[math][3d]Clockwise or counterclockwise polygon in a plane : Determining whether or not a polygon (2D) has its vertices ordered clockwise or counterclockwise : 平面上のポリゴン
[math][3d]Clockwise or counterclockwise polygon in a plane : Determining whether or not a polygon (2D) has its vertices ordered clockwise or counterclockwise : 平面上のポリゴン