问如何在轴上旋转3D对象

EN

var scene, renderer, camera;
var cube;
var controls;
var containerWidth = window.innerWidth,
  containerHeight = window.innerHeight;
var isDragging = false;
var previousMousePosition = {
  x: 0,
  y: 0
};

init();

animate();

function init() {
  configureRenderer();
  scene = new THREE.Scene();
  configureCube();
  configureCamera();
  configureLight();
  configureControls();
}

function configureRenderer() {
  renderer = new THREE.WebGLRenderer({
    antialias: true,
    alpha: true
  });
  renderer.setSize(innerWidth, innerHeight);
  document.body.appendChild(renderer.domElement);
  window.onresize = function() {
    renderer.setSize(window.innerWidth, window.innerHeight);
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    if (controls) controls.handleResize();
  };
}

function configureCube() {
  var cubeGeometry = new THREE.BoxGeometry(20, 20, 20);
  var cubeMaterial = new THREE.MeshLambertMaterial({
    color: 0xff0000
  });
  cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
  cube.position.set(50, 0, 0);
  scene.add(cube);
  cubeGeometry.center();
}

function configureCamera() {
  camera = new THREE.PerspectiveCamera(
    45,
    containerWidth / containerHeight,
    1,
    1000
  );
  camera.position.set(0, 160, 400);
  camera.lookAt(scene);
}

function configureLight() {
  pointLight = new THREE.PointLight(0xffffff, 1.0, 100000);
  pointLight.position.set(0, 300, 200);
  scene.add(pointLight);
}

function configureControls() {
  controls = new THREE.TrackballControls(camera, renderer.domElement);
  controls.enabled = false;
  controls.update();

  document.addEventListener("mousedown", onMouseDown, false);
  document.addEventListener("mouseup", onMouseUp, false);
}
function onMouseDown() {
  previousMousePosition.x = event.clientX;
  previousMousePosition.y = event.clientY;
  document.addEventListener("mousemove", onMouseMove, false);
}
function onMouseMove(event) {
  var rotationX = event.clientX - previousMousePosition.x;
  var rotationY = event.clientY - previousMousePosition.y;

  previousMousePosition.x = event.clientX;
  previousMousePosition.y = event.clientY;

  if (rotationX || rotationY) {
    rotateAroundWorldAxis(cube, new THREE.Vector3(0, 1, 0), rotationX * 0.01);
    rotateAroundWorldAxis(cube, new THREE.Vector3(1, 0, 0), rotationY * 0.01);
  }
}
function onMouseUp() {
  document.removeEventListener("mousemove", onMouseMove, false);
}
function rotateAroundWorldAxis(object, axis, radians) {
  var rotationMatrix = new THREE.Matrix4();
  rotationMatrix.makeRotationAxis(axis.normalize(), radians);
  rotationMatrix.multiply(object.matrix);
  object.matrix = rotationMatrix;
  object.rotation.setFromRotationMatrix(object.matrix);
}
function animate() {
  controls.update();
  requestAnimationFrame(animate);
  renderer.render(scene, camera);
}