function drawPolygonPath(sideNum, radius, originX, originY, ctx){  ctx.beginPath();  const unitAngle = Math.PI * 2 / sideNum; //計(jì)算單元角度  let angle = 0; //初始角度  let xLength, yLength;  // ctx.moveTo(originX, originY);  for(let i = 0; i < sideNum; i++){ //遍歷計(jì)算點(diǎn)，并lineTo()繪制路徑    xLength = radius * Math.cos(angle);    yLength = radius * Math.sin(angle);    ctx.lineTo(originX + xLength, originY - yLength);//繪制路徑    angle += unitAngle;  }  ctx.closePath();//閉合路徑，也可在for循環(huán)中多一次循環(huán)lineTo()至起點(diǎn)}