JavaScript+html5 canvas制作的百花齐放效果完整实例

本文实例讲述了JavaScript+html5 canvas制作的百花齐放效果。分享给大家供大家参考，具体如下：

运行效果截图如下：

具体代码如下：

<!DOCTYPE html>
<html>
 <head>
  <title>demo</title>
  <style type="text/css">
   body {
    margin:0; padding:0;
   }
   #canvas {
    border:5px solid gray; box-shadow:0 0 15px 15px #494949 inset;
    margin-top:50px; margin-left:200px;
   }
  </style>
 </head>
 <body >
  <canvas id="canvas" width="1000px" height="500px"></canvas>
  <script type="text/javascript">
   var dyl = {};
   dyl.canvas = document.getElementById("canvas");
   dyl.ctx = dyl.canvas.getContext("2d");
   dyl.runTime = 0;
   dyl.colorList = "01234567890ABCDEFabcdef".split("");
   dyl.colorListLength = dyl.colorList.length;
   dyl.arcList = null;
   /**
   * 得到16进制随机颜色值
   */
   dyl.getColor = function() {
    var color = "#";
    for(var i=0; i<6; i++) {
     color += dyl.colorList[Math.floor(Math.random()*dyl.colorListLength)];
    }
    return color;
   };
   /**
   * 一个随机角度，随机初始速度的斜抛对象
   */
   var Arc = function(i) {
    // 设置自有属性
    this.v = Math.round(Math.random()*100)+50;
    this.angle = Math.round(Math.random()*145) + 45;
    this.startTime = +new Date();
    this._angle = this.angle/180*Math.PI;
    this.v_x = this.v*Math.cos(this._angle);
    this.v_y_start = this.v*Math.sin(this._angle);
    this.color = dyl.getColor();
    this.x = 500;
    this.g = 250;
    this.y = 490;
    this.index = i;
    var _self = this;
    this.run = function() {
     var endTime = +new Date();
     var timeSpan = (endTime - _self.startTime)/1000;
     var v_y_now = _self.v_y_start - 1/2*_self.g*Math.pow(timeSpan, 2);
     _self.x = _self.x +_self.v_x * timeSpan;
     _self.y = _self.y - (_self.v_y_start * timeSpan - 1/2*_self.g*Math.pow(timeSpan, 2));
     return this;
    };
    return this;
   };
   /**
   * 全局绘制图像
   */
   dyl.draw = function() {
    var arcList = dyl.arcList;
    var ctx = dyl.ctx;
    dyl.runTime++;
    for(var i=0, length=arcList.length; i<length; i++) {
     var arc = arcList[i];
     if(!arc) {
      continue;
     }
     arc.run();
     ctx.save();
     ctx.beginPath();
     ctx.fillStyle = arc.color;
     ctx.arc(arc.x, arc.y, 2, 0, Math.PI*2);
     ctx.fill();
     ctx.closePath();
     ctx.restore();
    }
    console.log(dyl.runTime);
    if(dyl.runTime >= 25) {
     setTimeout(dyl.init, 1050);
    } else {
     setTimeout(dyl.draw, 20);
    }
   };
   /**
   * 初始化整个事件
   */
   dyl.init = function() {
    dyl.ctx.clearRect(0, 0, 1000, 500);
    dyl.arcList = [];
    dyl.runTime = 0;
    for(var i=0; i<100; i++) {
     dyl.arcList.push(new Arc(i));
    }
    dyl.draw();
   };
   dyl.init();
  </script>
 </body>
</html>

更多关于js特效相关内容感兴趣的读者可查看本站专题：《jQuery动画与特效用法总结》及《jQuery常见经典特效汇总》

希望本文所述对大家JavaScript程序设计有所帮助。