Reconstruction/MdcPatRec/TrkBase/include/TrkBase/TrkPocaBase.h

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//--------------------------------------------------------------------------
// File and Version Information:
//      $Id: TrkPocaBase.h,v 1.2 2006/03/28 01:02:36 zhangy Exp $
//
// Description:
//   Base class for various Poca classes; holds infrastructure, and one
//   common algorithm.  Ctor and dtor protected, to prevent instantiation.
//
// Environment:
//      Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author(s): Steve Schaffner
//------------------------------------------------------------------------
#ifndef TRKPOCABASE_H
#define TRKPOCABASE_H
 
#include "CLHEP/Geometry/Point3D.h"
#include "TrkBase/TrkErrCode.h"
#ifndef ENABLE_BACKWARDS_COMPATIBILITY
typedef HepGeom::Point3D<double> HepPoint3D;
#endif
class Trajectory;
 
// Class interface
class TrkPocaBase {
 
protected:
  TrkPocaBase( double flt1, double flt2, double precision );
  TrkPocaBase( double flt1, double precision );
  virtual ~TrkPocaBase();
 
public:
  inline const TrkErrCode& status() const; // did the calculation succeed?
  inline double            flt1() const;   // path length on traj 1 @ poca
  inline double            flt2() const;
  inline double            precision(); // In case anyone wants to know
 
protected:
  double     _precision;
  double     _flt1;
  double     _flt2;
  TrkErrCode _status;
 
  void minimize( const Trajectory& traj1, double f1, const Trajectory& traj2, double f2 );
  void minimize( const Trajectory& traj1, double f1, const HepPoint3D& pt );
 
  void stepTowardPoca( const Trajectory& traj1, const Trajectory& traj2 );
  void stepToPointPoca( const Trajectory& traj, const HepPoint3D& pt );
 
  static double _maxDist; // step > maxDist => parallel
  static int    _maxTry;
  static double _extrapToler; // error allowed in picking step size
};
 
// Inlined functions
double TrkPocaBase::precision() { return _precision; }
 
const TrkErrCode& TrkPocaBase::status() const { return _status; }
 
double TrkPocaBase::flt1() const { return _flt1; }
 
double TrkPocaBase::flt2() const { return _flt2; }
 
#endif