//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
// $Id: G4VIntersectionLocator.icc,v 1.3 2008/11/14 18:26:35 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-02-cand-01 $
//
//
// Class G4VIntersectionLocator inline methods
//
// 27.10.07 - John Apostolakis, Tatiana Nikitina
// ---------------------------------------------------------------------------

inline G4double G4VIntersectionLocator::GetDeltaIntersectionFor()
{
  return fiDeltaIntersection;
} 

inline G4double G4VIntersectionLocator::GetEpsilonStepFor()
{
  return fiEpsilonStep;
}

inline G4Navigator* G4VIntersectionLocator::GetNavigatorFor()
{
  return fiNavigator;
}

inline G4ChordFinder* G4VIntersectionLocator::GetChordFinderFor()
{
  return fiChordFinder;
}

inline G4int G4VIntersectionLocator::GetVerboseFor()
{
  return fVerboseLevel;
}

inline G4bool G4VIntersectionLocator::GetAdjustementOfFoundIntersection()
{
  return fUseNormalCorrection;
}

inline void G4VIntersectionLocator::
AddAdjustementOfFoundIntersection(G4bool UseCorrection )
{
  fUseNormalCorrection=UseCorrection;
}

inline void G4VIntersectionLocator::SetEpsilonStepFor( G4double EpsilonStep )
{
  fiEpsilonStep=EpsilonStep;
}

inline void G4VIntersectionLocator::
SetDeltaIntersectionFor( G4double deltaIntersection )
{
  fiDeltaIntersection=deltaIntersection;
}

inline void G4VIntersectionLocator::SetNavigatorFor( G4Navigator *fNavigator )
{
  fiNavigator=fNavigator;
}

inline void G4VIntersectionLocator::SetChordFinderFor(G4ChordFinder *fCFinder )
{
  fiChordFinder=fCFinder;
}

inline void G4VIntersectionLocator::SetSafetyParametersFor(G4bool UseSafety )
{
  fiUseSafety=UseSafety;
}

inline void G4VIntersectionLocator::SetVerboseFor(G4int fVerbose)
{
  fVerboseLevel=fVerbose;
}

inline G4bool
G4VIntersectionLocator::IntersectChord( G4ThreeVector  StartPointA, 
                                        G4ThreeVector  EndPointB,
                                        G4double      &NewSafety,
                                        G4double      &fPreviousSafety,
                                        G4ThreeVector &fPreviousSftOrigin,
                                        G4double      &LinearStepLength,
                                        G4ThreeVector &IntersectionPoint )
{
  // Calculate the direction and length of the chord AB

  G4ThreeVector  ChordAB_Vector = EndPointB - StartPointA;
  G4double       ChordAB_Length = ChordAB_Vector.mag();  // Magnitude (norm)
  G4ThreeVector  ChordAB_Dir =    ChordAB_Vector.unit();
  G4bool intersects;
  G4ThreeVector OriginShift = StartPointA -  fPreviousSftOrigin ;
  G4double      MagSqShift  = OriginShift.mag2() ;
  G4double      currentSafety;
  G4bool        doCallNav= false;

  if( MagSqShift >= sqr(fPreviousSafety) )
  {
    currentSafety = 0.0 ;
  }
  else
  {
    currentSafety = fPreviousSafety - std::sqrt(MagSqShift) ;
  }

  if( fiUseSafety && (ChordAB_Length <= currentSafety) )
  {
    // The Step is guaranteed to be taken

    LinearStepLength = ChordAB_Length;
    intersects = false;
    NewSafety= currentSafety;
  }
  else
  {
    doCallNav= true; 
      // Check whether any volumes are encountered by the chord AB

    LinearStepLength = GetNavigatorFor()->ComputeStep( StartPointA,
                                 ChordAB_Dir, ChordAB_Length, NewSafety );
    intersects = (LinearStepLength <= ChordAB_Length); 

       // G4Navigator contracts to return k_infinity if len==asked
       // and it did not find a surface boundary at that length

    LinearStepLength = std::min( LinearStepLength, ChordAB_Length);

    // Save the last calculated safety!

    fPreviousSftOrigin = StartPointA;
    fPreviousSafety= NewSafety;

    if( intersects )
    {
       // Intersection Point of chord AB and either volume A's surface 
       //                                or a daughter volume's surface ..
       IntersectionPoint = StartPointA + LinearStepLength * ChordAB_Dir;
    }
  }
  return intersects;
}