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// $Id: G4VIntersectionLocator.hh,v 1.6 2009/11/30 11:39:15 japost Exp $
// GEANT4 tag $Name: geant4-09-04-ref-00 $
//
//
// Class G4VIntersectionLocator 
//
// class description:
// 
// Base class for the calculation of the intersection point with a boundary 
// when PropagationInField is used.
// Gives possibility to choose the method of intersection; concrete locators
// implemented are: G4SimpleLocator, G4MultiLevelLocator, G4BrentLocator.
//
// Key Method: EstimateIntersectionPoint()

// History:
// -------
// 27.10.08 - John Apostolakis, Tatiana Nikitina: Design and implementation 
// ---------------------------------------------------------------------------

#ifndef G4VINTERSECTIONLOCATOR_HH
#define G4VINTERSECTIONLOCATOR_HH

#include "G4Types.hh" 
#include "G4ThreeVector.hh"
#include "G4FieldTrack.hh"

#include "G4Navigator.hh"
#include "G4ChordFinder.hh"

class G4VIntersectionLocator
 {
   public:  // with description 
 
     G4VIntersectionLocator(G4Navigator *theNavigator);
       // Constructor
     virtual ~G4VIntersectionLocator();
       // Default destructor
     
     virtual G4bool EstimateIntersectionPoint( 
         const  G4FieldTrack&       curveStartPointTangent,  // A
         const  G4FieldTrack&       curveEndPointTangent,    // B
         const  G4ThreeVector&      trialPoint,              // E
                G4FieldTrack&       intersectPointTangent,   // Output
                G4bool&             recalculatedEndPoint,    // Out
                G4double&           fPreviousSafety,         // In/Out
                G4ThreeVector&      fPreviousSftOrigin) = 0; // In/Out   
       // If such an intersection exists, this function calculates the
       // intersection point of the true path of the particle with the surface
       // of the current volume (or of one of its daughters). 
       // Should use lateral displacement as measure of convergence
       // NOTE: changes the safety!

     void printStatus( const G4FieldTrack& startFT,
                       const G4FieldTrack& currentFT, 
                             G4double      requestStep, 
                             G4double      safety,
                             G4int         step);
       // Print Method, useful mostly for debugging

     inline G4bool IntersectChord( G4ThreeVector  StartPointA, 
                                   G4ThreeVector  EndPointB,
                                   G4double      &NewSafety,
                                   G4double      &fPreviousSafety,    // In/Out
                                   G4ThreeVector &fPreviousSftOrigin, // In/Out
                                   G4double      &LinearStepLength,
                                   G4ThreeVector &IntersectionPoint);
       // Intersect the chord from StartPointA to EndPointB and return
       // whether an intersection occurred. NOTE: changes the Safety!

     inline void    SetEpsilonStepFor( G4double EpsilonStep );
     inline void    SetDeltaIntersectionFor( G4double deltaIntersection );
     inline void    SetNavigatorFor( G4Navigator *fNavigator );
     inline void    SetChordFinderFor(G4ChordFinder *fCFinder );
       // These parameters must be set at each step, in case they were changed

       // Note: This simple approach ensures that all scenarios are considered. 
       //   [ Future refinement may identify which are invariant during a 
       //      track, run or event ]

    inline void     SetVerboseFor(G4int fVerbose);
    inline G4int    GetVerboseFor();
       // Controling verbosity enables checking of the locating of intersections

  public:  // without description
    // Additional inline Set/Get methods for parameters, dependent objects

    inline G4double       GetDeltaIntersectionFor();
    inline G4double       GetEpsilonStepFor();
    inline G4Navigator*   GetNavigatorFor();
    inline G4ChordFinder* GetChordFinderFor();

    inline void   SetSafetyParametersFor(G4bool UseSafety );

    inline void   AddAdjustementOfFoundIntersection(G4bool UseCorrection);
    inline G4bool GetAdjustementOfFoundIntersection();
      // Methods to be made Obsolete - replaced by methods below
    inline void   AdjustIntersections(G4bool UseCorrection); 
    inline G4bool AreIntersectionsAdjusted(){ return fUseNormalCorrection; }  
      // Change adjustment flag  ( New Interface ) 

  protected:  // with description

    G4FieldTrack ReEstimateEndpoint( const G4FieldTrack &CurrentStateA,  
                                     const G4FieldTrack &EstimtdEndStateB,
                                           G4double      linearDistSq,
                                           G4double      curveDist);
      // Return new estimate for state after curveDist starting from
      // CurrentStateA, to replace EstimtdEndStateB, and report displacement
      // (if field is compiled verbose)

     
    G4ThreeVector GetLocalSurfaceNormal(const G4ThreeVector &CurrentE_Point,
                                              G4bool &validNormal);
      // Return the SurfaceNormal of Intersecting Solid

    G4bool AdjustmentOfFoundIntersection(const G4ThreeVector &A,
                                         const G4ThreeVector &CurrentE_Point, 
                                         const G4ThreeVector &CurrentF_Point,
                                         const G4ThreeVector &MomentumDir,
                                         const G4bool         IntersectAF, 
                                               G4ThreeVector &IntersectionPoint,
                                               G4double      &NewSafety,
                                               G4double      &fPrevSafety,
                                               G4ThreeVector &fPrevSftOrigin );
      // Optional method for adjustment of located intersection point
      // using the surface-normal
  
  protected:

    G4double kCarTolerance;         // Constant

    G4int    fVerboseLevel;          // For debugging
    G4bool   fUseNormalCorrection;   // Configuration parameter

    G4Navigator   *fiNavigator;
      // Parameters set by G4PropagatorInField  ( when ? ) 

    G4ChordFinder *fiChordFinder;
    G4double       fiEpsilonStep;
    G4double       fiDeltaIntersection;
    G4bool         fiUseSafety;
      // Parameters set at each physical step by calling method - G4PropagatorInField

    G4Navigator *fHelpingNavigator;
      // Helper for location
};

#include "G4VIntersectionLocator.icc"

#endif
