text: /**
   * Created by rowthan on 2017/5/16.
   */
  /**
   * Created by https://github.com/sunshine940326
   */
  class Circle {
      //创建对象
      //以一个圆为对象
      //设置随机的 x，y坐标，r半径，_mx，_my移动的距离
      //this.r是创建圆的半径，参数越大半径越大
      //this._mx,this._my是移动的距离，参数越大移动
      constructor(x, y) {
          this.x = x;
          this.y = y;
          this.r = Math.random() * 10 ;
          this._mx = Math.random() ;
          this._my = Math.random() ;
  
      }
  
      //canvas 画圆和画直线
      //画圆就是正常的用canvas画一个圆
      //画直线是两个圆连线，为了避免直线过多，给圆圈距离设置了一个值，距离很远的圆圈，就不做连线处理
      drawCircle(ctx) {
          ctx.beginPath();
          //arc() 方法使用一个中心点和半径，为一个画布的当前子路径添加一条弧。
          ctx.arc(this.x, this.y, this.r, 0, 360)
          ctx.closePath();
          ctx.fillStyle = 'rgba(204, 204, 204, 0.3)';
          ctx.fill();
      }
  
      drawLine(ctx, _circle) {
          let dx = this.x - _circle.x;
          let dy = this.y - _circle.y;
          let d = Math.sqrt(dx * dx + dy * dy)
          if (d < 150) {
              ctx.beginPath();
              //开始一条路径，移动到位置 this.x,this.y。创建到达位置 _circle.x,_circle.y 的一条线：
              ctx.moveTo(this.x, this.y);   //起始点
              ctx.lineTo(_circle.x, _circle.y);   //终点
              ctx.closePath();
              ctx.strokeStyle = 'rgba(204, 204, 204, 0.3)';
              ctx.stroke();
          }
      }
  
      // 圆圈移动
      // 圆圈移动的距离必须在屏幕范围内
      move(w, h) {
          this._mx = (this.x < w && this.x > 0) ? this._mx : (-this._mx);
          this._my = (this.y < h && this.y > 0) ? this._my : (-this._my);
          this.x += this._mx / 2;
          this.y += this._my / 2;
      }
  }
  //鼠标点画圆闪烁变动
  class currentCirle extends Circle {
      constructor(x, y) {
          super(x, y)
      }
  
      drawCircle(ctx) {
          ctx.beginPath();
          //注释内容为鼠标焦点的地方圆圈半径变化
          //this.r = (this.r < 14 && this.r > 1) ? this.r + (Math.random() * 2 - 1) : 2;
          this.r = 8;
          ctx.arc(this.x, this.y, this.r, 0, 360);
          ctx.closePath();
          //ctx.fillStyle = 'rgba(0,0,0,' + (parseInt(Math.random() * 100) / 100) + ')'
          ctx.fillStyle = 'rgba(255, 77, 54, 0.6)'
          ctx.fill();
  
      }
  }
  //更新页面用requestAnimationFrame替代setTimeout
  window.requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
  
  let canvas = document.getElementById('canvas');
  let ctx = canvas.getContext('2d');
  let w = canvas.width = canvas.offsetWidth;
  let h = canvas.height = canvas.offsetHeight;
  let circles = [];
  let current_circle = new currentCirle(0, 0)
  
  let draw = function () {
      ctx.clearRect(0, 0, w, h);
      for (let i = 0; i < circles.length; i++) {
          circles[i].move(w, h);
          circles[i].drawCircle(ctx);
          for (j = i + 1; j < circles.length; j++) {
              circles[i].drawLine(ctx, circles[j])
          }
      }
      if (current_circle.x) {
          current_circle.drawCircle(ctx);
          for (var k = 1; k < circles.length; k++) {
              current_circle.drawLine(ctx, circles[k])
          }
      }
      requestAnimationFrame(draw)
  }
  
  let init = function (num) {
      for (var i = 0; i < num; i++) {
          circles.push(new Circle(Math.random() * w, Math.random() * h));
      }
      draw();
  }
  window.addEventListener('load', init(60));
  window.onmousemove = function (e) {
      e = e || window.event;
      current_circle.x = e.clientX;
      current_circle.y = e.clientY;
  }
  window.onmouseout = function () {
      current_circle.x = null;
      current_circle.y = null;
  
  };