Returns a signed short indicating the location of p with
respect to the Reg_Cl_Plane_Curve , which must be planar.
The Reg_Cl_Plane_Curve constructors should ensure that
Reg_Cl_Plane_Curves are, but there is no guarantee that they will
not have been manipulated into a nonplanar state, by shearing, for
example.
The argument ref_pt is used within the function for
shifting a copy of the Reg_Cl_Plane_Curve to a convenient
position. It need not be the center of the Reg_Cl_Plane_Curve ,
however, classes derived from Reg_Cl_Plane_Curve will probably
have their own versions of location() , which will pass center
as the ref_pt argument to this function.
Reg_Cl_Plane_Curves need not have a meaningful center.
location() returns the following values:
 1
 p and
*this are coplanar, and p lies
outside the perimeter of *this .
 0
 p and
*this are coplanar, and p lies on the perimeter
of *this .
 1
 p and
*this are coplanar, and p lies inside
the perimeter of *this .
 2
 p and
*this are not coplanar.
 3
 Something has gone terribly wrong.
 4
 The normal to
*this has 0 magnitude, i.e., the
Points on *this are colinear.
 5
 An error occurred in putting
*this in one of
the major planes.
