCamera();
  camera.position.set(200, 200, 200);
  camera.lookAt(mesh.position);

  // --------------------

  // 5. 创建渲染器（指定画布大小, 渲染场景、相机）
  const renderer = new THREE.WebGLRenderer();
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.render(scene, camera);
  document.body.appendChild(renderer.domElement);