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G4INCLIntersection.hh
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25 //
26 // INCL++ intra-nuclear cascade model
27 // Alain Boudard, CEA-Saclay, France
28 // Joseph Cugnon, University of Liege, Belgium
29 // Jean-Christophe David, CEA-Saclay, France
30 // Pekka Kaitaniemi, CEA-Saclay, France, and Helsinki Institute of Physics, Finland
31 // Sylvie Leray, CEA-Saclay, France
32 // Davide Mancusi, CEA-Saclay, France
33 //
34 #define INCLXX_IN_GEANT4_MODE 1
35 
36 #include "globals.hh"
37 
45 #ifndef G4INCLINTERSECTION_HH
46 #define G4INCLINTERSECTION_HH 1
47 
48 #include "G4INCLThreeVector.hh"
49 #include <utility>
50 
51 namespace G4INCL {
52 
58  struct Intersection {
59  Intersection(const G4bool e, const G4double t, const ThreeVector &p) :
60  exists(e), time(t), position(p) {}
64  };
65 
66  namespace IntersectionFactory {
67 
100  std::pair<Intersection,Intersection> getTrajectoryIntersections(const ThreeVector &x0, const ThreeVector &p, const G4double r);
101 
102  namespace {
103 
104  Intersection getTrajectoryIntersection(const ThreeVector &x0, const ThreeVector &v, const G4double r, const G4bool earliest) {
105  const G4double scalarVelocity = v.mag();
106  ThreeVector velocityUnitVector = v / scalarVelocity;
107 
108  ThreeVector positionTransverse = x0 - velocityUnitVector * x0.dot(velocityUnitVector);
109  const G4double impactParameter = positionTransverse.mag();
110 
111  const G4double r2 = r*r;
112  G4double distanceZ2 = r2 - impactParameter * impactParameter;
113  if(distanceZ2 < 0.0)
114  return Intersection(false, 0.0, ThreeVector());
115 
116  const G4double distanceZ = std::sqrt(distanceZ2);
117  const ThreeVector position = positionTransverse + velocityUnitVector * (earliest ? -distanceZ : distanceZ);
118  const G4double time = (position-x0).dot(velocityUnitVector)/scalarVelocity;
119  return Intersection(true, time, position);
120  }
121 
122  }
123 
125  return getTrajectoryIntersection(x0, p, r, true);
126  }
127 
129  return getTrajectoryIntersection(x0, p, r, false);
130  }
131 
132  inline std::pair<Intersection,Intersection> getTrajectoryIntersections(const ThreeVector &x0, const ThreeVector &p, const G4double r) {
133  return std::make_pair(
134  getTrajectoryIntersection(x0, p, r, true),
135  getTrajectoryIntersection(x0, p, r, false)
136  );
137  }
138  }
139 
140 }
141 
142 #endif /* G4INCLINTERSECTION_HH */