| Geant4 Cross Reference |
1 //
2 // ********************************************************************
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24 // ********************************************************************
25 //
26 // G4Field
27 //
28 // Class description:
29 //
30 // Abstract class for any kind of Field.
31 // It allows any kind of field (vector, scalar, tensor and any set of them)
32 // to be defined by implementing the inquiry function interface.
33 //
34 // The key method is GetFieldValue( const double Point[4],
35 // ************* double *fieldArr )
36 // Given an input position/time vector 'Point',
37 // this method must return the value of the field in "fieldArr".
38 //
39 // A field must also specify whether it changes a track's energy:
40 // DoesFieldChangeEnergy()
41 // *********************
42 // A field must co-work with a corresponding Equation of Motion, to
43 // enable the integration of a particle's position, momentum and, optionally,
44 // spin. For this a field and its equation of motion must follow the
45 // same convention for the order of field components in the array "fieldArr"
46
47 // Created: John Apostolakis, 10.03.1997
48 // -------------------------------------------------------------------
49 #ifndef G4FIELD_HH
50 #define G4FIELD_HH
51
52 #include "G4Types.hh"
53 #include "globals.hh"
54
55 class G4Field
56 {
57 public: // with description
58
59 G4Field( G4bool gravityOn = false);
60 G4Field( const G4Field& );
61 virtual ~G4Field();
62 G4Field& operator = (const G4Field& p);
63
64 virtual void GetFieldValue( const G4double Point[4],
65 G4double* fieldArr ) const = 0;
66 // Given the position time vector 'Point',
67 // return the value of the field in the array fieldArr.
68 // Notes:
69 // 1) The 'Point' vector has the following structure:
70 // Point[0] is x ( position, in Geant4 units )
71 // Point[1] is y
72 // Point[2] is z
73 // Point[3] is t ( time, in Geant4 units )
74 // 2) The convention for the components of the field
75 // array 'fieldArr' are determined by the type of field.
76 // See for example the class G4ElectroMagneticField.
77
78 virtual G4bool DoesFieldChangeEnergy() const = 0;
79 // Each type/class of field should respond this accordingly
80 // For example:
81 // - an electric field should return "true"
82 // - a pure magnetic field should return "false"
83
84 inline G4bool IsGravityActive() const;
85 // Does this field include gravity?
86
87 inline void SetGravityActive( G4bool OnOffFlag );
88
89 virtual G4Field* Clone() const;
90 // Implements cloning, needed by multi-threading
91
92 static constexpr G4int MAX_NUMBER_OF_COMPONENTS = 24;
93
94 private:
95
96 G4bool fGravityActive = false;
97 };
98
99 // Inline methods ...
100
101 inline G4bool G4Field::IsGravityActive() const
102 {
103 return fGravityActive;
104 }
105
106 inline void G4Field::SetGravityActive( G4bool OnOffFlag )
107 {
108 fGravityActive = OnOffFlag;
109 }
110
111 #endif
112