ThreeLayers实现面积图

Three.js可以通过ThreeLayers实现面积图，具体步骤如下：

1. 创建Three.js场景和ThreeLayers图层。

var scene = new THREE.Scene();
var renderer = new THREE.WebGLRenderer();
document.body.appendChild(renderer.domElement);

var layers = new THREE.Layers();
layers.set(1); //设置图层1为可见
var threeLayer = new THREE.Sprite();
threeLayer.layers = layers;
scene.add(threeLayer);

2. 创建面积图的网格模型。

var geometry = new THREE.Geometry();
geometry.vertices.push(
  new THREE.Vector3(0, 0, 0),
  new THREE.Vector3(0, 1, 0),
  new THREE.Vector3(1, 1, 0),
  new THREE.Vector3(1, 0, 0)
);
geometry.faces.push(new THREE.Face3(0, 1, 2), new THREE.Face3(0, 2, 3));
var material = new THREE.MeshBasicMaterial({ color: 0xff0000 });
var mesh = new THREE.Mesh(geometry, material);
mesh.layers = layers;
threeLayer.add(mesh);

3. 设置Three.js场景相机和渲染器，并渲染场景。

var camera = new THREE.PerspectiveCamera(
  45,
  window.innerWidth / window.innerHeight,
  1,
  1000
);
camera.position.set(0, 0, 5);
renderer.setSize(window.innerWidth, window.innerHeight);

function render() {
  requestAnimationFrame(render);
  renderer.render(scene, camera);
}

render();

这样就可以在Three.js中实现面积图了。其中，ThreeLayers的作用是将图层与场景中的对象进行分离，从而实现对象的独立控制。在上面的代码中，我们将网格模型和ThreeLayer都设置为图层1，然后通过设置ThreeLayer的位置和旋转来控制网格模型的位置和旋转。