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jq22-code3.html
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<!DOCTYPE html>
<!-- saved from url=(0030)http://www.jq22.com/js/a3.html -->
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>jq22-code3</title>
<style>
body {
background: #000;
overflow: hidden;
}
canvas {
display: block;
}
</style>
</head>
<body>
<canvas id="canvas" width="1440" height="754"></canvas>
<script>
var canvas,
ctx,
width,
height,
size,
lines,
tick;
function line() {
this.path = [];
this.speed = rand(10, 20);
this.count = randInt(10, 30);
this.x = width / 2, +1;
this.y = height / 2 + 1;
this.target = {
x: width / 2,
y: height / 2
};
this.dist = 0;
this.angle = 0;
this.hue = tick / 5;
this.life = 1;
this.updateAngle();
this.updateDist();
}
line.prototype.step = function(i) {
this.x += Math.cos(this.angle) * this.speed;
this.y += Math.sin(this.angle) * this.speed;
this.updateDist();
if (this.dist < this.speed) {
this.x = this.target.x;
this.y = this.target.y;
this.changeTarget();
}
this.path.push({
x: this.x,
y: this.y
});
if (this.path.length > this.count) {
this.path.shift();
}
this.life -= 0.001;
if (this.life <= 0) {
this.path = null;
lines.splice(i, 1);
}
};
line.prototype.updateDist = function() {
var dx = this.target.x - this.x,
dy = this.target.y - this.y;
this.dist = Math.sqrt(dx * dx + dy * dy);
}
line.prototype.updateAngle = function() {
var dx = this.target.x - this.x,
dy = this.target.y - this.y;
this.angle = Math.atan2(dy, dx);
}
line.prototype.changeTarget = function() {
var randStart = randInt(0, 3);
switch (randStart) {
case 0: // up
this.target.y = this.y - size;
break;
case 1: // right
this.target.x = this.x + size;
break;
case 2: // down
this.target.y = this.y + size;
break;
case 3: // left
this.target.x = this.x - size;
}
this.updateAngle();
};
line.prototype.draw = function(i) {
ctx.beginPath();
var rando = rand(0, 10);
for (var j = 0, length = this.path.length; j < length; j++) {
ctx[(j === 0) ? 'moveTo' : 'lineTo'](this.path[j].x + rand(-rando, rando), this.path[j].y + rand(-rando, rando));
}
ctx.strokeStyle = 'hsla(' + rand(this.hue, this.hue + 30) + ', 80%, 55%, ' + (this.life / 3) + ')';
ctx.lineWidth = rand(0.1, 2);
ctx.stroke();
};
function rand(min, max) {
return Math.random() * (max - min) + min;
}
function randInt(min, max) {
return Math.floor(min + Math.random() * (max - min + 1));
};
function init() {
canvas = document.getElementById('canvas');
ctx = canvas.getContext('2d');
size = 30;
lines = [];
reset();
loop();
}
function reset() {
width = Math.ceil(window.innerWidth / 2) * 2;
height = Math.ceil(window.innerHeight / 2) * 2;
tick = 0;
lines.length = 0;
canvas.width = width;
canvas.height = height;
}
function create() {
if (tick % 10 === 0) {
lines.push(new line());
}
}
function step() {
var i = lines.length;
while (i--) {
lines[i].step(i);
}
}
function clear() {
ctx.globalCompositeOperation = 'destination-out';
ctx.fillStyle = 'hsla(0, 0%, 0%, 0.1';
ctx.fillRect(0, 0, width, height);
ctx.globalCompositeOperation = 'lighter';
}
function draw() {
ctx.save();
ctx.translate(width / 2, height / 2);
ctx.rotate(tick * 0.001);
var scale = 0.8 + Math.cos(tick * 0.02) * 0.2;
ctx.scale(scale, scale);
ctx.translate(-width / 2, -height / 2);
var i = lines.length;
while (i--) {
lines[i].draw(i);
}
ctx.restore();
}
function loop() {
requestAnimationFrame(loop);
create();
step();
clear();
draw();
tick++;
}
function onresize() {
reset();
}
window.addEventListener('resize', onresize);
init();
</script>
</body></html>