G4PathFinder.hh

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//
// class G4PathFinder 
//
// Class description:
// 
// This class directs the lock-stepped propagation of a track in the 
// 'mass' and other parallel geometries.  It ensures that tracking 
// in a magnetic field sees these parallel geometries at each trial step, 
// and that the earliest boundary limits the step.
// 
// For the movement in field, it relies on the class G4PropagatorInField

// History:
// -------
//  7.10.05 John Apostolakis,  Draft design 
// 26.04.06 John Apostolakis,  Revised design and first implementation 
// ---------------------------------------------------------------------------
#ifndef G4PATHFINDER_HH 
#define G4PATHFINDER_HH  1

#include <vector>
#include "G4Types.hh"

#include "G4FieldTrack.hh"

class G4TransportationManager; 
class G4Navigator;

#include "G4TouchableHandle.hh"
#include "G4FieldTrack.hh"
#include "G4MultiNavigator.hh"

class G4PropagatorInField;

class G4PathFinder
{

 public:  // with description

   static G4PathFinder* GetInstance();
     // Retrieve singleton instance and create it if not existing.

   static G4PathFinder* GetInstanceIfExist();
     // Retrieve singleton instance pointer.

   G4double ComputeStep( const G4FieldTrack& pFieldTrack,
                         G4double  pCurrentProposedStepLength,
                         G4int     navigatorId, // Identifies the geometry
                         G4int     stepNo,      // See next step/check 
                         G4double& pNewSafety,  // Only for this geometry
                         ELimited& limitedStep,      
                         G4FieldTrack& EndState, 
                         G4VPhysicalVolume* currentVolume );
     // Compute the next geometric Step -- curved or linear
     // If it is called with a larger 'stepNo' it will execute a new step;
     // if 'stepNo' is same as last call, then the results for 
     // the geometry with Id. number 'navigatorId' will be returned. 

   void Locate( const G4ThreeVector& position, 
                const G4ThreeVector& direction,
                      G4bool relativeSearch = true); 
     // Make primary relocation of global point in all navigators,
     // and update them.

   void ReLocate( const G4ThreeVector& position ); 
     // Make secondary relocation of global point (within safety only) 
     // in all navigators, and update them.

   void PrepareNewTrack( const G4ThreeVector& position,
                         const G4ThreeVector& direction,
                               G4VPhysicalVolume* massStartVol = nullptr); 
     // Check and cache set of active navigators.

   void EndTrack();
     // Signal end of tracking of current track.  
     //   Reset internal state
     //   Inform TransportationManager to use 'ordinary' Navigator

    G4TouchableHandle CreateTouchableHandle( G4int navId ) const;
    inline G4VPhysicalVolume* GetLocatedVolume( G4int navId ) const;

    G4bool RecheckDistanceToCurrentBoundary(
                                   const G4ThreeVector& pGlobalPoint,
                                   const G4ThreeVector& pDirection,
                                   const G4double pCurrentProposedStepLength,
                                   G4double* prDistance,
                                   G4double* prNewSafety = nullptr) const;
   // Trial method for checking potential displacement for MS

   // -----------------------------------------------------------------
  
   inline G4bool IsParticleLooping() const;

   inline G4double GetCurrentSafety() const;
     // Minimum value of safety after last ComputeStep
   inline G4double GetMinimumStep() const;      
     // Get the minimum step size from the last ComputeStep call
     //   - in case full step is taken, this is kInfinity
   inline unsigned int  GetNumberGeometriesLimitingStep() const; 

   G4double ComputeSafety( const G4ThreeVector& globalPoint); 
     // Recompute safety for the relevant point the endpoint of the last step!!
     // Maintain vector of individual safety values (for next method)

   G4double ObtainSafety( G4int navId, G4ThreeVector& globalCenterPoint );
     // Obtain safety for navigator/geometry navId for last point 'computed'
     //   --> last point for which ComputeSafety was called
     //   Returns the point (center) for which this safety is valid

   void EnableParallelNavigation( G4bool enableChoice = true ); 
     // Must call it to ensure that PathFinder is prepared,  
     // especially for curved tracks. If true it switches PropagatorInField
     // to use MultiNavigator. Must call it with false to undo (=PiF use
     // Navigator for tracking!)

   inline G4int  SetVerboseLevel(G4int lev = -1);

 public:  // with description

   inline G4int GetMaxLoopCount() const;
   inline void  SetMaxLoopCount( G4int new_max );
     // A maximum for the number of steps that a (looping) particle can take

 public:  // without description

   inline void MovePoint();
     // Signal that location will be moved -- internal use primarily

   // To provide best compatibility between Coupled and Old Transportation
   // the next two methods are provided:

   G4double LastPreSafety( G4int navId, G4ThreeVector& globalCenterPoint,
                           G4double& minSafety ); 
     // Obtain last safety needed in ComputeStep (for geometry navId)
     // --> last point at which ComputeStep recalculated safety
     //     Returns the point (center) for which this safety is valid
     //     and also the minimum safety over all navigators (i.e. full)

   void PushPostSafetyToPreSafety(); 
     // Tell PathFinder to copy PostStep Safety to PreSafety
     // (for use at next step)

   G4String& LimitedString( ELimited lim );
     // Convert ELimited to string

   ~G4PathFinder();
     // Destructor

 protected:  // without description

   G4double DoNextLinearStep( const G4FieldTrack& FieldTrack,
                                    G4double      proposedStepLength); 

   G4double DoNextCurvedStep( const G4FieldTrack& FieldTrack,
                                    G4double      proposedStepLength,
                                    G4VPhysicalVolume* pCurrentPhysVolume); 

  void WhichLimited();
  void PrintLimited();
    // Print key details out for debugging

  inline G4bool UseSafetyForOptimization( G4bool );
    // Whether use safety to discard unneccesary calls to navigator

  void ReportMove( const G4ThreeVector& OldV,
                   const G4ThreeVector& NewV,
                   const G4String& Quantity ) const;
    // Helper method to report movement (likely of initial point)

 protected:

   G4PathFinder();  //  Singleton 

   inline G4Navigator* GetNavigator(G4int n) const;

 private:

   // ----------------------------------------------------------------------
   //  DATA Members
   // ----------------------------------------------------------------------

   G4MultiNavigator* fpMultiNavigator; 
     // Object that enables G4PropagatorInField to see many geometries

   G4int fNoActiveNavigators = 0; 
   G4bool fNewTrack = false; // Flag a new track (ensure first step)

   static const G4int fMaxNav = 16;

   // Global state (retained during stepping for one track)

   G4Navigator*  fpNavigator[fMaxNav];

   // State changed in a step computation

   ELimited      fLimitedStep[fMaxNav];
   G4bool        fLimitTruth[fMaxNav];
   G4double      fCurrentStepSize[fMaxNav]; 
   G4int fNoGeometriesLimiting = 0;  // How many processes contribute to limit

   G4ThreeVector fPreSafetyLocation;
     // last initial position for which safety evaluated
   G4double      fPreSafetyMinValue = -1.0;
     // - corresponding value of full safety
   G4double      fPreSafetyValues[ fMaxNav ];
     // Safeties for the above point

   // This part of the state can be retained for several calls --> CARE

   G4ThreeVector fPreStepLocation;
     // point where last ComputeStep called
   G4double fMinSafety_PreStepPt = -1.0;
     // - corresponding value of full safety
   G4double fCurrentPreStepSafety[ fMaxNav ];
     // Safeties for the above point.
     // This changes at each step, so it can differ when steps
     // inside min-safety are made

   G4bool fPreStepCenterRenewed = false;
     // Whether PreSafety coincides with PreStep point 

   G4double fMinStep = -1.0;  // As reported by Navigators -- can be kInfinity
   G4double fTrueMinStep = -1.0;  // Corrected in case >= proposed

   // State after calling 'locate'
   //
   G4VPhysicalVolume* fLocatedVolume[fMaxNav];
   G4ThreeVector      fLastLocatedPosition; 

   // State after calling 'ComputeStep'
   // (others member variables will be affected)
   //
   G4FieldTrack fEndState;  // Point, velocity, ... at proposed step end
   G4bool fFieldExertedForce = false; // In current proposed step

   G4bool fRelocatedPoint = false; // Signals that point was or is being moved 
                                   // from the position of the last location or
                                   // the endpoint resulting from ComputeStep()
                                   // -- invalidates fEndState

   // State for 'ComputeSafety' and related methods
   //
   G4ThreeVector fSafetyLocation;
     // point where ComputeSafety is called
   G4double      fMinSafety_atSafLocation = -1.0;
     // - corresponding value of safety
   G4double      fNewSafetyComputed[ fMaxNav ];
     // Safeties for last ComputeSafety

   // State for Step numbers
   //
   G4int fLastStepNo = -1, fCurrentStepNo = -1; 

   G4int fVerboseLevel = 0;  // For debugging purposes

   G4TransportationManager* fpTransportManager; // Cache for frequent use
   G4PropagatorInField* fpFieldPropagator;

   G4double kCarTolerance;

   static G4ThreadLocal G4PathFinder* fpPathFinder;
};

// ********************************************************************
// Inline methods.
// ********************************************************************

inline G4VPhysicalVolume* G4PathFinder::GetLocatedVolume( G4int navId ) const
{
  G4VPhysicalVolume* vol = nullptr;  
  if( (navId < fMaxNav) && (navId >= 0) ) { vol= fLocatedVolume[navId]; }
  return vol; 
}

inline G4int G4PathFinder::SetVerboseLevel(G4int newLevel)
{
  G4int old = fVerboseLevel;
  fVerboseLevel = newLevel;
  return old;
}

inline G4double G4PathFinder::GetMinimumStep() const
{ 
  return fMinStep; 
} 

inline unsigned int G4PathFinder::GetNumberGeometriesLimitingStep() const
{
  unsigned int noGeometries = fNoGeometriesLimiting;
  return noGeometries;
}

inline G4double G4PathFinder::GetCurrentSafety() const
{
  return fMinSafety_PreStepPt;
}

inline void G4PathFinder::MovePoint()
{
  fRelocatedPoint = true;
}

inline G4Navigator* G4PathFinder::GetNavigator(G4int n) const
{ 
  if( (n>fNoActiveNavigators) || (n<0) ) { n=0; }
  return fpNavigator[n];
}

inline G4double
G4PathFinder::ObtainSafety( G4int navId, G4ThreeVector& globalCenterPoint )
{
  globalCenterPoint = fSafetyLocation; 
  return fNewSafetyComputed[ navId ];
}

inline G4double
G4PathFinder::LastPreSafety( G4int navId, G4ThreeVector& globalCenterPoint, 
                             G4double& minSafety )
{
  globalCenterPoint = fPreSafetyLocation;
  minSafety =         fPreSafetyMinValue;
  return  fPreSafetyValues[ navId ];
}

#endif