three.js尺寸标注

// 创建场景、相机和渲染器
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
const renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

// 创建一个立方体
const geometry = new THREE.BoxGeometry();
const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 });
const cube = new THREE.Mesh(geometry, material);
scene.add(cube);

// 创建一个尺寸标注（箭头）
const arrow = new THREE.ArrowHelper(
  new THREE.Vector3(1, 0, 0), // 方向向量
  new THREE.Vector3(0, 0, 0), // 起始点
  2, // 长度
  0xff0000, // 颜色
  0.5 // 箭头头部大小
);
scene.add(arrow);

// 设置相机位置
camera.position.z = 5;

// 渲染循环
function animate() {
  requestAnimationFrame(animate);
  cube.rotation.x += 0.01;
  cube.rotation.y += 0.01;
  renderer.render(scene, camera);
}
animate();