需具备js基础知识以及canvas相关方法(可查阅相关文档)
下面是一篇有关js与canvas的背景特效
基于面向过程的思维
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style>
*{
margin: 0;
padding: 0;
}
#canvas {
display: block;
background: #000;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
window.requestAnimationFrame =(function(){//解决定时器卡问题，使用帧动画
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
function(callback){
window.setInterval (callback,1000/60);
};
})();
//初始化变量
var canv=document.getElementsByName("canvas");
var cxt=canvas.getContext("2d");
var w,h;
var num=200;
var data=[];
var move={};
window.onresize=init;//在浏览器窗口变化时重置
init();
//获取浏览器宽高并使粒子随机分布
function init(){
canvas.width = window.innerWidth ;
canvas.height = window.innerHeight ;
w = canvas.width;
h = canvas.height;
for(var i=0;i<num;i++){
data[i]={x:Math.random()*w,y:Math.random()*h,cX:Math.random()*0.6-0.3,cY:Math.random()*0.6-0.3};
Cricle(data[i].x,data[i].y);
}
}
//绘制粒子
function Cricle(x,y){
cxt.save();
cxt.fillStyle ="pink";
cxt.beginPath ();
cxt.arc (x,y,0.5,Math.PI*2,false);
cxt.closePath ();
cxt.fill ();
cxt.restore ();
}
//自执行使粒子运动
!function draw(){
cxt.clearRect(0,0,w,h);//清除，防止粒子运动成线
for(var i=0;i<num;i++){
data[i].x+=data[i].cX;//粒子运动
data[i].y+=data[i].cY;
if(data[i].x>w||data[i].x<0) data[i].cX=-data[i].cX;//设置边界值判断防止粒子跑出边界
if(data[i].y>h||data[i].y<0) data[i].cY=-data[i].cY;
Cricle(data[i].x,data[i].y);
for(var j=i+1;j<num;j++){
//使粒子连线
if((data[i].x-data[j].x)*(data[i].x-data[j].x)+(data[i].y-data[j].y)*(data[i].y-data[j].y)<=50*50){
line(data[i].x,data[i].y,data[j].x,data[j].y,false);
}
//使粒子与鼠标连线
if(move.x){
if((data[i].x-move.x)*(data[i].x-move.x)+(data[i].y-move.y)*(data[i].y-move.y)<=100*100){
line(data[i].x,data[i].y,move.x,move.y,true);
}
}
}
}
window.requestAnimationFrame(draw);//定时器
// setInterval(function(){
// draw();
// },130);
}();
//使粒子的连线颜色渐变
function line(x1,y1,x2,y2,isMove){
var color=cxt.createLinearGradient(x1,y1,x2,y2);
if(!isMove){
color.addColorStop(0,"yellow");
color.addColorStop(1,"pink");
}else{
color.addColorStop(0,"#fff");
color.addColorStop(1,"#0bd2dd");
}
cxt.save();
cxt.strokeStyle=color;
cxt.beginPath();
cxt.moveTo(x1,y1);
cxt.lineTo(x2,y2);
cxt.stroke();
cxt.restore();
}
//鼠标移入与粒子连线
document.onmousemove=function(e){
move.x= e.clientX;
move.y= e.clientY;
}
</script>
</body>
</html>
