［WEB］知乎登录背景——html/css/js实现

来源：互联网发布：php计算数组重复编辑：程序博客网时间：2024/05/19 02:18
一.源代码
<!DOCTYPE html><html>  <head>    <meta charset="utf-8">    <title>IFE JavaScript Task 01</title>  </head>  <style>    html,body{      width:100%;      height:100%;      overflow:hidden;    }  </style><body><canvas id="Mycanvas"></canvas><script type="text/javascript">//定义画布宽高和生成点的个数  var WIDTH = window.innerWidth;  var HEIGHT = window.innerHeight;  var POINT = 35;  var canvas = document.getElementById('Mycanvas');  canvas.width = WIDTH;  canvas.height = HEIGHT;  var context = canvas.getContext('2d');  context.strokeStyle = 'rgba(0,0,0,0.04)',  context.strokeWidth = 1,  context.fillStyle = 'rgba(0,0,0,0.08)';  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();  }  //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();  }  //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);          }        }      }    }  }  //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();    }, 16);  }</script></body></html>
二.实现
参考网址：http://en.jsrun.net/UUpKp/edit
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