Canvas 绘制粒子动画背景

时间：2021-05-28

效果如下：

代码如下：

<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Title</title></head><style> *{ margin:0px; padding:0px; } body{ background:#000; } canvas{ position:absolute; width:100%; height:100%; }</style><body><canvas id="canvas">您的浏览器不支持，请升级最新的版本!</canvas><script>window.requestAnimFrame = ( function() { return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function( callback ) { window.setTimeout( callback, 1000 / 60 ); };})();var can = document.getElementById("canvas");var cxt = can.getContext("2d");can.width = window.innerWidth;can.height = window.innerHeight;cxt.lineWidth = 0.3;//初始链接线条显示位置var mousePosition = { x : 30*can.width/100, y : 30*can.height/100}//圆形粒子对象参数var dots = { n : 500,//圆形粒子个数 distance : 50,//圆形粒子之间的距离 d_radius : 80,//粒子距离鼠标点的距离 array : []//保存n个圆形粒子对象}//创建随机颜色值function colorValue(min){ return Math.floor(Math.random()*255 + min);}function createColorStyle(r,g,b){ return "rgba("+r+","+g+","+b+", 1)";}//混合两个圆形粒子的颜色function mixConnect(c1,r1,c2,r2){//圆的颜色 半径 return (c1*r1+c2*r2)/(r1+r2);};//生成线条的颜色function lineColor(dot1,dot2){//获取具体的圆的颜色再计算 var color1 = dot1.color, color2 = dot2.color; var r = mixConnect(color1.r,dot1.radius,color2.r,dot2.radius); var g = mixConnect(color1.g,dot1.radius,color2.g,dot2.radius); var b = mixConnect(color1.b,dot1.radius,color2.b,dot2.radius); return createColorStyle(Math.floor(r),Math.floor(g),Math.floor(b));}//生成圆形粒子的颜色对象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);}//创建圆形粒子对象function Dot(){ //圆形粒子随机圆心坐标点 this.x = Math.random()*can.width; this.y = Math.random()*can.height; //x y 方向运动的速度值 this.vx = -0.5 + Math.random(); this.vy = -0.5 + Math.random(); this.radius = Math.random()*5; //this.color = "#ff3333"; this.color = new Color();}//绘制出圆形粒子Dot.prototype.draw = function(){ cxt.beginPath(); cxt.fillStyle = this.color.style; cxt.arc(this.x,this.y,this.radius,0,Math.PI*2,false); cxt.fill();}//添加圆形粒子function createCircle(){ for (var i=0;i<dots.n ;i++ ) { dots.array.push(new Dot()); }}//绘制出圆形粒子function drawDots(){ for (var i=0;i<dots.n ;i++ ) { var dot = dots.array[i]; dot.draw(); }}//drawDots();//移动function moveDots(){ for (var i=0;i<dots.n ;i++ ){ var dot = dots.array[i]; //当圆形粒子对象碰壁的时候就反弹回来 if (dot.y < 0 || dot.y > can.height) { dot.vx = dot.vx; dot.vy = -dot.vy; }else if (dot.x < 0 || dot.x > can.width) { dot.vx = -dot.vx; dot.vy = dot.vy; } //给圆形粒子圆心坐标加上速度值移动圆形粒子 dot.x += dot.vx; dot.y += dot.vy; }}//链接粒子对象function connectDots(){ for (var i=0;i<dots.n ; i++) { for ( var j=0;j<dots.n ; j++) { iDot = dots.array[i]; jDot = dots.array[j]; if ((iDot.x - jDot.x) < dots.distance && (iDot.y - jDot.y) < dots.distance && (iDot.x - jDot.x) > -dots.distance && (iDot.y - jDot.y) > -dots.distance) { if ((iDot.x - mousePosition.x) < dots.d_radius && (iDot.y - mousePosition.y) < dots.d_radius && (iDot.x - mousePosition.x) > -dots.d_radius && (iDot.y - mousePosition.y) > -dots.d_radius) { cxt.beginPath(); //cxt.strokeStyle = "yellow"; cxt.strokeStyle = lineColor(iDot,jDot); cxt.moveTo(iDot.x,iDot.y); cxt.lineTo(jDot.x,jDot.y); cxt.closePath(); cxt.stroke(); } } } }}createCircle();//让圆形粒子不断的移动function animateDots(){ cxt.clearRect(0,0,can.width,can.height); moveDots(); connectDots() drawDots(); requestAnimFrame(animateDots);}animateDots();can.onmousemove = function(ev){ var ev = ev || window.event; mousePosition.x = ev.pageX; mousePosition.y = ev.pageY;}can.onmouseout = function(){ mousePosition.x = can.width/2; mousePosition.y = can.height/2;}</script></body></html>

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