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//
// Class G4BrentLocator
//
// class description:
// 
// Implementing the calculation of the intersection point with a boundary when
// PropagationInField is used. Second order locator based on Brent Method
// for finding the intersection point by means of a 'depth' algorithm in case
// of slow progress (intersection is not found after 100 trials).

// History:
// -------
// 27.10.08 - Tatiana Nikitina: First implementation using
//                              LocateIntersectionPoint() from 
//                              G4PropagatorInField class
// ---------------------------------------------------------------------------

#ifndef G4BRENTLOCATOR_HH
#define G4BRENTLOCATOR_HH

#include "G4VIntersectionLocator.hh"

class G4BrentLocator : public G4VIntersectionLocator
{
  public:  // with description 
 
    G4BrentLocator(G4Navigator *theNavigator);
      // Constructor
    ~G4BrentLocator();
      // Default destructor

    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);     // 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

  private:

    static const G4int max_depth = 4;
    G4FieldTrack* ptrInterMedFT[max_depth+1];
      // Used to store intermediate tracks values in case of too slow progress
};

#endif
