Geant4_10
G4LineSection.cc
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27 // $Id: G4LineSection.cc 66356 2012-12-18 09:02:32Z gcosmo $
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29 // --------------------------------------------------------------------
30 
31 #include "G4LineSection.hh"
32 
34  const G4ThreeVector& PntB )
35  : EndpointA(PntA),
36  VecAtoB(PntB-PntA)
37 {
38  fABdistanceSq = VecAtoB.mag2() ;
39  /*
40  G4double distABsquared = VecAtoB.mag2() ;
41  if ( distABsquared == 0.0)
42  {
43  G4Exception("G4LineSection::G4LineSection()", "GeomField0002",
44  FatalException, "Equal points in input (line->point) ?") ;
45  }
46  else
47  {
48  inverse_square_distAB=1.0 / distABsquared ;
49  }
50  */
51 }
52 
54 {
55  G4double dist_sq;
56  G4ThreeVector VecAZ;
57  G4double sq_VecAZ, inner_prod, unit_projection ;
58 
59  VecAZ= OtherPnt - EndpointA;
60  sq_VecAZ = VecAZ.mag2();
61 
62  inner_prod= VecAtoB.dot( VecAZ );
63 
64  // Determine Projection(AZ on AB) / Length(AB)
65  //
66  if( fABdistanceSq != 0.0 )
67  {
68  // unit_projection= inner_prod * InvsqDistAB();
69  unit_projection = inner_prod/fABdistanceSq;
70 
71  if( (0. <= unit_projection ) && (unit_projection <= 1.0 ) )
72  {
73  dist_sq= sq_VecAZ - unit_projection * inner_prod ;
74  }
75  else
76  {
77  // The perpendicular from the point to the line AB meets the line
78  // in a point outside the line segment!
79 
80  if( unit_projection < 0. ) // A is the closest point
81  {
82  dist_sq= sq_VecAZ;
83  }
84  else // B is the closest point
85  {
86  G4ThreeVector EndpointB = EndpointA + VecAtoB;
87  G4ThreeVector VecBZ = OtherPnt - EndpointB;
88  dist_sq = VecBZ.mag2();
89  }
90  }
91  }
92  else
93  {
94  dist_sq = (OtherPnt - EndpointA).mag2() ;
95  }
96  if( dist_sq < 0.0 ) dist_sq = 0.0 ;
97 
98  return std::sqrt(dist_sq) ;
99 }
100 
102  const G4ThreeVector& LinePntA,
103  const G4ThreeVector& LinePntB )
104 {
105  G4LineSection LineAB( LinePntA, LinePntB ); // Line from A to B
106 
107  return LineAB.Dist( OtherPnt );
108 }
G4double Dist(G4ThreeVector OtherPnt) const
double dot(const Hep3Vector &) const
static G4double Distline(const G4ThreeVector &OtherPnt, const G4ThreeVector &LinePntA, const G4ThreeVector &LinePntB)
G4LineSection(const G4ThreeVector &PntA, const G4ThreeVector &PntB)
double mag2() const
double G4double
Definition: G4Types.hh:76