为啥我的没有海葵呢？

for(var i=0;i<this.num;i++){

//beginPath,moveTo,lineTo,stroke,strokeStyle,

//lineWidth,lineCap,globalAlpha

ctx2.beginPath();

ctx2.moveTo(this.x[i],canHeight);

ctx2.lineTo(this.x[i],canHeight-this.len[i]);

ctx2.lineWidth=10;

//ctx2.lineCap="round";

ctx2.strokeStyle="purple";

ctx2.stroke();

}