Given a polygon with N vertices without any order, The area is given by $A=\frac{\mathrm{1}}{\mathrm{2}}\sum _{i=0}^{N-1}({x}_{i}{y}_{i+1}-{x}_{i+1}{y}_{i}),$if the sign of the above expression is positive then the polygon vertices are ordered counter clockwise about the normal, otherwise clockwise.