今天想一个JS小应用，用canvas结合Javascript实现酷炫动态背景，鼠标滑动背景跟着动。这种效果在一些专题页面中经常会用到，所以今天在这里分享给大家，参考参考咯。我们先看下效果图：
有点像繁星点点的感觉啊，废话不多说，直接上代码吧。核心JS代码如何：
window.onload = function () {
//定义body的margin由默认值8px->0px
document.body.style.margin = "0";
document.body.style.background = "#30333F";
//创建canvas画布
document.body.appendChild(document.createElement('canvas'));
var canvas = document.querySelector('canvas'),
ctx = canvas.getContext('2d') //ctx返回一个在canvas上画图的api/dom
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
canvas.style.position = 'fixed';
ctx.lineWidth = .3;
ctx.strokeStyle = (new Color(150)).style;
//定义鼠标覆盖范围
var mousePosition = {
x: 30 * canvas.width / 100,
y: 30 * canvas.height / 100
};
var dots = {
nb: 1000,//Dot的总数
distance: 50,
d_radius: 100,
array: []
};
//创建颜色类，Color类返回字符串型rgba（*,*,*,.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 colorValue(min) {
return Math.floor(Math.random() * 255 + min);
}
function createColorStyle(r, g, b) {
return 'rgba(' + r + ',' + g + ',' + b + ', 0.8)';
}
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);
}
//创建Dot类以及一系列方法
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 moveDots() {//Dot对象的移动
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() {//DOt对象的连接
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();//绘制定义的路线
ctx.closePath();//创建从当前点回到起始点的路径
}
}
}
}
}
function createDots() {//创建nb个Dot对象
for (i = 0; i < dots.nb; i++) {
dots.array.push(new Dot());
}
}
function drawDots() {//引用Dot原型链，使用draw方法，在canvas上画出Dot对象
for (i = 0; i < dots.nb; i++) {
var dot = dots.array[i];
dot.draw();
}
}
function animateDots() {
ctx.clearRect(0, 0, canvas.width, canvas.height);//清除画布，否则线条会连在一起
moveDots();
connectDots();
drawDots();
requestAnimationFrame(animateDots);
}
createDots();//使用创建Dot类函数
requestAnimationFrame(animateDots);//使用canvas独有的60Hz刷新屏幕画布的方法
document.querySelector('canvas').addEventListener('mousemove', function (e) {
mousePosition.x = e.pageX;
mousePosition.y = e.pageY;
})
document.querySelector('canvas').addEventListener('mouseleave', function (e) {//鼠标离开时，连接自动返回到画布中心
mousePosition.x = canvas.width / 2;
mousePosition.y = canvas.height / 2;
})
}完整的DEMO如下：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>JS小应用：酷炫动态背景，鼠标滑动背景跟着动 | Web前端之家www.jiangweishan.com</title>
</head>
<body>
<script>
window.onload = function () {
//定义body的margin由默认值8px->0px
document.body.style.margin = "0";
document.body.style.background = "#30333F";
//创建canvas画布
document.body.appendChild(document.createElement('canvas'));
var canvas = document.querySelector('canvas'),
ctx = canvas.getContext('2d') //ctx返回一个在canvas上画图的api/dom
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
canvas.style.position = 'fixed';
ctx.lineWidth = .3;
ctx.strokeStyle = (new Color(150)).style;
//定义鼠标覆盖范围
var mousePosition = {
x: 30 * canvas.width / 100,
y: 30 * canvas.height / 100
};
var dots = {
nb: 1000,//Dot的总数
distance: 50,
d_radius: 100,
array: []
};
//创建颜色类，Color类返回字符串型rgba（*,*,*,.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 colorValue(min) {
return Math.floor(Math.random() * 255 + min);
}
function createColorStyle(r, g, b) {
return 'rgba(' + r + ',' + g + ',' + b + ', 0.8)';
}
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);
}
//创建Dot类以及一系列方法
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 moveDots() {//Dot对象的移动
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() {//DOt对象的连接
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();//绘制定义的路线
ctx.closePath();//创建从当前点回到起始点的路径
}
}
}
}
}
function createDots() {//创建nb个Dot对象
for (i = 0; i < dots.nb; i++) {
dots.array.push(new Dot());
}
}
function drawDots() {//引用Dot原型链，使用draw方法，在canvas上画出Dot对象
for (i = 0; i < dots.nb; i++) {
var dot = dots.array[i];
dot.draw();
}
}
function animateDots() {
ctx.clearRect(0, 0, canvas.width, canvas.height);//清除画布，否则线条会连在一起
moveDots();
connectDots();
drawDots();
requestAnimationFrame(animateDots);
}
createDots();//使用创建Dot类函数
requestAnimationFrame(animateDots);//使用canvas独有的60Hz刷新屏幕画布的方法
document.querySelector('canvas').addEventListener('mousemove', function (e) {
mousePosition.x = e.pageX;
mousePosition.y = e.pageY;
})
document.querySelector('canvas').addEventListener('mouseleave', function (e) {//鼠标离开时，连接自动返回到画布中心
mousePosition.x = canvas.width / 2;
mousePosition.y = canvas.height / 2;
})
}
</script>
</body>
</html>
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