Canvas多边形绘制的实现方法

function drawPolygonPath(sideNum, radius, originX, originY, ctx){  ctx.beginPath();  const unitAngle = Math.PI * 2 / sideNum; //计算单元角度  let angle = 0; //初始角度  let xLength, yLength;  // ctx.moveTo(originX, originY);  for(let i = 0; i < sideNum; i++){ //遍历计算点，并lineTo()绘制路径    xLength = radius * Math.cos(angle);    yLength = radius * Math.sin(angle);    ctx.lineTo(originX + xLength, originY - yLength);//绘制路径    angle += unitAngle;  }  ctx.closePath();//闭合路径，也可在for循环中多一次循环lineTo()至起点}