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代码片段 1
<!DOCTYPE html>
<html>
<head>
<meta charset=”utf-8″>
<title>particle nets</title>
<style>
html,
body {
margin: 0;
padding: 0;
height: 100%;
overflow: hidden;
}
</style>
</head>
<body>
<canvas id=”cas”></canvas>
<script>
var canvas = document.getElementById(“cas”),
ctx = canvas.getContext(“2d”);
function resize() {
canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
console.log(“canvasWidth:” + canvas.width, “canvasHeight:” + canvas.height);
}
resize();
window.onresize = resize;
var RAF = (function () {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.setTimeout(callback, 1000 / 60);
})();
var warea = { x: null, y: null, max: 20000 };
window.onmousemove = function (e) {
e = e || event;
warea.x = e.clientX;
warea.y = e.clientY;
};
window.onmouseout = function (e) {
e = e || event;
warea.x = null;
warea.y = null;
}
var dots = [];
for (var i = 0; i < 300; i++) {
var x = Math.random() * canvas.width,
y = Math.random() * canvas.height;
var xa = Math.random() * 2 – 1,
ya = Math.random() * 2 – 1;
dots.push({ “x”: x, “y”: y, “xa”: xa, “ya”: ya, “max”: 6000 });
}
setTimeout(function () { animate(); }, 100);
function animate() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
var ndots = [warea].concat(dots);
dots.forEach(function (dot) {
dot.x += dot.xa;
dot.y += dot.ya;
dot.xa *= (dot.x > canvas.width || dot.x < 0) ? -1 : 1;
dot.ya *= (dot.y > canvas.height || dot.y < 0) ? -1 : 1;
ctx.fillRect(dot.x – .5, dot.y – .5, 1, 1);
for (var i = 0; i < ndots.length; i++) {
var d2 = ndots[i];
if (dot === d2 || d2.x === null || d2.y === null) continue;
var xc = dot.x – d2.x,
yc = dot.y – d2.y;
var dis = xc * xc + yc * yc;
var ratio;
if (dis < d2.max) {
if (d2 === warea && dis > (d2.max / 2)) {
dot.x -= xc * 0.03;
dot.y -= yc * 0.03;
}
ratio = (d2.max – dis) / d2.max;
ctx.beginPath();
ctx.lineWidth = ratio / 2;
ctx.strokeStyle = “rgba(0,0,0,” + (ratio + .2) + “)”;
ctx.moveTo(dot.x, dot.y);
ctx.lineTo(d2.x, d2.y);
ctx.stroke();
}
}
ndots.splice(ndots.indexOf(dot), 1);
});
RAF(animate);
}
</script>
</body>
</html>
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