jQuery+canvas实现简单的球体斜抛及颜色动态变换效果

jQuery+canvas实现简单的球体斜抛及颜色动态变换效果_jquery

WBOY

发布： 2016-05-16 15:17:18

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本文实例讲述了jQuery+canvas实现简单的球体斜抛及颜色动态变换效果。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 PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>canvas简单斜抛</title>
  <script src="jquery-1.7.1.min.js" type="text/javascript"></script>
  <script type="text/javascript" >
    var canvasHeight = 0;
    var canvasWidth = 0;
    var g = 9.8;
    function Cast(context, castSettings) {
      Cast.createColor = function () {
        var r = Math.round(Math.random() * 256),
          g = Math.round(Math.random() * 256),
          b = Math.round(Math.random() * 256);
        return "rgb("+r+","+g+","+b+")";
      }
      var _self = this;
      // x, y, radian, r, v
      $.extend(_self, castSettings);
      _self.radian = _self.radian / 180 * Math.PI;
      _self.vo = _self.v;
      _self.vxo = Math.cos(_self.radian) * _self.vo;
      _self.vyo = Math.sin(_self.radian) * _self.vo;
      console.log("vyo:"+_self.vyo+":vxo:"+_self.vxo+":"+_self.radian);
      _self.prevTime = new Date().getTime();
      _self.xo = _self.x;
      _self.yo = _self.y;
      _self.cast = function () {
        if (_self.x > canvasWidth - _self.r || _self.y > _self.yo) {
          return;
        }
        var time = (new Date().getTime() - _self.prevTime) / 1000;
        var x = _self.vxo * time;
        var y = _self.vyo * time - 1 / 2 * g * time * time;
        console.log(time+":"+_self.yo+":"+_self.xo+":"+y);
        context.beginPath();
        context.fillStyle = Cast.createColor();
        context.arc(x + _self.xo, _self.yo- y , _self.r, 0, 2 * Math.PI);
        context.fill();
        context.closePath();
        _self.x = x + _self.xo;
        _self.y = _self.yo - y;
        setTimeout(function () {
          _self.cast();
        }, 30);
      }
      _self.cast();
    }
    $(document).ready(function () {
      var canvas = $("#canvas");
      var context = canvas.get(0).getContext('2d');
      canvasHeight = canvas.height();
      canvasWidth = canvas.width();
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 20 });
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 30 });
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 40 });
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 50 });
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 60 });
      new Cast(context, { x: 0, y: 400, v: 70, r: 5, radian: 70 });
    });
  </script>
  <style type="text/css" >
    h2 { color:Gray; line-height:50px; }
    #canvas { background:#DDDDDD;}
  </style>
</head>
<body>
 <center>
 <h3>canvas实现斜抛效果</h3>
 <hr />
 <canvas id="canvas" width="500" height="500"></canvas>
 <hr />
 </center>
</body>
</html>

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