G4Navigator.hh

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//
// class G4Navigator
//
// Class description:
//
// A class for use by the tracking management, able to obtain/calculate
// dynamic tracking time information such as the distance to the next volume,
// or to find the physical volume containing a given point in the world
// reference system. The navigator maintains a transformation history and
// other information to optimise the tracking time performance.
 
// - Created.                                  Paul Kent,     Jul 95/96
// - Made Navigator Abstract                   G. Cosmo,      Nov  2003
// - Added check mode                          G. Cosmo,      Mar  2004
// - Zero step protections                     J.A. / G.C.,   Nov  2004
// *********************************************************************
 
#ifndef G4NAVIGATOR_HH
#define G4NAVIGATOR_HH
 
#include "geomdefs.hh"
 
#include "G4ThreeVector.hh"
#include "G4AffineTransform.hh"
#include "G4RotationMatrix.hh"
 
#include "G4LogicalVolume.hh"             // Used in inline methods
#include "G4GRSVolume.hh"                 //    "         "
#include "G4GRSSolid.hh"                  //    "         "
#include "G4TouchableHandle.hh"           //    "         "
#include "G4TouchableHistoryHandle.hh"
 
#include "G4NavigationHistory.hh"
#include "G4NormalNavigation.hh"
#include "G4VoxelNavigation.hh"
#include "G4ParameterisedNavigation.hh"
#include "G4ReplicaNavigation.hh"
#include "G4RegularNavigation.hh"
#include "G4VExternalNavigation.hh"
 
#include <iostream>
 
class G4VPhysicalVolume;
 
class G4Navigator
{
  public:  // with description
 
  friend std::ostream& operator << (std::ostream &os, const G4Navigator &n);
 
  G4Navigator();
    // Constructor - initialisers and setup.
 
  G4Navigator(const G4Navigator&) = delete;
  G4Navigator& operator=(const G4Navigator&) = delete;
    // Copy constructor & assignment operator not allowed.
 
  virtual ~G4Navigator();
    // Destructor. No actions.
 
  virtual G4double ComputeStep(const G4ThreeVector& pGlobalPoint,
                               const G4ThreeVector& pDirection,
                               const G4double pCurrentProposedStepLength,
                                     G4double& pNewSafety);
    // Calculate the distance to the next boundary intersected
    // along the specified NORMALISED vector direction and
    // from the specified point in the global coordinate
    // system. LocateGlobalPointAndSetup or LocateGlobalPointWithinVolume 
    // must have been called with the same global point prior to this call.
    // The isotropic distance to the nearest boundary is also
    // calculated (usually an underestimate). The current
    // proposed Step length is used to avoid intersection
    // calculations: if it can be determined that the nearest
    // boundary is >pCurrentProposedStepLength away, kInfinity
    // is returned together with the computed isotropic safety
    // distance. Geometry must be closed.
 
  G4double CheckNextStep(const G4ThreeVector& pGlobalPoint,
                         const G4ThreeVector& pDirection,
                         const G4double pCurrentProposedStepLength,
                               G4double& pNewSafety); 
    // Same as above, but do not disturb the state of the Navigator.
 
  virtual
  G4VPhysicalVolume* ResetHierarchyAndLocate(const G4ThreeVector& point,
                                             const G4ThreeVector& direction,
                                             const G4TouchableHistory& h);
 
    // Resets the geometrical hierarchy and search for the volumes deepest
    // in the hierarchy containing the point in the global coordinate space.
    // The direction is used to check if a volume is entered.
    // The search begin is the geometrical hierarchy at the location of the
    // last located point, or the endpoint of the previous Step if
    // SetGeometricallyLimitedStep() has been called immediately before.
    // 
    // Important Note: In order to call this the geometry MUST be closed.
 
  virtual
  G4VPhysicalVolume* LocateGlobalPointAndSetup(const G4ThreeVector& point,
                                      const G4ThreeVector* direction = nullptr,
                                      const G4bool pRelativeSearch = true,
                                      const G4bool ignoreDirection = true);
    // Search the geometrical hierarchy for the volumes deepest in the hierarchy
    // containing the point in the global coordinate space. Two main cases are:
    //  i) If pRelativeSearch=false it makes use of no previous/state
    //     information. Returns the physical volume containing the point, 
    //     with all previous mothers correctly set up.
    // ii) If pRelativeSearch is set to true, the search begin is the
    //     geometrical hierarchy at the location of the last located point,
    //     or the endpoint of the previous Step if SetGeometricallyLimitedStep()
    //     has been called immediately before.
    // The direction is used (to check if a volume is entered) if either
    //   - the argument ignoreDirection is false, or
    //   - the Navigator has determined that it is on an edge shared by two or
    //     more volumes.  (This is state information.)
    // 
    // Important Note: In order to call this the geometry MUST be closed.
 
  virtual
  void LocateGlobalPointWithinVolume(const G4ThreeVector& position);
    // Notify the Navigator that a track has moved to the new Global point
    // 'position', that is known to be within the current safety.
    // No check is performed to ensure that it is within  the volume. 
    // This method can be called instead of LocateGlobalPointAndSetup ONLY if
    // the caller is certain that the new global point (position) is inside the
    // same volume as the previous position.  Usually this can be guaranteed
    // only if the point is within safety.
 
  inline void LocateGlobalPointAndUpdateTouchableHandle(
                const G4ThreeVector&       position,
                const G4ThreeVector&       direction,
                      G4TouchableHandle&   oldTouchableToUpdate,
                const G4bool               RelativeSearch = true);
    // First, search the geometrical hierarchy like the above method
    // LocateGlobalPointAndSetup(). Then use the volume found and its
    // navigation history to update the touchable.
 
  inline void LocateGlobalPointAndUpdateTouchable(
                const G4ThreeVector&       position,
                const G4ThreeVector&       direction,
                      G4VTouchable*        touchableToUpdate,
                const G4bool               RelativeSearch = true);
    // First, search the geometrical hierarchy like the above method
    // LocateGlobalPointAndSetup(). Then use the volume found and its
    // navigation history to update the touchable.
 
  inline void LocateGlobalPointAndUpdateTouchable(
                const G4ThreeVector&       position,
                      G4VTouchable*        touchableToUpdate,
                const G4bool               RelativeSearch = true);
    // Same as the method above but missing direction.
 
  inline void SetGeometricallyLimitedStep();
    // Inform the navigator that the previous Step calculated
    // by the geometry was taken in its entirety.
 
  virtual G4double ComputeSafety(const G4ThreeVector& globalpoint,
                                 const G4double pProposedMaxLength = DBL_MAX,
                                 const G4bool keepState = true);
    // Calculate the isotropic distance to the nearest boundary from the
    // specified point in the global coordinate system. 
    // The globalpoint utilised must be within the current volume.
    // The value returned is usually an underestimate.  
    // The proposed maximum length is used to avoid volume safety
    //  calculations.  The geometry must be closed.
    // To ensure minimum side effects from the call, keepState
    //  must be true.
  
   virtual G4bool RecheckDistanceToCurrentBoundary(
                               const G4ThreeVector& pGlobalPoint,
                               const G4ThreeVector& pDirection,
                               const G4double CurrentProposedStepLength,
                                     G4double* prDistance,
                                     G4double* prNewSafety = nullptr) const;
    // Trial method for checking potential displacement for MS
    // Check new Globalpoint, to see whether it is in current volume
    // (mother) and not in potential entering daughter.
    // If in mother, check distance to boundary along pDirection.
    // If in entering daughter, check distance back to boundary. 
    // NOTE:
    // Can be called only after ComputeStep is called - before ReLocation
    // Deals only with current volume (and potentially entered)
 
  inline G4VPhysicalVolume* GetWorldVolume() const;
    // Return the current  world (`topmost') volume.
 
  inline void SetWorldVolume(G4VPhysicalVolume* pWorld);
    // Set the world (`topmost') volume. This must be positioned at
    // origin (0,0,0) and unrotated.
 
  inline G4GRSVolume* CreateGRSVolume() const;
  inline G4GRSSolid* CreateGRSSolid() const; 
  inline G4TouchableHistory* CreateTouchableHistory() const;
  inline G4TouchableHistory* CreateTouchableHistory(const G4NavigationHistory*) const;
    // `Touchable' creation methods: caller has deletion responsibility.
 
  virtual G4TouchableHistoryHandle CreateTouchableHistoryHandle() const;
    // Returns a reference counted handle to a touchable history.
 
  virtual G4ThreeVector GetLocalExitNormal(G4bool* valid);
  virtual G4ThreeVector GetLocalExitNormalAndCheck(const G4ThreeVector& point,
                                                         G4bool* valid);
  virtual G4ThreeVector GetGlobalExitNormal(const G4ThreeVector& point,
                                                  G4bool* valid);
    // Return Exit Surface Normal and validity too.
    // Can only be called if the Navigator's last Step has crossed a
    // volume geometrical boundary.
    // It returns the Normal to the surface pointing out of the volume that
    // was left behind and/or into the volume that was entered.
    // Convention:
    //   The *local* normal is in the coordinate system of the *final* volume.
    // Restriction:
    //   Normals are not available for replica volumes (returns valid= false)
    // These methods takes full care about how to calculate this normal,
    // but if the surfaces are not convex it will return valid=false.
 
  inline G4int GetVerboseLevel() const;
  inline void  SetVerboseLevel(G4int level);
    // Get/Set Verbose(ness) level.
    // [if level>0 && G4VERBOSE, printout can occur]
 
  inline G4bool IsActive() const;
    // Verify if the navigator is active.
  inline void  Activate(G4bool flag);
    // Activate/inactivate the navigator.
 
  inline G4bool EnteredDaughterVolume() const;
    // The purpose of this function is to inform the caller if the track is
    // entering a daughter volume while exiting from the current volume.
    // This method returns 
    // - True only in case 1) above, that is when the Step has caused
    //   the track to arrive at a boundary of a daughter.
    // - False in cases 2), 3) and 4), i.e. in all other cases.
    // This function is not guaranteed to work if SetGeometricallyLimitedStep()
    // was not called when it should have been called.
  inline G4bool ExitedMotherVolume() const;
    // Verify if the step has exited the mother volume.
 
  inline void CheckMode(G4bool mode);
    // Run navigation in "check-mode", therefore using additional
    // verifications and more strict correctness conditions.
    // Is effective only with G4VERBOSE set.
  inline G4bool IsCheckModeActive() const;
  inline void SetPushVerbosity(G4bool mode);
    // Set/unset verbosity for pushed tracks (default is true).
 
  void PrintState() const;
    // Print the internal state of the Navigator (for debugging).
    // The level of detail is according to the verbosity.
 
  inline const G4AffineTransform& GetGlobalToLocalTransform() const;
  inline const G4AffineTransform  GetLocalToGlobalTransform() const;
    // Obtain the transformations Global/Local (and inverse).
    // Clients of these methods must copy the data if they need to keep it.
 
  G4AffineTransform GetMotherToDaughterTransform(G4VPhysicalVolume* dVolume, 
                                                 G4int dReplicaNo,
                                                 EVolume dVolumeType );
    // Obtain mother to daughter transformation
 
  inline void ResetStackAndState();
    // Reset stack and minimum or navigator state machine necessary for reset
    // as needed by LocalGlobalPointAndSetup.
    // [Does not perform clears, resizes, or reset fLastLocatedPointLocal]
 
  inline G4int SeverityOfZeroStepping( G4int* noZeroSteps ) const; 
    // Report on severity of error and number of zero steps,
    // in case Navigator is stuck and is returning zero steps.
    // Values: 1 (small problem),  5 (correcting), 
    //         9 (ready to abandon), 10 (abandoned)
 
  inline G4ThreeVector GetCurrentLocalCoordinate() const;
    // Return the local coordinate of the point in the reference system
    // of its containing volume that was found by LocalGlobalPointAndSetup.
    // The local coordinate of the last located track.
 
  inline G4ThreeVector NetTranslation() const;
  inline G4RotationMatrix NetRotation() const;
    // Compute+return the local->global translation/rotation of current volume.
 
  inline void EnableBestSafety( G4bool value = false );
    // Enable best-possible evaluation of isotropic safety.
 
  inline G4VExternalNavigation* GetExternalNavigation() const;
  inline void SetExternalNavigation(G4VExternalNavigation* externalNav);
    // Accessor & modifier for custom external navigation.
   
  inline G4Navigator* Clone() const;
    // Cloning feature for use in MT applications to clone
    // navigator, including external sub-navigator.
    // Client has responsibility for ownership of returned allocated pointer.
 
 protected:  // with description
 
  void SetSavedState();
    // ( fValidExitNormal, fExitNormal, fExiting, fEntering,
    //   fBlockedPhysicalVolume, fBlockedReplicaNo, fLastStepWasZero);
    // Extended to include:
    // ( fLastLocatedPointLocal, fLocatedOutsideWorld;
    //   fEnteredDaughter, fExitedMother
    //   fPreviousSftOrigin, sPreviousSafety)  Safety Sphere.
 
  void RestoreSavedState();
    // Copy aspects of the state, to enable a non-state changing
    // call to ComputeStep().
  
  virtual void ResetState();
    // Utility method to reset the navigator state machine.
 
  inline G4ThreeVector ComputeLocalPoint(const G4ThreeVector& rGlobPoint) const;
    // Return position vector in local coordinate system, given a position
    // vector in world coordinate system.
 
  inline G4ThreeVector ComputeLocalAxis(const G4ThreeVector& pVec) const;
    // Return the local direction of the specified vector in the reference
    // system of the volume that was found by LocalGlobalPointAndSetup.
    // The Local Coordinates of point in world coordinate system.
 
  inline EVolume VolumeType(const G4VPhysicalVolume *pVol) const;
    // Characterise `type' of volume - normal/replicated/parameterised.
 
  inline EVolume CharacteriseDaughters(const G4LogicalVolume *pLog) const;
    // Characterise daughter of logical volume.
 
  inline G4int GetDaughtersRegularStructureId(const G4LogicalVolume *pLv) const;
    // Get regular structure ID of first daughter
 
  virtual void SetupHierarchy();
    // Renavigate & reset hierarchy described by current history
    // o Reset volumes
    // o Recompute transforms and/or solids of replicated/parameterised
    //   volumes.
 
  G4bool CheckOverlapsIterative(G4VPhysicalVolume* vol);
    // Utility method to trigger overlaps check on a volume with reported
    // overlaps ordered by relevance. Used in ComputeStep() when loopings
    // with zero step are detected.
 
 private:
 
  void ComputeStepLog(const G4ThreeVector& pGlobalpoint,
                             G4double moveLenSq) const;
    // Log and checks for steps larger than the tolerance
 
 protected:  // without description
 
  G4double kCarTolerance, fMinStep, fSqTol;
    // Cached tolerances.
 
  //
  // BEGIN State information
  //
 
  G4NavigationHistory fHistory;
    // Transformation and history of the current path
    // through the geometrical hierarchy.
 
  G4ThreeVector fStepEndPoint;
    // Endpoint of last ComputeStep 
    // can be used for optimisation (e.g. when computing safety).
  G4ThreeVector fLastStepEndPointLocal; 
    // Position of the end-point of the last call to ComputeStep 
    // in last Local coordinates.
 
  G4int fVerbose = 0;
    // Verbose(ness) level  [if > 0, printout can occur].
   
  G4bool fEnteredDaughter;
    // A memory of whether in this Step a daughter volume is entered 
    // (set in Compute & Locate).
    //  After Compute: it expects to enter a daughter
    //  After Locate:  it has entered a daughter
 
  G4bool fExitedMother;
    // A similar memory whether the Step exited current "mother" volume
    // completely, not entering daughter.
 
  G4bool fWasLimitedByGeometry = false;
    // Set true if last Step was limited by geometry.
   
 private:
 
  G4ThreeVector fLastLocatedPointLocal;
    // Position of the last located point relative to its containing volume.
    //  This is coupled with the bool member fLocatedOutsideWorld;
 
  G4ThreeVector fExitNormal;  // Leaving volume normal, in the
                              // volume containing the exited
                              // volume's coordinate system
   //  This is closely coupled with G4bool fValidExitNormal - which 
   //    signals whether we have a (valid) normal for volume we're leaving
   
  G4ThreeVector fGrandMotherExitNormal;  // Leaving volume normal, in its 
                                         // own coordinate system
  G4ThreeVector fExitNormalGlobalFrame;  // Leaving volume normal, in the
                                         // global coordinate system
 
  G4ThreeVector  fPreviousSftOrigin;
  G4double       fPreviousSafety; 
    // Memory of last safety origin & value. Used in ComputeStep to ensure
    // that origin of current Step is in the same volume as the point of the
    // last relocation
 
  G4VPhysicalVolume* fLastMotherPhys = nullptr;
    // Memory of the mother volume during previous step.
    //  Intended use: inform user in case of stuck track.
   
  G4VPhysicalVolume* fBlockedPhysicalVolume;
  G4int fBlockedReplicaNo;
  // Identifies the volume and copy / replica number that is 
  //   blocked (after exiting -- because the exit direction is along the exit normal)
  // or a candidate for entry (after compute step.)
   
  // Count zero steps - as one or two can occur due to changing momentum at
  //                    a boundary or at an edge common between volumes
  //                  - several are likely a problem in the geometry
  //                    description or in the navigation
  //
  G4int fNumberZeroSteps;
    // Number of preceding moves that were Zero. Reset to 0 after finite step
  G4int fActionThreshold_NoZeroSteps = 10;  
    // After this many failed/zero steps, act (push etc) 
  G4int fAbandonThreshold_NoZeroSteps = 25; 
    // After this many failed/zero steps, abandon track
 
  G4bool fActive = false;
    // States if the navigator is activated or not.
 
  G4bool fLastTriedStepComputation = false; 
    // Whether ComputeStep was called since the last call to a Locate method
    // Uses: - distinguish parts of state which differ before/after calls
    //         to ComputeStep or one of the Locate methods;
    //       - avoid two consecutive calls to compute-step (illegal).
 
  G4bool fEntering,fExiting;
    // Entering/Exiting volumes blocking/setup
    // o If exiting
    //      volume ptr & replica number (set & used by Locate..())
    //      used for blocking on redescent of geometry
    // o If entering
    //      volume ptr & replica number (set by ComputeStep(),used by
    //      Locate..()) of volume for `automatic' entry
   
  G4bool fValidExitNormal;    // Set true if have leaving volume normal
  G4bool fLastStepWasZero;
    // Whether the last ComputeStep moved Zero. Used to check for edges.
  G4bool fLocatedOnEdge;       
    // Whether the Navigator has detected an edge
  G4bool        fLocatedOutsideWorld;
    // Whether the last call to Locate methods left the world
   
  G4bool  fChangedGrandMotherRefFrame;   // Whether frame is changed   
  G4bool  fCalculatedExitNormal;  // Has it been computed since
                                  // the last call to ComputeStep
                                  // Covers both Global and GrandMother
  //
  // END State information
  //
 
  // Optional State information (created/used as needed)
  // 
   
  // Save key state information (NOT the navigation history stack)
  //
  struct G4SaveNavigatorState
  { 
     G4ThreeVector sExitNormal;  
     G4bool sValidExitNormal;    
     G4bool sEntering, sExiting;
     G4VPhysicalVolume* spBlockedPhysicalVolume;
     G4int sBlockedReplicaNo;  
     G4int sLastStepWasZero; 
     G4bool sWasLimitedByGeometry;
 
     //  Potentially relevant
     //
     G4bool sLocatedOutsideWorld;
     G4ThreeVector sLastLocatedPointLocal; 
     G4bool sEnteredDaughter, sExitedMother;
     G4ThreeVector sPreviousSftOrigin;
     G4double sPreviousSafety; 
  } fSaveState; 
 
private: 
  // BEGIN -- Tracking Invariants
  // ===========================================
  G4VPhysicalVolume* fTopPhysical = nullptr;
    // A link to the topmost physical volume in the detector.
    // Must be positioned at the origin and unrotated.
 
  // Helpers/Utility classes
  //
  G4NormalNavigation fnormalNav;
  G4VoxelNavigation fvoxelNav;
  G4ParameterisedNavigation fparamNav;
  G4ReplicaNavigation freplicaNav;
  G4RegularNavigation fregularNav;
  G4VExternalNavigation* fpExternalNav = nullptr;
  G4VoxelSafety* fpVoxelSafety;
 
  // Utility information
  //
  G4bool fCheck = false;
    // Check-mode flag  [if true, more strict checks are performed].
  G4bool fPushed = false, fWarnPush = true;
    // Push flags  [if true, means a stuck particle has been pushed].
 
  // End -- Tracking Invariants
};
 
#include "G4Navigator.icc"
 
#endif
 
 
// NOTES:
//
// The following methods provide detailed information when a Step has
// arrived at a geometrical boundary.  They distinguish between the different
// causes that can result in the track leaving its current volume.
//
// Four cases are possible:
//
// 1) The particle has reached a boundary of a daughter of the current volume:
//     (this could cause the relocation to enter the daughter itself
//     or a potential granddaughter or further descendant)
//     
// 2) The particle has reached a boundary of the current
//     volume, exiting into a mother (regardless the level
//     at which it is located in the tree):
//
// 3) The particle has reached a boundary of the current
//     volume, exiting into a volume which is not in its
//     parental hierarchy:
//
// 4) The particle is not on a boundary between volumes:
//     the function returns an exception, and the caller is
//     reccomended to compare the G4touchables associated
//     to the preStepPoint and postStepPoint to handle this case.
//
//   G4bool        EnteredDaughterVolume()
//   G4bool        IsExitNormalValid()
//   G4ThreeVector GetLocalExitNormal()
//
// The expected usefulness of these methods is to allow the caller to
// determine how to compute the surface normal at the volume boundary. The two
// possibilities are to obtain the normal from:
//
//   i) the solid associated with the volume of the initial point of the Step.
//      This is valid for cases 2 and 3.  
//      (Note that the initial point is generally the PreStepPoint of a Step).
//   or
// 
//  ii) the solid of the final point, ie of the volume after the relocation.
//      This is valid for case 1.
//      (Note that the final point is generally the PreStepPoint of a Step).
//
// This way the caller can always get a valid normal, pointing outside
// the solid for which it is computed, that can be used at his own
// discretion.