先上效果图：
再上代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
html, body, canvas {
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
html, body {
width: 100%;
height: 100%;
overflow: hidden;
margin: 0;
display: flex;
align-items: center;
justify-content: center;
background: #191919;
}
.asset-img {
display: none;
}
</style>
</head>
<body>
<canvas></canvas>
<img class="asset-img" id="light-img" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABkAAAAZCAMAAADzN3VRAAAABGdBTUEA
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BJRU5ErkJggg==" alt="base64">
</body>
<script>
class Mouse {
constructor(canvas) {
this.pos = new Vector(-1000, -1000)
this.radius = 40
canvas.onmousemove = e => this.pos.setXY(e.clientX, e.clientY)
canvas.ontouchmove = e => this.pos.setXY(e.touches[0].clientX, e.touches[0].clientY)
canvas.ontouchcancel = () => this.pos.setXY(-1000, -1000)
canvas.ontouchend = () => this.pos.setXY(-1000, -1000)
}
}
class Dot {
constructor(x, y) {
this.pos = new Vector(x, y)
this.oldPos = new Vector(x, y)
this.friction = 0.97
this.gravity = new Vector(0, 0.6)
this.mass = 1
this.pinned = false
this.lightImg = document.querySelector('#light-img')
this.lightSize = 15
}
update(mouse) {
if (this.pinned) return
let vel = Vector.sub(this.pos, this.oldPos)
this.oldPos.setXY(this.pos.x, this.pos.y)
vel.mult(this.friction)
vel.add(this.gravity)
let { x: dx, y: dy } = Vector.sub(mouse.pos, this.pos)
const dist = Math.sqrt(dx * dx + dy * dy)
const direction = new Vector(dx / dist, dy / dist)
const force = Math.max((mouse.radius - dist) / mouse.radius, 0)
if (force > 0.6) this.pos.setXY(mouse.pos.x, mouse.pos.y)
else {
this.pos.add(vel)
this.pos.add(direction.mult(force))
}
}
drawLight(ctx) {
ctx.drawImage(
this.lightImg,
this.pos.x - this.lightSize / 2, this.pos.y - this.lightSize / 2, this.lightSize, this.lightSize
)
}
draw(ctx) {
ctx.fillStyle = '#aaa'
ctx.fillRect(this.pos.x - this.mass, this.pos.y - this.mass, this.mass * 2, this.mass * 2)
}
}
class Stick {
constructor(p1, p2) {
this.startPoint = p1
this.endPoint = p2
this.length = this.startPoint.pos.dist(this.endPoint.pos)
this.tension = 0.3
}
update() {
const dx = this.endPoint.pos.x - this.startPoint.pos.x
const dy = this.endPoint.pos.y - this.startPoint.pos.y
const dist = Math.sqrt(dx * dx + dy * dy)
const diff = (dist - this.length) / dist
const offsetX = diff * dx * this.tension
const offsetY = diff * dy * this.tension
const m = this.startPoint.mass + this.endPoint.mass
const m1 = this.endPoint.mass / m
const m2 = this.startPoint.mass / m
if (!this.startPoint.pinned) {
this.startPoint.pos.x += offsetX * m1
this.startPoint.pos.y += offsetY * m1
}
if (!this.endPoint.pinned) {
this.endPoint.pos.x -= offsetX * m2
this.endPoint.pos.y -= offsetY * m2
}
}
draw(ctx) {
ctx.beginPath()
ctx.strokeStyle = '#999'
ctx.moveTo(this.startPoint.pos.x, this.startPoint.pos.y)
ctx.lineTo(this.endPoint.pos.x, this.endPoint.pos.y)
ctx.stroke()
ctx.closePath()
}
}
class Rope {
constructor(config) {
this.x = config.x
this.y = config.y
this.segments = config.segments || 10
this.gap = config.gap || 15
this.color = config.color || 'gray'
this.dots = []
this.sticks = []
this.iterations = 10
this.create()
}
pin(index) {
this.dots[index].pinned = true
}
create() {
for (let i = 0; i < this.segments; i++) {
this.dots.push(new Dot(this.x, this.y + i * this.gap))
}
for (let i = 0; i < this.segments - 1; i++) {
this.sticks.push(new Stick(this.dots[i], this.dots[i + 1]))
}
}
update(mouse) {
this.dots.forEach(dot => {
dot.update(mouse)
})
for (let i = 0; i < this.iterations; i++) {
this.sticks.forEach(stick => {
stick.update()
})
}
}
draw(ctx) {
this.dots.forEach(dot => {
dot.draw(ctx)
})
this.sticks.forEach(stick => {
stick.draw(ctx)
})
this.dots[this.dots.length - 1].drawLight(ctx)
}
}
class App {
static width = innerWidth
static height = innerHeight
static dpr = devicePixelRatio > 1 ? 2 : 1
static interval = 1000 / 60
constructor() {
this.canvas = document.querySelector('canvas')
this.ctx = this.canvas.getContext('2d')
this.mouse = new Mouse(this.canvas)
this.resize()
window.addEventListener('resize', this.resize.bind(this))
this.createRopes()
}
createRopes() {
this.ropes = []
const TOTAL = App.width * 0.06
for (let i = 0; i < TOTAL + 1; i++) {
const x = randomNumBetween(App.width * 0.3, App.width * 0.7)
const y = 0
const gap = randomNumBetween(App.height * 0.05, App.height * 0.08)
const segments = 10
const rope = new Rope({ x, y, gap, segments })
rope.pin(0)
this.ropes.push(rope)
}
}
resize() {
App.width = innerWidth
App.height = innerHeight
this.canvas.style.width = '100%'
this.canvas.style.height = '100%'
this.canvas.width = App.width * App.dpr
this.canvas.height = App.height * App.dpr
this.ctx.scale(App.dpr, App.dpr)
this.createRopes()
}
render() {
let now, delta
let then = Date.now()
const frame = () => {
requestAnimationFrame(frame)
now = Date.now()
delta = now - then
if (delta < App.interval) return
then = now - (delta % App.interval)
this.ctx.clearRect(0, 0, App.width, App.height)
// draw here
this.ropes.forEach(rope => {
rope.update(this.mouse)
rope.draw(this.ctx)
})
}
requestAnimationFrame(frame)
}
}
function randomNumBetween(min, max) {
return Math.random() * (max - min) + min
}
window.addEventListener('load', () => {
const app = new App()
app.render()
})
class Vector {
constructor(x, y) {
this.x = x || 0
this.y = y || 0
}
static add(v1, v2) {
return new Vector(v1.x + v2.x, v1.y + v2.y)
}
static sub(v1, v2) {
return new Vector(v1.x - v2.x, v1.y - v2.y)
}
add(x, y) {
if (arguments.length === 1) {
this.x += x.x
this.y += x.y
} else if (arguments.length === 2) {
this.x += x
this.y += y
}
return this
}
sub(x, y) {
if (arguments.length === 1) {
this.x -= x.x
this.y -= x.y
} else if (arguments.length === 2) {
this.x -= x
this.y -= y
}
return this
}
mult(v) {
if (typeof v === 'number') {
this.x *= v
this.y *= v
} else {
this.x *= v.x
this.y *= v.y
}
return this
}
setXY(x, y) {
this.x = x
this.y = y
return this
}
dist(v) {
const dx = this.x - v.x
const dy = this.y - v.y
return Math.sqrt(dx * dx + dy * dy)
}
}
</script>
</html>
代码直接粘贴到html页面就能使用，顺滑的不可言说
