任意多边形A1，A2，A3….An;的面积计算公式如下

area=0.5*abs(x1*y2-x2*y1+x2*y3-x3*y2+x3*y4-x4*y3…….x(n-1)*yn-xn*y(n-1)+xn*y1-x1*yn);

重心座标公式如下：

x=(x1+x2)*(x1*y2-x2*y1)+(x2+x3)*(x2*y3-x3*y2)+…….+(xn+x1)*(xn*y1-x1*yn);

x=x/(6*area);

y=(y1+y2)*(x1*y2-x2*y1)+(y2+y3)*(x2*y3-x3*y2)+…….+(yn+y1)*(xn*y1-x1*yn);

y=y/(6*area);