3.js - 自由落体（物理引擎）

球会在原点，自由落体运动，落到下面去，没法做成gif，所以截了两张图

import * as THREE from 'three'
import gsap from 'gsap' // 导入动画库
import * as dat from 'dat.gui' // 导入dat.gui`导入 cannon-es 引擎`
import * as CANNON from 'cannon-es'// --------------------------------------------------------------------------------const scene = new THREE.Scene()const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 300)
camera.position.set(0, 0, 18)
scene.add(camera)// 渲染器透明
const renderer = new THREE.WebGLRenderer({ alpha: true })
renderer.setSize(window.innerWidth, window.innerHeight)
renderer.shadowMap.enabled = true
// @ts-ignore
renderer.physicallyCorrectLights = true
document.body.appendChild(renderer.domElement)// -------------------------------------------------------------------------------// 创建球
const sphereGeometry = new THREE.SphereGeometry(1, 20, 20)
const sphereMaterial = new THREE.MeshPhysicalMaterial()
const sphere = new THREE.Mesh(sphereGeometry, sphereMaterial)
sphere.castShadow = true `投射自己的阴影`
scene.add(sphere)// 创建平面
const floor = new THREE.Mesh(new THREE.PlaneGeometry(20, 20), new THREE.MeshStandardMaterial())
floor.position.set(0, -5, 0)
floor.rotation.x = -Math.PI / 2
floor.receiveShadow = true `接受别的物体的阴影`
scene.add(floor)`创建物理世界`
const world = new CANNON.World()
world.gravity.set(0, -9.8, 0)`创建 - 物理小球形状`
const sphereShape = new CANNON.Sphere(1)
`设置物体材质`
const sphereWorldMaterial = new CANNON.Material()
`创建物理世界的物体`
const sphereBody = new CANNON.Body({shape: sphereShape,position: new CANNON.Vec3(0, 0, 0),mass: 1, `小球质量`material: sphereWorldMaterial `物体材质`
})`将 sphereBody 添加到物理世界`
world.addBody(sphereBody)// 环境光
const ambientLight = new THREE.AmbientLight(0xffffff, 0.5)
scene.add(ambientLight)// 平行光
const directionalLight = new THREE.DirectionalLight(0xffffff, 0.5)
directionalLight.castShadow = true
directionalLight.position.set(0, 8, 0) // 平行光的位置
scene.add(directionalLight)
// 平行光辅助器
const directionalLightHelp = new THREE.DirectionalLightHelper(directionalLight)
scene.add(directionalLightHelp)// -------------------------------------------------------------------------------const axesHelper = new THREE.AxesHelper(8)
scene.add(axesHelper)const clock = new THREE.Clock()const render = () => {// getDelta()：返回，距离上次调用，getDelta()，以来经过的秒数let deltaTime = clock.getDelta()`world.step()：更新物理引擎里的世界物体参数一：指定了，物理引擎内部模拟的时间步长（以秒为单位），在这里，设置为，大约每1/120秒更新一次物理世界，参数二：实际的时间差，它允许物理引擎根据实际的帧率调整其模拟，以保持物理行为的稳定性、一致性，`world.step(1/120, deltaTime)`将，物理引擎的sphereBody的位置，复制给，渲染引擎的sphere`sphere.position.copy(sphereBody.position)renderer.render(scene, camera)requestAnimationFrame(render)
}
render()window.addEventListener('resize', () => {// 重置相机的宽高比camera.aspect = window.innerWidth / window.innerHeight// 更新相机的投影矩阵camera.updateProjectionMatrix()// 重置渲染器的宽高比renderer.setSize(window.innerWidth, window.innerHeight)// 更新渲染器的像素比renderer.setPixelRatio(window.devicePixelRatio)
})