/data/refman/pasoursint/CMSSW_5_2_7_hltpatch1/src/TrackingTools/GeomPropagators/src/StraightLinePlaneCrossing.cc

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#include "TrackingTools/GeomPropagators/interface/StraightLinePlaneCrossing.h"

#include "DataFormats/GeometrySurface/interface/Plane.h"

#include <cmath>
#include <cfloat>

StraightLinePlaneCrossing::StraightLinePlaneCrossing(const PositionType& point,
                                                     const DirectionType& momentum,
                                                     const PropagationDirection propDir) :
  theX0(point),
  theP0(momentum.unit()),
  thePropDir(propDir) {
//   cout << "StraightLinePlaneCrossing: x0 = " << point
//        << ", p0 = " << momentum << endl;
}
//
// Propagation status  and path length to intersection
//
std::pair<bool,double>
StraightLinePlaneCrossing::pathLength (const Plane& plane) const {
  //
  // Protect against p_normal=0 and calculate path length
  //
  PositionTypeDouble planePosition(plane.position());
  DirectionTypeDouble planeNormal(plane.normalVector());
//   double pz = plane.localZ(GlobalVector(theP0));
  double pz = planeNormal.dot(theP0);
//   cout << "pz = " << pz << endl;
  if ( fabs(pz)<FLT_MIN )  return std::pair<bool,double>(false,0);
//   double dS = -plane.localZ(GlobalPoint(theX0))/pz;
  double dS = -planeNormal.dot(theX0-planePosition)/pz;
//   if ( thePropDir==alongMomentum )  cout << "alongMomentum ";
//   else if ( thePropDir==oppositeToMomentum )  cout << "oppositeToMomentum ";
//   else  cout << "anyDirection ";
//   cout << dS << endl;
  if ( (thePropDir==alongMomentum && dS<0.) ||
       (thePropDir==oppositeToMomentum && dS>0.) )  return std::pair<bool,double>(false,0);
  //
  // Return result
  //
  return std::pair<bool,double>(true,dS);
}

std::pair<bool,StraightLinePlaneCrossing::PositionType> 
StraightLinePlaneCrossing::position(const Plane& plane) const
{
    std::pair<bool,double> crossed = pathLength(plane);
    if (crossed.first) return std::pair<bool,PositionType>(true, position(crossed.second));
    else return std::pair<bool,PositionType>(false, PositionType());
}