G4CachedMagneticField.hh

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//
// G4CachedMagneticField
//
// Class description:
//
// Caches Magnetic Field value, for field whose evaluation is expensive.

// Author: J.Apostolakis, 20 July 2009.
// --------------------------------------------------------------------
#ifndef G4CACHED_MAGNETIC_FIELD_HH
#define G4CACHED_MAGNETIC_FIELD_HH

#include "G4Types.hh"
#include "G4ThreeVector.hh"
#include "G4MagneticField.hh"

class G4CachedMagneticField : public G4MagneticField
{
  public:  // with description

     G4CachedMagneticField(G4MagneticField*, G4double distanceConst);
     virtual ~G4CachedMagneticField();
       // Constructor and destructor. No actions.

     G4CachedMagneticField(const G4CachedMagneticField& r);
     G4CachedMagneticField& operator = (const G4CachedMagneticField& p);
       // Copy constructor & assignment operator.

     virtual void  GetFieldValue( const G4double Point[4],
                                        G4double* Bfield ) const;
     
     G4double GetConstDistance() const         { return fDistanceConst; } 
     void     SetConstDistance( G4double dist ){ fDistanceConst= dist;}

     G4int GetCountCalls() const { return fCountCalls; }
     G4int GetCountEvaluations() const { return fCountEvaluations; } 
     void  ClearCounts() { fCountCalls = 0; fCountEvaluations=0; }
     void  ReportStatistics();
    
    virtual G4Field* Clone() const;

  protected:

     mutable G4int fCountCalls = 0, fCountEvaluations = 0;  

  private:

     G4MagneticField* fpMagneticField = nullptr;
     G4double fDistanceConst;
       // When the field is evaluated within this distance it will not change

     // Caching state
     //
     mutable G4ThreeVector fLastLocation;
     mutable G4ThreeVector fLastValue;
};

#endif /* G4CACHED_MAGNETIC_FIELD_DEF */