版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/cometwo/article/details/52484908
演示效果：http://www.atool.org/
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script type="text/javascript" src="canvas-nest.js" ></script>
</body>
</html>
! function() {
//封装方法，压缩之后减少文件大小
function get_attribute(node, attr, default_value) {
return node.getAttribute(attr) || default_value;
}
//封装方法，压缩之后减少文件大小
function get_by_tagname(name) {
return document.getElementsByTagName(name);
}
//获取配置参数
function get_config_option() {
var scripts = get_by_tagname("script"),
script_len = scripts.length,
script = scripts[script_len - 1]; //当前加载的script
return {
l: script_len, //长度，用于生成id用
z: get_attribute(script, "zIndex", -1), //z-index
o: get_attribute(script, "opacity", 0.5), //opacity
c: get_attribute(script, "color", "0,0,0"), //color
n: get_attribute(script, "count", 99) //count
};
}
//设置canvas的高宽
function set_canvas_size() {
canvas_width = the_canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth,
canvas_height = the_canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
}
//绘制过程
function draw_canvas() {
context.clearRect(0, 0, canvas_width, canvas_height);
//随机的线条和当前位置联合数组
var e, i, d, x_dist, y_dist, dist; //临时节点
//遍历处理每一个点
random_lines.forEach(function(r, idx) {
r.x += r.xa,
r.y += r.ya, //移动
r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1,
r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1, //碰到边界，反向反弹
context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1); //绘制一个宽高为1的点
//从下一个点开始
for (i = idx + 1; i < all_array.length; i++) {
e = all_array[i];
//不是当前点
if (null !== e.x && null !== e.y) {
x_dist = r.x - e.x, //x轴距离 l
y_dist = r.y - e.y, //y轴距离 n
dist = x_dist * x_dist + y_dist * y_dist; //总距离, m
dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的时候加速
d = (e.max - dist) / e.max,
context.beginPath(),
context.lineWidth = d / 2,
context.strokeStyle = "rgba(" + config.c + "," + (d + 0.2) + ")",
context.moveTo(r.x, r.y),
context.lineTo(e.x, e.y),
context.stroke());
}
}
}), frame_func(draw_canvas);
}
//创建画布，并添加到body中
var the_canvas = document.createElement("canvas"), //画布
config = get_config_option(), //配置
canvas_id = "c_n" + config.l, //canvas id
context = the_canvas.getContext("2d"), canvas_width, canvas_height,
frame_func = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(func) {
window.setTimeout(func, 1000 / 45);
}, random = Math.random,
current_point = {
x: null, //当前鼠标x
y: null, //当前鼠标y
max: 20000
},
all_array;
the_canvas.id = canvas_id;
the_canvas.style.cssText = "position:fixed;top:0;left:0;z-index:" + config.z + ";opacity:" + config.o;
get_by_tagname("body")[0].appendChild(the_canvas);
//初始化画布大小
set_canvas_size(), window.onresize = set_canvas_size;
//当时鼠标位置存储，离开的时候，释放当前位置信息
window.onmousemove = function(e) {
e = e || window.event, current_point.x = e.clientX, current_point.y = e.clientY;
}, window.onmouseout = function() {
current_point.x = null, current_point.y = null;
};
//随机生成config.n条线位置信息
for (var random_lines = [], i = 0; config.n > i; i++) {
var x = random() * canvas_width, //随机位置
y = random() * canvas_height,
xa = 2 * random() - 1, //随机运动方向
ya = 2 * random() - 1;
random_lines.push({
x: x,
y: y,
xa: xa,
ya: ya,
max: 6000 //沾附距离
});
}
all_array = random_lines.concat([current_point]);
//0.1秒后绘制
setTimeout(function() {
draw_canvas();
}, 100);
}();
知乎背景
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>仿知乎背景canvas特效</title>
<meta name="keywords" content="" />
<meta name="description" content="" />
<style type="text/css">
body {
text-align: center;
background: #F7FAFC;
overflow: hidden;
background: #fff;
}
</style>
</head>
<body>
<canvas id="Mycanvas"></canvas>
<script>
//定义画布宽高和生成点的个数
var WIDTH = window.innerWidth,
HEIGHT = window.innerHeight,
POINT = 35;
var canvas = document.getElementById('Mycanvas');
canvas.width = WIDTH,
canvas.height = HEIGHT;
var context = canvas.getContext('2d');
context.strokeStyle = 'rgba(0,0,0,0.2)',
context.strokeWidth = 1,
context.fillStyle = 'rgba(0,0,0,0.1)';
var circleArr = [];
//线条：开始xy坐标，结束xy坐标，线条透明度
function Line(x, y, _x, _y, o) {
this.beginX = x,
this.beginY = y,
this.closeX = _x,
this.closeY = _y,
this.o = o;
}
//点：圆心xy坐标，半径，每帧移动xy的距离
function Circle(x, y, r, moveX, moveY) {
this.x = x,
this.y = y,
this.r = r,
this.moveX = moveX,
this.moveY = moveY;
}
//生成max和min之间的随机数
function num(max, _min) {
var min = arguments[1] || 0;
return Math.floor(Math.random() * (max - min + 1) + min);
}
// 绘制原点
function drawCricle(cxt, x, y, r, moveX, moveY) {
var circle = new Circle(x, y, r, moveX, moveY)
cxt.beginPath()
cxt.arc(circle.x, circle.y, circle.r, 0, 2 * Math.PI)
cxt.closePath()
cxt.fill();
return circle;
}
//绘制线条
function drawLine(cxt, x, y, _x, _y, o) {
var line = new Line(x, y, _x, _y, o)
cxt.beginPath()
cxt.strokeStyle = 'rgba(0,0,0,' + o + ')'
cxt.moveTo(line.beginX, line.beginY)
cxt.lineTo(line.closeX, line.closeY)
cxt.closePath()
cxt.stroke();
}
//每帧绘制
function draw() {
context.clearRect(0, 0, canvas.width, canvas.height);
for(var i = 0; i < POINT; i++) {
drawCricle(context, circleArr[i].x, circleArr[i].y, circleArr[i].r);
}
for(var i = 0; i < POINT; i++) {
for(var j = 0; j < POINT; j++) {
if(i + j < POINT) {
var A = Math.abs(circleArr[i + j].x - circleArr[i].x),
B = Math.abs(circleArr[i + j].y - circleArr[i].y);
var lineLength = Math.sqrt(A * A + B * B);
var C = 1 / lineLength * 7 - 0.009;
var lineOpacity = C > 0.03 ? 0.03 : C;
if(lineOpacity > 0) {
drawLine(context, circleArr[i].x, circleArr[i].y, circleArr[i + j].x, circleArr[i + j].y, lineOpacity);
}
}
}
}
}
//初始化生成原点
function init() {
circleArr = [];
for(var i = 0; i < POINT; i++) {
circleArr.push(drawCricle(context, num(WIDTH), num(HEIGHT), num(15, 2), num(10, -10) / 40, num(10, -10) / 40));
}
draw();
}
//调用执行
window.onload = function() {
init();
setInterval(function() {
for(var i = 0; i < POINT; i++) {
var cir = circleArr[i];
cir.x += cir.moveX;
cir.y += cir.moveY;
if(cir.x > WIDTH) cir.x = 0;
else if(cir.x < 0) cir.x = WIDTH;
if(cir.y > HEIGHT) cir.y = 0;
else if(cir.y < 0) cir.y = HEIGHT;
}
draw();
}, 10);
}
</script>
</body>
</html>