HelixForwardPlaneCrossing.h

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#ifndef HelixForwardPlaneCrossing_H_
#define HelixForwardPlaneCrossing_H_

#include "DataFormats/TrajectorySeed/interface/PropagationDirection.h"
#include "TrackingTools/GeomPropagators/interface/HelixPlaneCrossing.h"
#include "DataFormats/GeometrySurface/interface/Plane.h"
#include <limits>

class HelixForwardPlaneCrossing final : public HelixPlaneCrossing {
public:
  HelixForwardPlaneCrossing(const PositionType& point,
                const DirectionType& direction,
                const float curvature,
                const PropagationDirection propDir = alongMomentum);
  // destructor
  virtual ~HelixForwardPlaneCrossing() {}

  virtual std::pair<bool,double> pathLength(const Plane& plane) {
    //
    // Protect against p_z=0 and calculate path length
    //
    if unlikely( std::abs(theCosTheta)<std::numeric_limits<float>::min()  )  return std::pair<bool,double>(false,0);
    
    double dS = (plane.position().z()-theZ0) / theCosTheta;
    
    // negative logic to avoid checking for anyDirection...
    return std::make_pair( ! ( 
                  ( (thePropDir==alongMomentum) & (dS<0.) ) |
                  ( (thePropDir==oppositeToMomentum) & (dS>0.) )  
                   ) , dS);

  }

  virtual PositionType position(double s) const;

  virtual DirectionType direction(double s) const;

private:
  //
  // double precision vectors for internal use
  //
  typedef Basic3DVector<double>  PositionTypeDouble;
  typedef Basic3DVector<double>  DirectionTypeDouble;

  const double theX0,theY0,theZ0;
  double theCosPhi0,theSinPhi0;
  double theCosTheta,theSinTheta;
  const double theRho;

  const PropagationDirection thePropDir;

  mutable double theCachedS;
  mutable double theCachedDPhi;
  mutable double theCachedSDPhi;
  mutable double theCachedCDPhi;

  static const float theNumericalPrecision;
};

#endif