Determine whether point P is above or below a vector through points A, B
Possible values for 
:
0 On the vector
> 0 Above the vector
< 0 Below the vector
The function above is the ‘2D cross product’, therefore z is the surface of vector 
and 
. Dividing the surface by the length of vector (
) gives the ‘signed distance’ of the point perpendicular to the point 
.