///////////////////////////////////////////////////////////////////////
//
// Given two points, ra and rb, this subroutine returns the points, rcross1
// and rcross2, at which the line co-inciding with the vector from ra to rb
// intersects the sphere with radius SphRad.

// The routine returns false if there is no intersection.
// If one point is in the same and one is in the opposite direction of the
// vector from ra to rb, it returns as rcross1 the point in the same
// direction.
// If both intersection points in the same direction from ra, rcross1 is set
// to the point closer to ra.
// f1 and f2 are the multiples of the distance between ra and rb at which
// the intersecion points are located.

//
// Author: W. Heintzelman <billh@hep.upenn.edu>
//
// REVISION HISTORY:
//     02/12/2014 : W. Heintzelman - New file
//     10/24/2018 : W. Heintzelman - Extensive revisions
//
////////////////////////////////////////////////////////////////////////
#ifndef __RAT_SphereCrossPoint__
#define __RAT_SphereCrossPoint__
#include <TVector3.h>

namespace RAT
{

bool SphereCrossPoint(double SphRad,TVector3& ra,TVector3& rb,
         TVector3& rcross1, TVector3& rcross2, double& f1, double& f2 );

}   // namespace RAT
#endif