Gabriele Cosmo
289 lines
11 KiB
C++
289 lines
11 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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//
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//
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// John Allison 17th August 2013
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// Model that knows how to draw the magnetic field.
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#include "G4MagneticFieldModel.hh"
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#include "G4VGraphicsScene.hh"
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#include "G4TransportationManager.hh"
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#include "G4FieldManager.hh"
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#include "G4Field.hh"
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#include "G4Colour.hh"
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#include "G4VPhysicalVolume.hh"
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#include "G4ArrowModel.hh"
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#include "G4Polyline.hh"
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#include "G4VisAttributes.hh"
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#include "G4SystemOfUnits.hh"
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#include <sstream>
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#include <limits>
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#include <vector>
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G4MagneticFieldModel::~G4MagneticFieldModel () {}
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G4MagneticFieldModel::G4MagneticFieldModel
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(G4int nDataPointsPerMaxHalfScene,
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Representation representation,
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G4int arrow3DLineSegmentsPerCircle)
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: fNDataPointsPerMaxHalfScene(nDataPointsPerMaxHalfScene)
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, fRepresentation(representation)
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, fArrow3DLineSegmentsPerCircle(arrow3DLineSegmentsPerCircle)
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{
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fType = "G4MagneticFieldModel";
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fGlobalTag = fType;
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std::ostringstream oss;
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oss << ':' << fNDataPointsPerMaxHalfScene
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<< ':' << fArrow3DLineSegmentsPerCircle;
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if (fRepresentation == Representation::fullArrow) {
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oss << " full arrow";
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} else if (fRepresentation == Representation::lightArrow) {
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oss << " light arrow";
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}
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fGlobalDescription = fType + oss.str();
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}
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void G4MagneticFieldModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
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{
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// G4cout << "G4MagneticFieldModel::DescribeYourselfTo" << G4endl;
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const G4VisExtent& extent = sceneHandler.GetExtent();
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const G4double xMin = extent.GetXmin();
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const G4double yMin = extent.GetYmin();
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const G4double zMin = extent.GetZmin();
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const G4double xMax = extent.GetXmax();
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const G4double yMax = extent.GetYmax();
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const G4double zMax = extent.GetZmax();
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const G4double xHalfScene = 0.5 * (xMax - xMin);
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const G4double yHalfScene = 0.5 * (yMax - yMin);
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const G4double zHalfScene = 0.5 * (zMax - zMin);
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const G4double xSceneCentre = 0.5 * (xMax + xMin);
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const G4double ySceneCentre = 0.5 * (yMax + yMin);
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const G4double zSceneCentre = 0.5 * (zMax + zMin);
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const G4double maxHalfScene =
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std::max(xHalfScene,std::max(yHalfScene,zHalfScene));
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if (maxHalfScene <= 0.) {
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G4cout
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<< "Extent non-positive."
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<< G4endl;
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return;
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}
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G4TransportationManager* tMgr =
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G4TransportationManager::GetTransportationManager();
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assert(tMgr);
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G4Navigator* navigator = tMgr->GetNavigatorForTracking();
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assert(navigator);
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G4FieldManager* globalFieldMgr = tMgr->GetFieldManager();
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const G4Field* globalField = 0;
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const G4String intro = "G4MagneticFieldModel::DescribeYourselfTo: ";
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if (globalFieldMgr) {
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if (globalFieldMgr->DoesFieldExist()) {
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globalField = globalFieldMgr->GetDetectorField();
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if (!globalField) {
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static G4bool warned = false;
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if (!warned) {
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G4cout << intro
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<< "Null global field pointer."
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<< G4endl;
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warned = true;
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}
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}
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}
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} else {
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static G4bool warned = false;
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if (!warned) {
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G4cout << intro
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<< "No global field manager."
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<< G4endl;
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warned = true;
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}
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}
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// Constants
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const G4double interval = maxHalfScene / fNDataPointsPerMaxHalfScene;
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const G4int nDataPointsPerXHalfScene = G4int(xHalfScene / interval);
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const G4int nDataPointsPerYHalfScene = G4int(yHalfScene / interval);
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const G4int nDataPointsPerZHalfScene = G4int(zHalfScene / interval);
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const G4int nXSamples = 2 * nDataPointsPerXHalfScene + 1;
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const G4int nYSamples = 2 * nDataPointsPerYHalfScene + 1;
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const G4int nZSamples = 2 * nDataPointsPerZHalfScene + 1;
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const G4int nSamples = nXSamples * nYSamples * nZSamples;
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const G4int nSamples3 = nSamples * 3;
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const G4double arrowLengthMax = 0.8 * interval;
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const G4int nResults = 6; // 3 B-field + 3 E-field.
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// Working space for GetFieldValue.
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double position_time[4] = {0,0,0,0};
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double result[nResults];
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// Working vectors for field values, etc.
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std::vector<G4double> BField(nSamples3); // Initialises to zero.
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std::vector<G4double> BFieldMagnitude(nSamples); // Initialises to zero.
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std::vector<G4double> xyz(nSamples3); // Initialises to zero.
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// Get field values and ascertain maximum field.
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G4double BFieldMagnitudeMax = -std::numeric_limits<G4double>::max();
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for (G4int i = 0; i < nXSamples; i++) {
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G4double x = xSceneCentre + (i - nDataPointsPerXHalfScene) * interval;
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position_time[0] = x;
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for (G4int j = 0; j < nYSamples; j++) {
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G4double y = ySceneCentre + (j - nDataPointsPerYHalfScene) * interval;
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position_time[1] = y;
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for (G4int k = 0; k < nZSamples; k++) {
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G4double z = zSceneCentre + (k - nDataPointsPerZHalfScene) * interval;
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position_time[2] = z;
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// Calculate indices into working vectors
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const G4int ijk = i * nYSamples * nZSamples + j * nZSamples + k;
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const G4int ijk3 = ijk * 3;
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// Find volume at this location.
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G4ThreeVector pos(x,y,z);
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const G4VPhysicalVolume* pPV =
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navigator->LocateGlobalPointAndSetup(pos,0,false,true);
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const G4Field* field = globalField;
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if (pPV) {
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// Get logical volume.
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const G4LogicalVolume* pLV = pPV->GetLogicalVolume();
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if (pLV) {
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// Value for Region, if any, overrides
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G4Region* pRegion = pLV->GetRegion();
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if (pRegion) {
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G4FieldManager* pRegionFieldMgr = pRegion->GetFieldManager();
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if (pRegionFieldMgr) {
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field = pRegionFieldMgr->GetDetectorField();
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// G4cout << "Region with field" << G4endl;
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}
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}
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// 'Local' value from logical volume, if any, overrides
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G4FieldManager* pLVFieldMgr = pLV->GetFieldManager();
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if (pLVFieldMgr) {
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field = pLVFieldMgr->GetDetectorField();
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// G4cout << "Logical volume with field" << G4endl;
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}
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}
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}
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// If field found, get values and store in working vectors.
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if (field) {
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// Get field values in result array.
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field->GetFieldValue(position_time,result);
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// G4cout
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// << "BField/T:"
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// << " " << result[0]/tesla
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// << " " << result[1]/tesla
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// << " " << result[2]/tesla
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// << G4endl;
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// Store B-field components.
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for (G4int l = 0; l < 3; l++) {
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BField[ijk3 + l] = result[l];
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}
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// Calculate magnitude and store.
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G4double mag = sqrt
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(result[0]*result[0]+result[1]*result[1]+result[2]*result[2]);
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BFieldMagnitude[ijk] = mag;
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// Store position.
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xyz[ijk3] = x;
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xyz[ijk3 + 1] = y;
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xyz[ijk3 + 2] = z;
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// Find maximum field magnitude.
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if (mag > BFieldMagnitudeMax) {
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BFieldMagnitudeMax = mag;
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}
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}
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}
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}
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}
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if (BFieldMagnitudeMax <= 0) {
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G4cout
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<< "No field in this scene."
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<< G4endl;
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return;
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}
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if (fRepresentation == Representation::lightArrow) sceneHandler.BeginPrimitives();
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for (G4int i = 0; i < nSamples; i++) {
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if (BFieldMagnitude[i] > 0) {
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const G4int i3 = i * 3;
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// Field (Bx,By,Bz) at (x,y,z).
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const G4double Bx = BField[i3];
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const G4double By = BField[i3 + 1];
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const G4double Bz = BField[i3 + 2];
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const G4double x = xyz[i3];
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const G4double y = xyz[i3 + 1];
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const G4double z = xyz[i3 + 2];
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const G4double B = BFieldMagnitude[i];
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// G4cout
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// << "Position/mm, BField/T unpacked:"
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// << ' ' << x/mm
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// << ' ' << y/mm
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// << ' ' << z/mm
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// << " " << Bx/tesla
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// << " " << By/tesla
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// << " " << Bz/tesla
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// << G4endl;
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if (B > 0.) {
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const G4double f = B / BFieldMagnitudeMax;
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G4double red = 0., green = 0., blue = 0., alpha = 1.;
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if (f < 0.5) { // Linear colour scale: 0->0.5->1 is blue->green->red.
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green = 2. * f;
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blue = 2. * (0.5 - f);
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} else {
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red = 2. * (f - 0.5);
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green = 2. * (1.0 - f);
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}
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const G4Colour arrowColour(red,green,blue,alpha);
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const G4double arrowLength = arrowLengthMax * f;
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// Base of arrow is at (x,y,z).
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const G4double& x1 = x;
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const G4double& y1 = y;
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const G4double& z1 = z;
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// Head of arrow depends on field direction and strength.
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const G4double x2 = x1 + arrowLength * Bx / B;
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const G4double y2 = y1 + arrowLength * By / B;
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const G4double z2 = z1 + arrowLength * Bz / B;
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if (fRepresentation == Representation::fullArrow) {
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G4ArrowModel BArrow(x1,y1,z1,x2,y2,z2,arrowLength/5,arrowColour,
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"BField",
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fArrow3DLineSegmentsPerCircle);
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BArrow.DescribeYourselfTo(sceneHandler);
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} else if (fRepresentation == Representation::lightArrow) {
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G4Polyline BArrowLite;
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G4VisAttributes va(arrowColour);
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BArrowLite.SetVisAttributes(va);
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BArrowLite.push_back(G4Point3D(x1,y1,z1));
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BArrowLite.push_back(G4Point3D(x2,y2,z2));
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sceneHandler.AddPrimitive(BArrowLite);
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}
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}
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}
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}
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if (fRepresentation == Representation::lightArrow) sceneHandler.EndPrimitives();
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}
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