不规则多边形面积计算

    public static double getArea(int iCount, double[] x, double[] y)
    {
        double s=0;
        if (icount < 3)
            return 0;
        s = y[0] * (x[icount - 1] - x[1]); //S初始值
        for (int i = 1; i < icount; i++)
        {
            s += y[i] * (x[(i-1)] - x[(i + 1) % icount]);   //累加S面积
        }
        return   Math.Abs(s / 2);
    }

 

iCount为点个数，double[]x 为x轴的点数组double[] y 为y轴点数组