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25 //
26 // Implementation of G4EnclosingCylinder, a utility class
27 // for a quick check of geometry.
28 //
29 // Author: David C. Williams (davidw@scipp.ucsc.edu)
30 // --------------------------------------------------------------------
31
32 #include "G4EnclosingCylinder.hh"
33 #include "G4PhysicalConstants.hh"
34 #include "G4ReduciblePolygon.hh"
35 #include "G4GeometryTolerance.hh"
36
37 // Constructor
38 //
39 G4EnclosingCylinder::G4EnclosingCylinder( const G4ReduciblePolygon* rz,
40 G4bool thePhiIsOpen,
41 G4double theStartPhi,
42 G4double theTotalPhi )
43 : startPhi(theStartPhi), totalPhi(theTotalPhi),
44 concave(theTotalPhi > pi)
45 {
46 //
47 // Obtain largest r and smallest and largest z
48 //
49 radius = rz->Amax();
50 zHi = rz->Bmax();
51 zLo = rz->Bmin();
52
53 G4double kCarTolerance = G4GeometryTolerance::GetInstance()
54 ->GetSurfaceTolerance();
55 //
56 // Save phi info
57 //
58 phiIsOpen = thePhiIsOpen;
59 if ( phiIsOpen )
60 {
61 rx1 = std::cos(startPhi);
62 ry1 = std::sin(startPhi);
63 dx1 = +ry1*10*kCarTolerance;
64 dy1 = -rx1*10*kCarTolerance;
65
66 rx2 = std::cos(startPhi+totalPhi);
67 ry2 = std::sin(startPhi+totalPhi);
68 dx2 = -ry2*10*kCarTolerance;
69 dy2 = +rx2*10*kCarTolerance;
70 }
71
72 //
73 // Add safety
74 //
75 radius += 10*kCarTolerance;
76 zLo -= 10*kCarTolerance;
77 zHi += 10*kCarTolerance;
78 }
79
80 // Fake default constructor - sets only member data and allocates memory
81 // for usage restricted to object persistency.
82 //
83 G4EnclosingCylinder::G4EnclosingCylinder( __void__& )
84 : radius(0.), zLo(0.), zHi(0.), phiIsOpen(false), startPhi(0.), totalPhi(0.),
85 concave(false)
86 {
87 }
88
89 // Outside
90 //
91 // Decide very rapidly if the point is outside the cylinder
92 //
93 // If one is not certain, return false
94 //
95 G4bool G4EnclosingCylinder::MustBeOutside( const G4ThreeVector& p ) const
96 {
97 if (p.perp() > radius) return true;
98 if (p.z() < zLo) return true;
99 if (p.z() > zHi) return true;
100
101 if (phiIsOpen)
102 {
103 if (concave)
104 {
105 if ( ((p.x()-dx1)*ry1 - (p.y()-dy1)*rx1) < 0) return false;
106 if ( ((p.x()-dx2)*ry2 - (p.y()-dy2)*rx2) > 0) return false;
107 }
108 else
109 {
110 if ( ((p.x()-dx1)*ry1 - (p.y()-dy1)*rx1) > 0) return true;
111 if ( ((p.x()-dx2)*ry2 - (p.y()-dy2)*rx2) < 0) return true;
112 }
113 }
114
115 return false;
116 }
117
118 // Misses
119 //
120 // Decide very rapidly if the trajectory is going to miss the cylinder
121 //
122 // If one is not sure, return false
123 //
124 G4bool G4EnclosingCylinder::ShouldMiss( const G4ThreeVector& p,
125 const G4ThreeVector& v ) const
126 {
127 if (!MustBeOutside(p)) return false;
128
129 G4double cross = p.x()*v.y() - p.y()*v.x();
130 if (cross > radius) return true;
131
132 if (p.perp() > radius)
133 {
134 G4double dot = p.x()*v.x() + p.y()*v.y();
135 if (dot > 0) return true;
136 }
137
138 return false;
139 }
140