如何在Three.js中获取摄像机上可见的所有对象

var visibleObjects = [];

var cameraPosition = camera.position;
var cameraDirection = camera.getWorldDirection(new THREE.Vector3());

scene.traverse(function(object) {
  if (object.visible) {
    var objectPosition = object.getWorldPosition(new THREE.Vector3());
    var direction = objectPosition.clone().sub(cameraPosition);
    var distance = direction.length();

    direction.normalize();

    var dotProduct = direction.dot(cameraDirection);

    // 判断对象是否在摄像机的视锥体内
    if (dotProduct > 0 && distance < camera.far) {
      visibleObjects.push(object);
    }
  }
});