物理cannon使用 · Physics Mesh · ▶ 在线运行案例

• 案例合集： 三维可视化功能案例（threehub.cn）
• 开源仓库github地址： https://github.com/z2586300277/three-cesium-examples
• 400个案例代码: 网盘链接

你将学到什么

• OrbitControls 相机轨道交互
• 物理引擎刚体碰撞
• requestAnimationFrame 渲染循环与 resize 自适应

效果说明

本案例演示 物理cannon使用 效果：基于 WebGL 实现「物理cannon使用」可视化效果，附完整可运行源码；核心用到 OrbitControls、物理引擎刚体碰撞。建议先打开文首在线案例查看动态画面，再对照下方源码逐步理解。

核心概念

• OrbitControls 轨道旋转缩放；开 enableDamping 时每帧需 controls.update()。

实现步骤

• 搭建 Scene / Camera / Renderer 与 OrbitControls
• rAF 循环中 update 并 render

• 代码要点

  import * as THREE from 'three'
  import { OrbitControls } from 'three/examples/jsm/controls/OrbitControls.js'
  import * as CANNON from 'cannon-es';
  
  const box = document.getElementById('box')
  
  const scene = new THREE.Scene()
  
  const camera = new THREE.PerspectiveCamera(75, box.clientWidth / box.clientHeight, 0.1, 1000)
  
  camera.position.set(0, 10, 10)
  
  const renderer = new THREE.WebGLRenderer()
  
  renderer.setSize(box.clientWidth, box.clientHeight)
  
  box.appendChild(renderer.domElement)
  
  new OrbitControls(camera, renderer.domElement)
  
  scene.add(new THREE.AxesHelper(5000), new THREE.AmbientLight(0xffffff, 0.5))
  
  const pointLight = new THREE.PointLight(0xffffff, 3, 0)
  
  pointLight.position.set(0, 2, 0)
  
  scene.add(pointLight)
  
  const world = new CANNON.World({ gravity: new CANNON.Vec3(0, -9.82, 0) })
  
  // 渲染时间略有不同的时间显示物理模拟的状态
  world.PhysicsRender = (deltaTime) => {
  
  world.step(1 / 60, deltaTime, 3)
  
  world.bodies.forEach(body => body.render?.())
  
  }
  
  // 创建一个立方体
  const cubeGeometry = new THREE.BoxGeometry(1, 1, 1)
  
  const cubeMaterial = new THREE.MeshStandardMaterial({ color: 0xffffff })
  
  const cubeMesh = new THREE.Mesh(cubeGeometry, cubeMaterial)
  
  cubeMesh.position.set(0, 5, 0)
  
  createPhysicsBody(world, cubeMesh, 1)
  
  scene.add(cubeMesh)
  
  // 创建一个平面
  const planeGeometry = new THREE.PlaneGeometry(10, 10)
  
  const planeMaterial = new THREE.MeshStandardMaterial({ color: 0xffffff, side: THREE.DoubleSide })
  
  const planeMesh = new THREE.Mesh(planeGeometry, planeMaterial)
  
  planeMesh.rotation.x = Math.PI / 2
  
  createPhysicsBody(world, planeMesh, 0)
  
  scene.add(planeMesh)
  
  animate()
  
  function animate() {
  
  requestAnimationFrame(animate)
  
  world.PhysicsRender()
  
  renderer.render(scene, camera)
  
  }
  
  window.onresize = () => {
  
  renderer.setSize(box.clientWidth, box.clientHeight)
  
  camera.aspect = box.clientWidth / box.clientHeight
  
  camera.updateProjectionMatrix()
  
  }
  
  function createPhysicsBody(PhysicsWorld, model, mass) {
  
  const box = new THREE.Box3().setFromObject(model);
  
  const { max, min } = box
  
  const center = new THREE.Vector3();
  
  box.getCenter(center);
  
  const body = new CANNON.Body({
  
  mass: mass,
  
  shape: new CANNON.Box(new CANNON.Vec3((max.x - min.x) / 2, (max.y - min.y) / 2, (max.z - min.z) / 2)),
  
  position: center,
  
  })
  
  body.position.copy(model.position)
  
  PhysicsWorld.addBody(body)
  
  body.render = () => model.position.copy(body.position)
  
  }
  

  完整源码：GitHub

  小结

  • 本文提供 物理cannon使用 完整 Three.js 源码与在线 Demo，建议先运行案例再改 uniform/参数做二次实验
  • 更多 Three.js 实战案例见 three-cesium-examples 合集 与 GitHub 开源仓库