Threejs第三人称行走

要实现Three.js中的第三人称行走，可以按照以下步骤进行：

1.创建一个场景、相机和渲染器

var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
var renderer = new THREE.WebGLRenderer();
renderer.setSize(window.innerWidth, window.innerHeight);
document.body.appendChild(renderer.domElement);

2.创建一个地面和一个人物角色

var groundGeometry = new THREE.PlaneGeometry(100, 100);
var groundMaterial = new THREE.MeshBasicMaterial({color: 0x00ff00});
var ground = new THREE.Mesh(groundGeometry, groundMaterial);
scene.add(ground);

var characterGeometry = new THREE.BoxGeometry(1, 2, 1);
var characterMaterial = new THREE.MeshBasicMaterial({color: 0xff0000});
var character = new THREE.Mesh(characterGeometry, characterMaterial);
character.position.y = 1;
scene.add(character);

3.设置相机的位置和朝向

camera.position.z = 5;
camera.position.y = 3;
camera.lookAt(character.position);

4.添加键盘控制事件

var keyboard = new THREEx.KeyboardState(renderer.domElement);
var speed = 0.1;

function update() {
  if (keyboard.pressed("left")) {
    character.position.x -= speed;
  }
  if (keyboard.pressed("right")) {
    character.position.x += speed;
  }
  if (keyboard.pressed("up")) {
    character.position.z -= speed;
  }
  if (keyboard.pressed("down")) {
    character.position.z += speed;
  }
}

function render() {
  requestAnimationFrame(render);
  update();
  camera.lookAt(character.position);
  renderer.render(scene, camera);
}

render();

这样，就可以实现一个简单的Three.js第三人称行走。当按下方向键时，角色会在地面上移动，并且相机会跟随角色的移动朝向角色。