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G4GeomTools.hh
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25 //
26 // G4GeomTools
27 //
28 // Class description:
29 //
30 // A collection of utilities which can be helpfull for a wide range
31 // of geometry-related tasks
32 
33 // 10.10.2016, E.Tcherniaev: Initial version.
34 // --------------------------------------------------------------------
35 #ifndef G4GEOMTOOLS_HH
36 #define G4GEOMTOOLS_HH
37 
38 #include <vector>
39 #include "G4TwoVector.hh"
40 #include "G4ThreeVector.hh"
41 
42 using G4TwoVectorList = std::vector<G4TwoVector>;
43 using G4ThreeVectorList = std::vector<G4ThreeVector>;
44 
45 class G4GeomTools
46 {
47  public:
48 
49  // ==================================================================
50  // 2D Utilities
51  // ------------------------------------------------------------------
52 
53  static G4double TriangleArea(G4double Ax, G4double Ay,
54  G4double Bx, G4double By,
55  G4double Cx, G4double Cy);
56 
57  static G4double TriangleArea(const G4TwoVector& A,
58  const G4TwoVector& B,
59  const G4TwoVector& C);
60  // Calculate area of 2D triangle, return value is positive if
61  // vertices of the triangle are given in anticlockwise order,
62  // otherwise it is negative
63 
64  static G4double QuadArea(const G4TwoVector& A,
65  const G4TwoVector& B,
66  const G4TwoVector& C,
67  const G4TwoVector& D);
68  // Calculate area of 2D quadrilateral, return value is positive if
69  // vertices of the quadrilateral are given in anticlockwise order,
70  // otherwise it is negative
71 
72  static G4double PolygonArea(const G4TwoVectorList& polygon);
73  // Calculate area of 2D polygon, return value is positive if
74  // vertices of the polygon are defined in anticlockwise order,
75  // otherwise it is negative
76 
77  static G4bool PointInTriangle(G4double Px, G4double Py,
78  G4double Ax, G4double Ay,
79  G4double Bx, G4double By,
80  G4double Cx, G4double Cy);
81  // Decide if point (Px,Py) is inside triangle (Ax,Ay)(Bx,By)(Cx,Cy)
82 
83  static G4bool PointInTriangle(const G4TwoVector& P,
84  const G4TwoVector& A,
85  const G4TwoVector& B,
86  const G4TwoVector& C);
87  // Decide if point P is inside triangle ABC
88 
89  static G4bool PointInPolygon(const G4TwoVector& P,
90  const G4TwoVectorList& Polygon);
91  // Decide if point P is inside Polygon
92 
93  static G4bool IsConvex(const G4TwoVectorList& polygon);
94  // Decide if 2D polygon is convex, i.e. all internal angles are
95  // less than pi
96 
97  static G4bool TriangulatePolygon(const G4TwoVectorList& polygon,
98  G4TwoVectorList& result);
99 
100  static G4bool TriangulatePolygon(const G4TwoVectorList& polygon,
101  std::vector<G4int>& result);
102  // Simple implementation of "ear clipping" algorithm for
103  // triangulation of a simple contour/polygon, it places results
104  // in a std::vector as triplets of vertices. If triangulation
105  // is sucsessfull then the function returns true, otherwise false
106 
107  static void RemoveRedundantVertices(G4TwoVectorList& polygon,
108  std::vector<G4int>& iout,
109  G4double tolerance = 0.0);
110  // Remove collinear and coincident points from 2D polygon.
111  // Indices of removed points are available in iout.
112 
113  static G4bool DiskExtent(G4double rmin, G4double rmax,
114  G4double startPhi, G4double delPhi,
115  G4TwoVector& pmin, G4TwoVector& pmax);
116  // Calculate bounding rectangle of a disk sector,
117  // it returns false if input parameters do not meet the following:
118  // rmin >= 0
119  // rmax > rmin + kCarTolerance
120  // delPhi > 0 + kCarTolerance
121 
122  static void DiskExtent(G4double rmin, G4double rmax,
123  G4double sinPhiStart, G4double cosPhiStart,
124  G4double sinPhiEnd, G4double cosPhiEnd,
125  G4TwoVector& pmin, G4TwoVector& pmax);
126  // Calculate bounding rectangle of a disk sector,
127  // faster version without check of parameters
128 
129  static G4double EllipsePerimeter(G4double a,
130  G4double b);
131  // Compute the circumference (perimeter) of an ellipse
132 
133  static G4double EllipticConeLateralArea(G4double a,
134  G4double b,
135  G4double h);
136  // Compute the lateral surface area of an elliptic cone
137 
138  // ==================================================================
139  // 3D Utilities
140  // ------------------------------------------------------------------
141 
142  static G4ThreeVector TriangleAreaNormal(const G4ThreeVector& A,
143  const G4ThreeVector& B,
144  const G4ThreeVector& C);
145  // Find the normal to the plane of 3D triangle ABC,
146  // length of the normal is equal to the area of the triangle
147 
148  static G4ThreeVector QuadAreaNormal(const G4ThreeVector& A,
149  const G4ThreeVector& B,
150  const G4ThreeVector& C,
151  const G4ThreeVector& D);
152  // Find normal to the plane of 3D quadrilateral ABCD,
153  // length of the normal is equal to the area of the quadrilateral
154 
155  static G4ThreeVector PolygonAreaNormal(const G4ThreeVectorList& polygon);
156  // Find normal to the plane of 3D polygon
157  // length of the normal is equal to the area of the polygon
158 
159  /*
160  static G4bool IsPlanar(const G4ThreeVector& A,
161  const G4ThreeVector& B,
162  const G4ThreeVector& C,
163  const G4ThreeVector& D);
164  // Decide if 3D quadrilateral ABCD is planar
165 
166  static G4bool IsPlanar(const G4ThreeVectorList& polygon
167  const G4ThreeVector& normal);
168  // Decide if 3D polygon is planar
169  */
170 
171  static G4double DistancePointSegment(const G4ThreeVector& P,
172  const G4ThreeVector& A,
173  const G4ThreeVector& B);
174  // Calculate distance between point P and line segment AB in 3D
175 
176  static G4ThreeVector ClosestPointOnSegment(const G4ThreeVector& P,
177  const G4ThreeVector& A,
178  const G4ThreeVector& B);
179  // Find point on 3D line segment AB closest to point P
180 
181  static G4ThreeVector ClosestPointOnTriangle(const G4ThreeVector& P,
182  const G4ThreeVector& A,
183  const G4ThreeVector& B,
184  const G4ThreeVector& C);
185  // Find point on 3D triangle ABC closest to point P
186 
187  static G4bool SphereExtent(G4double rmin, G4double rmax,
188  G4double startTheta, G4double delTheta,
189  G4double startPhi, G4double delPhi,
190  G4ThreeVector& pmin, G4ThreeVector& pmax);
191  // Calculate bounding box of a spherical sector,
192  // it returns false if input parameters do not meet the following:
193  // rmin >= 0
194  // rmax > rmin + kCarTolerance
195  // startTheta >= 0 && <= pi;
196  // delTheta > 0 + kCarTolerance
197  // delPhi > 0 + kCarTolerance
198 
199  private:
200 
201  static G4bool CheckSnip(const G4TwoVectorList& contour,
202  G4int a, G4int b, G4int c,
203  G4int n, const G4int* V);
204  // Helper function for TriangulatePolygon()
205 
206  static G4double comp_ellint_2(G4double e);
207  // Complete Elliptic Integral of the Second Kind
208 };
209 
210 #endif // G4GEOMTOOLS_HH