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在WEB里绘制爱心

php中世界最好的语言asal: 2017-12-30 17:58:183366semak imbas

这次给大家带来的是怎样在WEB里绘制爱心，话不多说，下面直接献上案例，给大家好好分析一下。

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>使用桃心形方程绘制爱心</title>
</head>
<body>
 <canvas></canvas>
 <script>
 var canvas = document.querySelector(&#39;canvas&#39;);
 var ctx = canvas.getContext(&#39;2d&#39;);
 canvas.width = window.innerWidth;
 canvas.height = window.innerHeight;
 var Heart = function(x, y) {
  this.x = x;
  this.y = y;
  this.vertices = [];
  for(let i=0; i<30; i++) {
  var step = i / 30 * (Math.PI * 2);//设置心上面两点之间的角度
  var vector = {
   x : (15 * Math.pow(Math.sin(step), 3)),
   y : -(13 * Math.cos(step) - 5 * Math.cos(2 * step) - 2 * Math.cos(3 * step) - Math.cos(4 * step))
  }
  this.vertices.push(vector);
  }
 }
 Heart.prototype.draw = function() {
  ctx.translate(-1000,this.y);//这一步跟ctx.shadowOffsetX必须一起使用
  ctx.beginPath();
  for(let i=0; i<30; i++) {
  var vector = this.vertices[i];
  ctx.lineTo(vector.x, vector.y);
  }
  ctx.shadowColor = "red";
  ctx.shadowOffsetX = this.x+1000;
  ctx.fill();
 }
 canvas.onmousedown = function(e) {
  var x = e.offsetX;
  var y = e.offsetY;
  var heart = new Heart(x, y);
  heart.draw();
 }
 </script>
</body>
</html>

相信看了以上介绍你已经掌握了方法，更多精彩请关注php中文网其它相关文章！

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