case 4:   // Third order polynomial

            // Check whether the 4 centers co-planar
            PlaneNormal = cross(Segment->Center_Coef[1]-Segment->Center_Coef[0],
                                Segment->Center_Coef[2]-Segment->Center_Coef[0]);

            if (fabs(dot(PlaneNormal,Segment->Center_Coef[3]-Segment->Center_Coef[0])) < EPSILON)
            {
                PointsCoplanar = true;
                PlaneNormal.normalize();
                if (fabs(dot(PlaneNormal,ray.Direction)) > 1.0-EPSILON)
                    RayPerpToCoplanarPoints = true;
            }

            if (RayPerpToCoplanarPoints)
            {
                // If have coplanar points and ray direction perpendicular to that plane, special handling.
                //
                // Massimo Valentini, described the issue this way:
                //
                //   The problem is that the intersection between a planar speresweep and a ray
                //   orthogonal to the plane is ill-conditioned. The equation is a polynomial
                //   that is a perfect square:
                //
                //       p(d) = p2(d) * p2(d)
                //
                //   meaning that it is always non negative and zero only on the surface.
                //

                // Get the intersection with plane
                NormalDotDirection = dot(PlaneNormal,ray.Direction);
                if (NormalDotDirection >= EPSILON)
                {
                    t = fabs(dot(Segment->Center_Coef[0] - ray.Origin, PlaneNormal) / NormalDotDirection);
                    // Hack in the intersection pending some magic not invented...
                    if((t > -MAX_DISTANCE) && (t < MAX_DISTANCE))
                    {
                        IPoint = ray.Evaluate(t);
                        if (this->Inside(IPoint, Thread))
                        {
                            // Add intersection
                            Isect[Isect_Count].t = t;

                            // Calculate point
                            Isect[Isect_Count].Point = IPoint;

                            // Set normal
                            Isect[Isect_Count].Normal = PlaneNormal;

                            Isect_Count++;
                        }

                    }
                }
                Num_Poly_Roots = 0;

            }
            else