让球体在直线渲染器中两点之间移动？

// 创建场景和相机
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
camera.position.z = 5;

// 创建渲染器
const renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

// 创建球体
const radius = 0.5;
const segments = 32;
const material = new THREE.MeshBasicMaterial({ color: 0xff0000 });
const sphere = new THREE.Mesh(new THREE.SphereGeometry(radius, segments, segments), material);
scene.add(sphere);

// 设置起点和终点
const startPosition = new THREE.Vector3(-2, 0, 0);
const endPosition = new THREE.Vector3(2, 0, 0);

// 计算移动方向和速度
const direction = endPosition.clone().sub(startPosition).normalize();
const speed = 0.05;

function animate() {
  requestAnimationFrame(animate);

  // 更新球体位置
  sphere.position.add(direction.clone().multiplyScalar(speed));

  // 判断是否到达终点，如果到达则重置位置到起点
  if (sphere.position.distanceTo(endPosition) < speed) {
    sphere.position.copy(startPosition);
  }

  // 渲染场景
  renderer.render(scene, camera);
}

animate();