先看效果：
再看代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>机器人跳舞</title>
<style>
body, html {
position: absolute;
margin: 0;
padding: 0;
width: 100%;
height: 100%;
overflow: hidden;
}
canvas {
position: absolute;
width: 100%;
height: 100%;
background:#000;
cursor: pointer;
}
</style>
</head>
<body>
<canvas></canvas>
</body>
<script>
"use strict";
/工作线程代码///
const theLastExperience = noWorkers => {
"use strict";
// ---- 机器人结构 ----
const struct = {
points: [
{
x: 0,
y: -4,
f(s, d) {
this.y -= 0.01 * s * ts;
}
},
{
x: 0,
y: -16,
f(s, d) {
this.y -= 0.02 * s * d * ts;
}
},
{
x: 0,
y: 12,
f(s, d) {
this.y += 0.02 * s * d * ts;
}
},
{ x: -12, y: 0 },
{ x: 12, y: 0 },
{
x: -3,
y: 34,
f(s, d) {
if (d > 0) {
this.x += 0.01 * s * ts;
this.y -= 0.015 * s * ts;
} else {
this.y += 0.02 * s * ts;
}
}
},
{
x: 3,
y: 34,
f(s, d) {
if (d > 0) {
this.y += 0.02 * s * ts;
} else {
this.x -= 0.01 * s * ts;
this.y -= 0.015 * s * ts;
}
}
},
{
x: -28,
y: 0,
f(s, d) {
this.x += this.vx * 0.025 * ts;
this.y -= 0.001 * s * ts;
}
},
{
x: 28,
y: 0,
f(s, d) {
this.x += this.vx * 0.025 * ts;
this.y -= 0.001 * s * ts;
}
},
{
x: -3,
y: 64,
f(s, d) {
this.y += 0.015 * s * ts;
if (d > 0) {
this.y -= 0.01 * s * ts;
} else {
this.y += 0.05 * s * ts;
}
}
},
{
x: 3,
y: 64,
f(s, d) {
this.y += 0.015 * s * ts;
if (d > 0) {
this.y += 0.05 * s * ts;
} else {
this.y -= 0.01 * s * ts;
}
}
}
],
links: [
{ p0: 3, p1: 7, size: 12, lum: 0.5 },
{ p0: 1, p1: 3, size: 24, lum: 0.5 },
{ p0: 1, p1: 0, size: 60, lum: 0.5, disk: 1 },
{ p0: 5, p1: 9, size: 16, lum: 0.5 },
{ p0: 2, p1: 5, size: 32, lum: 0.5 },
{ p0: 1, p1: 2, size: 50, lum: 1 },
{ p0: 6, p1: 10, size: 16, lum: 1.5 },
{ p0: 2, p1: 6, size: 32, lum: 1.5 },
{ p0: 4, p1: 8, size: 12, lum: 1.5 },
{ p0: 1, p1: 4, size: 24, lum: 1.5 }
]
};
class Robot {
constructor(color, light, size, x, y, struct) {
this.x = x;
this.points = [];
this.links = [];
this.frame = 0;
this.dir = 1;
this.size = size;
this.color = Math.round(color);
this.light = light;
// ---- 创建点 ----
for (const p of struct.points) {
this.points.push(new Robot.Point(size * p.x + x, size * p.y + y, p.f));
}
// ---- 创建链接 ----
for (const link of struct.links) {
const p0 = this.points[link.p0];
const p1 = this.points[link.p1];
const dx = p0.x - p1.x;
const dy = p0.y - p1.y;
this.links.push(
new Robot.Link(
this,
p0,
p1,
Math.sqrt(dx * dx + dy * dy),
link.size * size / 3,
link.lum,
link.force,
link.disk
)
);
}
}
update() {
if (++this.frame % Math.round(20 / ts) === 0) this.dir = -this.dir;
if (this === pointer.dancerDrag && this.size < 16 && this.frame > 600) {
pointer.dancerDrag = null;
dancers.push(
new Robot(
this.color + 90,
this.light * 1.25,
this.size * 2,
pointer.x,
pointer.y - 100 * this.size * 2,
struct
)
);
dancers.sort(function(d0, d1) {
return d0.size - d1.size;
});
}
// ---- 更新链接 ----
for (const link of this.links) link.update();
// ---- 更新点----
for (const point of this.points) point.update(this);
for (const link of this.links) {
const p1 = link.p1;
if (p1.y > canvas.height * ground - link.size * 0.5) {
p1.y = canvas.height * ground - link.size * 0.5;
p1.x -= p1.vx;
p1.vx = 0;
p1.vy = 0;
}
}
// ---- 中心位置 ----
this.points[3].x += (this.x - this.points[3].x) * 0.001;
}
draw() {
for (const link of this.links) {
if (link.size) {
const dx = link.p1.x - link.p0.x;
const dy = link.p1.y - link.p0.y;
const a = Math.atan2(dy, dx);
// ---- 阴影 ----
ctx.save();
ctx.translate(link.p0.x + link.size * 0.25, link.p0.y + link.size * 0.25);
ctx.rotate(a);
ctx.drawImage(
link.shadow,
-link.size * 0.5,
-link.size * 0.5
);
ctx.restore();
ctx.save();
ctx.translate(link.p0.x, link.p0.y);
ctx.rotate(a);
ctx.drawImage(
link.image,
-link.size * 0.5,
-link.size * 0.5
);
ctx.restore();
}
}
}
}
Robot.Link = class Link {
constructor(parent, p0, p1, dist, size, light, force, disk) {
this.p0 = p0;
this.p1 = p1;
this.distance = dist;
this.size = size;
this.light = light || 1.0;
this.force = force || 0.5;
this.image = this.stroke(
"hsl(" + parent.color + " ,30%, " + parent.light * this.light + "%)",
true, disk, dist, size
);
this.shadow = this.stroke("rgba(0,0,0,0.5)", false, disk, dist, size);
}
update() {
const p0 = this.p0;
const p1 = this.p1;
const dx = p1.x - p0.x;
const dy = p1.y - p0.y;
const dist = Math.sqrt(dx * dx + dy * dy);
if (dist > 0.0) {
const tw = p0.w + p1.w;
const r1 = p1.w / tw;
const r0 = p0.w / tw;
const dz = (this.distance - dist) * this.force;
const sx = dx / dist * dz;
const sy = dy / dist * dz;
p1.x += sx * r0;
p1.y += sy * r0;
p0.x -= sx * r1;
p0.y -= sy * r1;
}
}
stroke(color, axis, disk, dist, size) {
let image;
if (noWorkers) {
image = document.createElement("canvas");
image.width = dist + size;
image.height = size;
} else {
image = new OffscreenCanvas(dist + size, size);
}
const ict = image.getContext("2d");
ict.beginPath();
ict.lineCap = "round";
ict.lineWidth = size;
ict.strokeStyle = color;
if (disk) {
ict.arc(size * 0.5 + dist, size * 0.5, size * 0.5, 0, 2 * Math.PI);
ict.fillStyle = color;
ict.fill();
} else {
ict.moveTo(size * 0.5, size * 0.5);
ict.lineTo(size * 0.5 + dist, size * 0.5);
ict.stroke();
}
if (axis) {
const s = size / 10;
ict.fillStyle = "#000";
ict.fillRect(size * 0.5 - s, size * 0.5 - s, s * 2, s * 2);
ict.fillRect(size * 0.5 - s + dist, size * 0.5 - s, s * 2, s * 2);
}
return image;
}
};
Robot.Point = class Point {
constructor(x, y, fn, w) {
this.x = x;
this.y = y;
this.w = w || 0.5;
this.fn = fn || null;
this.px = x;
this.py = y;
this.vx = 0.0;
this.vy = 0.0;
}
update(robot) {
// ---- 拖拉 ----
if (robot === pointer.dancerDrag && this === pointer.pointDrag) {
this.x += (pointer.x - this.x) * 0.1;
this.y += (pointer.y - this.y) * 0.1;
}
// ---- 跳舞 ----
if (robot !== pointer.dancerDrag) {
this.fn && this.fn(16 * Math.sqrt(robot.size), robot.dir);
}
this.vx = this.x - this.px;
this.vy = this.y - this.py;
this.px = this.x;
this.py = this.y;
this.vx *= 0.995;
this.vy *= 0.995;
this.x += this.vx;
this.y += this.vy + 0.01 * ts;
}
};
// ---- 初始化 ----
const dancers = [];
let ground = 1.0;
let canvas = { width: 0, height: 0, resize: true };
let ctx = null;
let pointer = { x: 0, y: 0, dancerDrag: null, pointDrag: null };
let ts = 1;
let lastTime = 0;
// ---- 来自主线程的消息 ----
const message = e => {
switch (e.data.msg) {
case "start":
canvas.elem = e.data.elem;
canvas.width = canvas.elem.width;
canvas.height = canvas.elem.height;
ctx = canvas.elem.getContext("2d");
initRobots();
requestAnimationFrame(run);
break;
case "resize":
canvas.width = e.data.width;
canvas.height = e.data.height;
canvas.resize = true;
break;
case "pointerMove":
pointer.x = e.data.x;
pointer.y = e.data.y;
break;
case "pointerDown":
pointer.x = e.data.x;
pointer.y = e.data.y;
for (const dancer of dancers) {
for (const point of dancer.points) {
const dx = pointer.x - point.x;
const dy = pointer.y - point.y;
const d = Math.sqrt(dx * dx + dy * dy);
if (d < 60) {
pointer.dancerDrag = dancer;
pointer.pointDrag = point;
dancer.frame = 0;
}
}
}
break;
case "pointerUp":
pointer.dancerDrag = null;
break;
}
};
// ----调整屏幕大小----
const resize = () => {
canvas.elem.width = canvas.width;
canvas.elem.height = canvas.height;
canvas.resize = false;
ground = canvas.height > 500 ? 0.85 : 1.0;
for (let i = 0; i < dancers.length; i++) {
dancers[i].x = (i + 2) * canvas.width / 9;
}
}
// ---- 主回路 ----
const run = (time) => {
requestAnimationFrame(run);
if (canvas.resize === true) resize();
// ----根据屏幕频率调整速度 ----
if (lastTime !== 0) {
const t = (time - lastTime) / 16;
ts += (t - ts) * 0.1;
if (ts > 1) ts = 1;
}
lastTime = time;
// ---- 清除屏幕 ----
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "#222";
ctx.fillRect(0, 0, canvas.width, canvas.height * 0.15);
ctx.fillRect(0, canvas.height * 0.85, canvas.width, canvas.height * 0.15);
// ---- 动画机器人----
for (const dancer of dancers) {
dancer.update();
dancer.draw();
}
};
const initRobots = () => {
// ---- 启动机器人 ----
ground = canvas.height > 500 ? 0.85 : 1.0;
for (let i = 0; i < 6; i++) {
dancers.push(
new Robot(
i * 360 / 7,
80,
Math.sqrt(Math.min(canvas.width, canvas.height)) / 6,
(i + 2) * canvas.width / 9,
canvas.height * 0.5 - 100,
struct
)
);
}
};
// ---- 主线程与工作线程
if (noWorkers) {
// ---- 模拟postMessage接口 ----
return {
postMessage(data) {
message({ data: data });
}
};
} else {
onmessage = message;
}
};
/ 主线程代码 ///
let worker = null;
const createWorker = fn => {
const URL = window.URL || window.webkitURL;
return new Worker(URL.createObjectURL(new Blob(["(" + fn + ")()"])));
};
// ---- 初始化画布 ----
const canvas = document.querySelector("canvas");
canvas.width = canvas.offsetWidth;
canvas.height = canvas.offsetHeight;
// ---- 实例化工作者 ----
if (window.Worker && window.OffscreenCanvas) {
// 从函数中实例化后台工作程序
worker = createWorker(theLastExperience);
const offscreen = canvas.transferControlToOffscreen();
// 发送数据
worker.postMessage({ msg: "start", elem: offscreen }, [offscreen]);
} else {
// 回退执行到主线程
worker = theLastExperience(true);
worker.postMessage({ msg: "start", elem: canvas });
}
// ---- 调整大小事件 ----
window.addEventListener(
"resize",
() => {
worker.postMessage({
msg: "resize",
width: canvas.offsetWidth,
height: canvas.offsetHeight
});
},
false
);
// ----指针事件 ----
const pointer = {
x: 0,
y: 0,
down(e) {
this.move(e);
worker.postMessage({
msg: "pointerDown",
x: this.x,
y: this.y
});
},
up(e) {
worker.postMessage({
msg: "pointerUp"
});
},
move(e) {
if (e.targetTouches) {
e.preventDefault();
this.x = e.targetTouches[0].clientX;
this.y = e.targetTouches[0].clientY;
} else {
this.x = e.clientX;
this.y = e.clientY;
}
worker.postMessage({
msg: "pointerMove",
x: this.x,
y: this.y
});
}
};
window.addEventListener("mousemove", e => pointer.move(e), false);
canvas.addEventListener("touchmove", e => pointer.move(e), false);
window.addEventListener("mousedown", e => pointer.down(e), false);
window.addEventListener("touchstart", e => pointer.down(e), false);
window.addEventListener("mouseup", e => pointer.up(e), false);
window.addEventListener("touchend", e => pointer.up(e), false);
</script>
</html>
