标签：function web canvas 特效 ctx 酷炫 radius Math dot
<!doctype html><html lang="en"><head>
<meta charset="gbk2312">
<title>粒子背景</title>
<link rel="stylesheet" type="text/css" href="style.css" media="all">
<style>
html,
body {
font-size: 14px;
font-family: "微软雅黑", Helvetica, Tahoma, Arial, sans-serif;
color: #000;
background-color: #30333F;
margin: 0;
padding: 0;
}
img {
border: 0;
}
.cf:before,
.cf:after {
display: table;
content: "";
}
.cf:after {
clear: both;
}
.cf {
*zoom: 1;
}
canvas {
position: fixed;
top: 0px;
}
</style></head><body id="login-page">
<canvas width="1293" height="717"></canvas>
<script>
/**
* Created by Administrator on 2016/6/29.
*/
var canvas = document.querySelector('canvas'),
ctx = canvas.getContext('2d')
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
ctx.lineWidth = .3;
ctx.strokeStyle = (new Color(150)).style;
var mousePosition = {
x: 30 * canvas.width / 100,
y: 30 * canvas.height / 100
};
var dots = {
nb: 750,
distance: 50,
d_radius: 100,
array: []
};
function colorValue(min) {
return Math.floor(Math.random() * 255 + min);
}
function createColorStyle(r, g, b) {
return 'rgba(' + r + ',' + g + ',' + b + ', 0.8)';
}
function mixComponents(comp1, weight1, comp2, weight2) {
return (comp1 * weight1 + comp2 * weight2) / (weight1 + weight2);
}
function averageColorStyles(dot1, dot2) {
var color1 = dot1.color,
color2 = dot2.color;
var r = mixComponents(color1.r, dot1.radius, color2.r, dot2.radius),
g = mixComponents(color1.g, dot1.radius, color2.g, dot2.radius),
b = mixComponents(color1.b, dot1.radius, color2.b, dot2.radius);
return createColorStyle(Math.floor(r), Math.floor(g), Math.floor(b));
}
function Color(min) {
min = min || 0;
this.r = colorValue(min);
this.g = colorValue(min);
this.b = colorValue(min);
this.style = createColorStyle(this.r, this.g, this.b);
}
function Dot() {
this.x = Math.random() * canvas.width;
this.y = Math.random() * canvas.height;
this.vx = -.5 + Math.random();
this.vy = -.5 + Math.random();
this.radius = Math.random() * 2;
this.color = new Color();
}
Dot.prototype = {
draw: function () {
ctx.beginPath();
ctx.fillStyle = this.color.style;
ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, false);
ctx.fill();
}
};
function createDots() {
for (i = 0; i < dots.nb; i++) {
dots.array.push(new Dot());
}
}
function moveDots() {
for (i = 0; i < dots.nb; i++) {
var dot = dots.array[i];
if (dot.y < 0 || dot.y > canvas.height) {
dot.vx = dot.vx;
dot.vy = - dot.vy;
}
else if (dot.x < 0 || dot.x > canvas.width) {
dot.vx = - dot.vx;
dot.vy = dot.vy;
}
dot.x += dot.vx;
dot.y += dot.vy;
}
}
function connectDots() {
for (i = 0; i < dots.nb; i++) {
for (j = i; j < dots.nb; j++) {
i_dot = dots.array[i];
j_dot = dots.array[j];
if ((i_dot.x - j_dot.x) < dots.distance && (i_dot.y - j_dot.y) < dots.distance && (i_dot.x - j_dot.x) > - dots.distance && (i_dot.y - j_dot.y) > - dots.distance) {
if ((i_dot.x - mousePosition.x) < dots.d_radius && (i_dot.y - mousePosition.y) < dots.d_radius && (i_dot.x - mousePosition.x) > - dots.d_radius && (i_dot.y - mousePosition.y) > - dots.d_radius) {
ctx.beginPath();
ctx.strokeStyle = averageColorStyles(i_dot, j_dot);
ctx.moveTo(i_dot.x, i_dot.y);
ctx.lineTo(j_dot.x, j_dot.y);
ctx.stroke();
ctx.closePath();
}
}
}
}
}
function drawDots() {
for (i = 0; i < dots.nb; i++) {
var dot = dots.array[i];
dot.draw();
}
}
function animateDots() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
moveDots();
connectDots();
drawDots();
requestAnimationFrame(animateDots);
}
document.querySelector('canvas').addEventListener('mousemove', function (e) {
mousePosition.x = e.pageX;
mousePosition.y = e.pageY;
})
document.querySelector('canvas').addEventListener('mouseleave', function (e) {
mousePosition.x = canvas.width / 2;
mousePosition.y = canvas.height / 2;
})
createDots();
requestAnimationFrame(animateDots);
</script></body></html>标签：function,web,canvas,特效,ctx,酷炫,radius,Math,dot 来源： https://blog.51cto.com/u_15262460/2883076
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