include/Geant4/G4Field.hh

0001 //
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0003 // * License and Disclaimer                                           *
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0025 //
0026 // G4Field
0027 //
0028 // Class description:
0029 //
0030 // Abstract class for any kind of Field.
0031 // It allows any kind of field (vector, scalar, tensor and any set of them)
0032 // to be defined by implementing the inquiry function interface.
0033 //
0034 // The key method is  GetFieldValue( const  double Point[4],
0035 //                    *************         double *fieldArr )
0036 // Given an input position/time vector 'Point',
0037 // this method must return the value of the field in "fieldArr".
0038 //
0039 // A field must also specify whether it changes a track's energy:
0040 //                    DoesFieldChangeEnergy()
0041 //                    *********************
0042 // A field must co-work with a corresponding Equation of Motion, to
0043 // enable the integration of a particle's position, momentum and, optionally,
0044 // spin.  For this a field and its equation of motion must follow the
0045 // same convention for the order of field components in the array "fieldArr"
0046
0047 // Created: John Apostolakis, 10.03.1997
0048 // -------------------------------------------------------------------
0049 #ifndef G4FIELD_HH
0050 #define G4FIELD_HH
0051
0052 #include "G4Types.hh"
0053 #include "globals.hh"
0054
0055 class G4Field
0056 {
0057   public:  // with description
0058
0059       G4Field( G4bool gravityOn = false);
0060       G4Field( const G4Field& );
0061       virtual ~G4Field();
0062       G4Field& operator = (const G4Field& p);
0063
0064       virtual void GetFieldValue( const G4double Point[4],
0065                                         G4double* fieldArr ) const = 0;
0066        // Given the position time vector 'Point',
0067        // return the value of the field in the array fieldArr.
0068        //  Notes:
0069        //   1) The 'Point' vector has the following structure:
0070        //        Point[0]  is  x  ( position, in Geant4 units )
0071        //        Point[1]  is  y
0072        //        Point[2]  is  z
0073        //        Point[3]  is  t  ( time,  in Geant4 units )
0074        //   2) The convention for the components of the field
0075        //      array 'fieldArr' are determined by the type of field.
0076        //      See for example the class G4ElectroMagneticField.
0077
0078       virtual G4bool DoesFieldChangeEnergy() const = 0;
0079         // Each type/class of field should respond this accordingly
0080         // For example:
0081         //   - an electric field     should return "true"
0082         //   - a pure magnetic field should return "false"
0083
0084       inline G4bool IsGravityActive() const;
0085         //  Does this field include gravity?
0086
0087       inline void SetGravityActive( G4bool OnOffFlag );
0088
0089       virtual G4Field* Clone() const;
0090         // Implements cloning, needed by multi-threading
0091
0092       static constexpr G4int MAX_NUMBER_OF_COMPONENTS = 24;
0093
0094   private:
0095
0096       G4bool fGravityActive = false;
0097 };
0098
0099 // Inline methods ...
0100
0101 inline G4bool G4Field::IsGravityActive() const
0102 {
0103   return fGravityActive;
0104 }
0105
0106 inline void G4Field::SetGravityActive( G4bool OnOffFlag )
0107 {
0108   fGravityActive = OnOffFlag;
0109 }
0110
0111 #endif