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// $Id: G4SafetyHelper.hh,v 1.7 2007/05/02 15:32:13 japost Exp $
// GEANT4 tag $Name: geant4-09-02-cand-01 $
//
//
// class G4SafetyHelper
//
// Class description:
//
// This class is a helper for physics processes which require 
// knowledge of the safety, and the step size for the 'mass' geometry

// First version:  J. Apostolakis,  July 5th, 2006
// Modified:
//  10.04.07 V.Ivanchenko  Use unique G4SafetyHelper
// --------------------------------------------------------------------

#ifndef G4SAFETYHELPER_HH
#define G4SAFETYHELPER_HH 1

#include <vector>

#include "G4Types.hh"
#include "G4ThreeVector.hh"
#include "G4Navigator.hh"

class G4PathFinder;

class G4SafetyHelper
{
public: // with description

  G4SafetyHelper(); 
  ~G4SafetyHelper();
     //
     // Constructor and destructor

  G4double CheckNextStep( const G4ThreeVector& position, 
                          const G4ThreeVector& direction,
                          const G4double currentMaxStep,
                                G4double& newSafety );
     //
     // Return linear step for mass geometry

  G4double ComputeSafety( const G4ThreeVector& pGlobalPoint ); 
     //
     // Return safety for all geometries

  void Locate(const G4ThreeVector& pGlobalPoint,
              const G4ThreeVector& direction);
     //
     // Locate the point for all geometries

  void ReLocateWithinVolume(const G4ThreeVector& pGlobalPoint );
     //
     // Relocate the point in the volume of interest

  inline void EnableParallelNavigation(G4bool parallel);
     // 
     //  To have parallel worlds considered, must be true.
     //  Alternative is to use single (mass) Navigator directly

  void InitialiseNavigator();
     //
     // Check for new navigator for tracking, and reinitialise pointer

  inline G4VPhysicalVolume* GetWorldVolume();
  inline void SetCurrentSafety(G4double val, const G4ThreeVector& pos);

public: // without description

  void InitialiseHelper();

private:

  G4PathFinder* fpPathFinder;
  G4Navigator*  fpMassNavigator;
  G4int         fMassNavigatorId;

  G4bool        fUseParallelGeometries; 
    // Flag whether to use PathFinder or single (mass) Navigator directly
  G4bool fFirstCall;
    // Flag of first call

  // State used during tracking -- for optimisation
  G4ThreeVector fLastSafetyPosition;
  G4double      fLastSafety;
  const G4double  fRecomputeFactor;   
       // parameter for further optimisation: 
       // if ( move < fact*safety )  do fast recomputation of safety
  // End State (tracking)
};

// Inline definitions

inline
void G4SafetyHelper::EnableParallelNavigation(G4bool parallel) 
{
  fUseParallelGeometries = parallel;
} 

inline
G4VPhysicalVolume* G4SafetyHelper::GetWorldVolume()
{
  return fpMassNavigator->GetWorldVolume();
}

inline
void G4SafetyHelper::SetCurrentSafety(G4double val, const G4ThreeVector& pos)
{
  fLastSafety = val;
  fLastSafetyPosition = pos;
}

#endif
