//
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//
// Author:    Stephen Peterson          - swpeters@mdanderson.org
//            MD Anderson Cancer Center - Department of Radiation Physics
//            1515 Holcombe Blvd #94    - Houston, TX  77030
// Comments:  Model of scanning proton beam at MD Anderson PTC-H
//
// ********************************************************************

// General libraries
#include "G4FieldManager.hh"
#include "G4ChordFinder.hh"
#include "G4Mag_UsualEqRhs.hh"
#include "G4MagIntegratorStepper.hh"
#include "G4ClassicalRK4.hh"
#include "G4SystemOfUnits.hh"

// Specific libraries
#include "MagneticField.hh"

// ***************************************************************************************
MagneticField::MagneticField():G4UniformMagField(G4ThreeVector())
// ---------------------------------------------------------------------------------------
{
 // Initializing Magnetic Field
    G4Mag_UsualEqRhs* thisEquation = new G4Mag_UsualEqRhs(this);
    G4MagIntegratorStepper* thisStepper = new G4ClassicalRK4(thisEquation);
    G4ChordFinder* thisChordFinder = new G4ChordFinder(this, 0.01*mm, thisStepper);
    theFieldManager = new G4FieldManager(this, thisChordFinder);
}

// ***************************************************************************************
MagneticField::MagneticField(G4ThreeVector fieldVector):G4UniformMagField(fieldVector)
// ---------------------------------------------------------------------------------------
{
 // Initializing Magnetic Field
    G4Mag_UsualEqRhs* thisEquation = new G4Mag_UsualEqRhs(this);
    G4MagIntegratorStepper* thisStepper = new G4ClassicalRK4(thisEquation);
    G4ChordFinder* thisChordFinder = new G4ChordFinder(this, 0.01*mm, thisStepper);
    theFieldManager = new G4FieldManager(this, thisChordFinder);
}

// Set the value of the Magnetic Field
// ***************************************************************************************
void MagneticField::SetFieldValue(G4ThreeVector fieldVector) 
// ---------------------------------------------------------------------------------------
{   
    if(fieldVector!=G4ThreeVector(0.,0.,0.))
    { 
	G4UniformMagField::SetFieldValue(fieldVector);
	theFieldManager->SetDetectorField(this);
    } else {
	// If the new field's value is Zero, then it is best to insure 
        //   that it is not used for propagation.
	G4MagneticField* magField = NULL;
	theFieldManager->SetDetectorField(magField);
    }
}

// ***************************************************************************************
MagneticField::~MagneticField()
// ---------------------------------------------------------------------------------------
{
    // GetGlobalFieldManager()->SetDetectorField(0);
}

// ***************************************************************************************
G4FieldManager*  MagneticField::GetTheFieldManager()
// ---------------------------------------------------------------------------------------
{
    return theFieldManager;
}

// ***************************************************************************************