<!DOCTYPE html>
<html lang="en" >
<head>
<title>Code The World - Electric strings</title>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<script>
window.requestAnimFrame = (function() {
return (
window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) { window.setTimeout(callback); }
);
});
function init(elem_id) {
let canvas = document.getElementById(elem_id),
c = canvas.getContext("2d"),
w = (canvas.width = window.innerWidth),
h = (canvas.height = window.innerHeight);
c.fillStyle = "rgba(30,30,30,1)";
c.fillRect(0, 0, w, h);
return {c:c, canvas:canvas};
}
</script>
<!-- 引入外部css文件 -->
<link rel="stylesheet" type="text/css" href="./style.css">
</head>
<body>
<canvas id="canvas"></canvas>
<!-- 引入外部JavaScript文件 -->
<script type="text/javascript" src="./script.js"></script>
</body>
</html>
body, html {
margin: 0 px;
padding: 0 px;
position: fixed;
background: rgb(30,30,30);
}
window.onload = function() {
let c = init("canvas").c,
canvas = init("canvas").canvas,
w = (canvas.width = window.innerWidth),
h = (canvas.height = window.innerHeight),
mouse = { x: false, y: false },
last_mouse = {};
// initiation
function dist(p1x, p1y, p2x, p2y) {
return Math.sqrt(Math.pow(p2x - p1x, 2) + Math.pow(p2y - p1y, 2));
}
class segment {
constructor(parent, l, a, first) {
this.first = first;
if (first) {
this.pos = {
x: parent.x,
y: parent.y
};
} else {
this.pos = {
x: parent.nextPos.x,
y: parent.nextPos.y
};
}
this.l = l;
this.ang = a;
this.nextPos = {
x: this.pos.x + this.l * Math.cos(this.ang),
y: this.pos.y + this.l * Math.sin(this.ang)
};
}
update(t) {
this.ang = Math.atan2(t.y - this.pos.y, t.x - this.pos.x);
this.pos.x = t.x + this.l * Math.cos(this.ang - Math.PI);
this.pos.y = t.y + this.l * Math.sin(this.ang - Math.PI);
this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang);
this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang);
}
fallback(t) {
this.pos.x = t.x;
this.pos.y = t.y;
this.nextPos.x = this.pos.x + this.l * Math.cos(this.ang);
this.nextPos.y = this.pos.y + this.l * Math.sin(this.ang);
}
show() {
c.lineTo(this.nextPos.x, this.nextPos.y);
}
}
class tentacle {
constructor(x, y, l, n, a) {
this.x = x;
this.y = y;
this.l = l;
this.n = n;
this.t = {};
this.rand = Math.random();
this.segments = [new segment(this, this.l / this.n, 0, true)];
for (let i = 1; i < this.n; i++) {
this.segments.push(
new segment(this.segments[i - 1], this.l / this.n, 0, false)
);
}
}
move(last_target, target) {
this.angle = Math.atan2(target.y - this.y,target.x - this.x);
this.dt = dist(last_target.x, last_target.y, target.x, target.y) + 5;
this.t = {
x: target.x - 0.8 * this.dt * Math.cos(this.angle),
y: target.y - 0.8 * this.dt * Math.sin(this.angle)
};
if (this.t.x) {
this.segments[this.n - 1].update(this.t);
} else {
this.segments[this.n - 1].update(target);
}
for (let i = this.n - 2; i >= 0; i--) {
this.segments[i].update(this.segments[i + 1].pos);
}
if (
dist(this.x, this.y, target.x, target.y) <=
this.l + dist(last_target.x, last_target.y, target.x, target.y)
) {
this.segments[0].fallback({ x: this.x, y: this.y });
for (let i = 1; i < this.n; i++) {
this.segments[i].fallback(this.segments[i - 1].nextPos);
}
}
}
show(target) {
if (dist(this.x, this.y, target.x, target.y) <= this.l) {
c.globalCompositeOperation = "color-dodge";
c.beginPath();
c.lineTo(this.x, this.y);
for (let i = 0; i < this.n; i++) {
this.segments[i].show();
}
c.strokeStyle = "hsl("+(this.rand * 60 + 180)+",100%," + (this.rand * 60 + 25) + "%)";
c.lineWidth = this.rand * 2;
c.lineCap = "round";
c.lineJoin = "round";
c.stroke();
c.globalCompositeOperation = "source-over";
}
}
show2(target) {
c.beginPath();
if (dist(this.x, this.y, target.x, target.y) <= this.l) {
c.arc(this.x, this.y, 2 * this.rand + 1, 0, 2 * Math.PI);
c.fillStyle = "white";
} else {
c.arc(this.x, this.y, this.rand * 2, 0, 2 * Math.PI);
c.fillStyle = "darkcyan";
}
c.fill();
}
}
let maxl = 300,
minl = 50,
n = 30,
numt = 500, // 特性点的个数 500
tent = [],
clicked = false,
target = { x: 0, y: 0 },
last_target = {},
t = 0,
q = 10;
for (let i = 0; i < numt; i++) {
tent.push(
new tentacle(
Math.random() * w,
Math.random() * h,
Math.random() * (maxl - minl) + minl,
n,
Math.random() * 2 * Math.PI
)
);
}
function draw() {
//animation
if (mouse.x) {
target.errx = mouse.x - target.x;
target.erry = mouse.y - target.y;
} else {
target.errx = w / 2 + (h / 2 - q) * Math.sqrt(2) * Math.cos(t) / (Math.pow(Math.sin(t), 2) + 1) - target.x;
target.erry = h / 2 + (h / 2 - q) * Math.sqrt(2) * Math.cos(t) * Math.sin(t) / (Math.pow(Math.sin(t), 2) + 1) - target.y;
}
target.x += target.errx / 10;
target.y += target.erry / 10;
t += 0.01;
c.beginPath();
c.arc(target.x, target.y, dist(last_target.x, last_target.y, target.x, target.y)+5, 0, 2 * Math.PI);
c.fillStyle = "hsl(210,100%,80%)";
c.fill();
for (i = 0; i < numt; i++) {
tent[i].move(last_target, target);
tent[i].show2(target);
}
for (i = 0; i < numt; i++) {
tent[i].show(target);
}
last_target.x = target.x;
last_target.y = target.y;
}
canvas.addEventListener(
"mousemove",
function(e) {
last_mouse.x = mouse.x;
last_mouse.y = mouse.y;
mouse.x = e.pageX - this.offsetLeft;
mouse.y = e.pageY - this.offsetTop;
}, false
);
canvas.addEventListener("mouseleave", function(e) { mouse.x = false; mouse.y = false; });
canvas.addEventListener("mousedown", function(e) { clicked = true; }, false);
canvas.addEventListener("mouseup", function(e) { clicked = false; }, false);
function loop() {
window.requestAnimFrame(loop);
// c.fillStyle="rgba(30,30,30,0.1)";
// c.fillRect(0, 0, w, h);
c.clearRect(0, 0, w, h);
draw();
}
window.addEventListener("resize", function() {
(w = canvas.width = window.innerWidth),
(h = canvas.height = window.innerHeight);
loop();
});
loop();
setInterval(loop, 1000 / 60);
};
标签：canvas,ang,target,window,pos,js,001,html,Math From： https://www.cnblogs.com/Hpp918039/p/18596269