Import Geant4 10.4.0.beta source tree

source/visualization/modeling/History

@@ -1,4 +1,4 @@
-$Id: History 101035 2016-11-04 08:48:17Z gcosmo $
+$Id: History 104164 2017-05-15 06:53:09Z gcosmo $
 -------------------------------------------------------------------
 
      =========================================================
@@ -20,6 +20,28 @@ committal in the CVS repository !
 History file for visualization/modeling
 ---------------------------------------
 
+14th May 2017  John Allison (modeling-V10-03-07)
+- G4GPSModel: Added user-selectable colour.
+
+3rd May 2017  John Allison (modeling-V10-03-06)
+- Needs event-V10-03-01.
+- Completed G4GPSModel for visualisation of General Particle Source. Can
+  be used with command /vis/scene/add/gps.
+
+3rd May 2017  John Allison (modeling-V10-03-05)
+- Added prototype/skeleton G4GPSModel.
+- G4PhysicalVolumeModel::Validate:
+  o Check world pointer (can be null if geometry has been cleared/destroyed).
+
+19th April 2017  John Allison (modeling-V10-03-01)
+- Added G4ModelingParameters::PVPointerCopyNo.
+
+9th December 2016  John Allison (modeling-V10-03-00)
+- Coworks with visman-V10-03-00.
+- G4MagneticFieldModel: Augmented to take lineSegmentsPerCircle.
+  Default is 6 for rapid yet adequate drawing, but this my be changed
+  with /vis/set/arrow3DLineSegmentsPerCircle.
+
 3rd November 2016  John Allison (modeling-V10-02-17)
 - G4ModelingParameters and G4PhysicalVolumeModel:
   Changed default number of line segments per circle from 24 to 72.

source/visualization/modeling/include/G4GPSModel.hh

@@ -0,0 +1,77 @@
+//
+// ********************************************************************
+// * License and Disclaimer                                           *
+// *                                                                  *
+// * The  Geant4 software  is  copyright of the Copyright Holders  of *
+// * the Geant4 Collaboration.  It is provided  under  the terms  and *
+// * conditions of the Geant4 Software License,  included in the file *
+// * LICENSE and available at  http://cern.ch/geant4/license .  These *
+// * include a list of copyright holders.                             *
+// *                                                                  *
+// * Neither the authors of this software system, nor their employing *
+// * institutes,nor the agencies providing financial support for this *
+// * work  make  any representation or  warranty, express or implied, *
+// * regarding  this  software system or assume any liability for its *
+// * use.  Please see the license in the file  LICENSE  and URL above *
+// * for the full disclaimer and the limitation of liability.         *
+// *                                                                  *
+// * This  code  implementation is the result of  the  scientific and *
+// * technical work of the GEANT4 collaboration.                      *
+// * By using,  copying,  modifying or  distributing the software (or *
+// * any work based  on the software)  you  agree  to acknowledge its *
+// * use  in  resulting  scientific  publications,  and indicate your *
+// * acceptance of all terms of the Geant4 Software license.          *
+// ********************************************************************
+//
+//
+// $Id: G4GPSModel.hh 99642 2016-09-29 19:49:30Z allison $
+//
+// 
+// John Allison  26th April 2017.
+//
+// Class Description:
+//
+// Model for a representation of the General Paricle Source.
+
+#ifndef G4GPSMODEL_HH
+#define G4GPSMODEL_HH
+
+#include "G4VModel.hh"
+
+#include "G4String.hh"
+#include "G4Colour.hh"
+
+class G4VGraphicsScene;
+
+class G4GPSModel: public G4VModel {
+
+public: // With description
+
+  G4GPSModel (const G4Colour& colour = G4Colour(1.,0.,0.,0.3));
+  // Create with colour (default red and transparent).
+
+  virtual ~G4GPSModel ();
+
+  void DescribeYourselfTo (G4VGraphicsScene&);
+  // The main task of a model is to describe itself to the graphics scene
+  // handler (a object which inherits G4VSceneHandler, which inherits
+  // G4VGraphicsScene).
+
+  G4String GetCurrentDescription () const;
+  // A description which depends on the current state of the model.
+
+  G4String GetCurrentTag () const;
+  // A tag which depends on the current state of the model.
+
+protected:
+
+  G4Colour fColour;
+
+private:
+  // Private copy constructor and assigment operator - copying and
+  // assignment not allowed.  Keeps CodeWizard happy.
+  G4GPSModel (const G4GPSModel&);
+  G4GPSModel& operator = (const G4GPSModel&);
+};
+
+#endif

source/visualization/modeling/include/G4MagneticFieldModel.hh

@@ -24,7 +24,7 @@
 // ********************************************************************
 //
 //
-// $Id: G4MagneticFieldModel.hh 93069 2015-10-02 09:54:27Z gcosmo $
+// $Id: G4MagneticFieldModel.hh 101958 2016-12-12 08:04:35Z gcosmo $
 //
 // 
 // John Allison  17th August 2013
@@ -49,7 +49,8 @@ public: // With description
 
   G4MagneticFieldModel
   (G4int nDataPointsPerHalfScene = 10,
-   Representation representation = Representation::fullArrow);
+   Representation representation = Representation::fullArrow,
+   G4int arrow3DLineSegmentsPerCircle = 6);
   virtual ~G4MagneticFieldModel ();
 
   virtual void DescribeYourselfTo (G4VGraphicsScene&);
@@ -68,6 +69,7 @@ private:
 
   Representation fRepresentation;
 
+  G4int fArrow3DLineSegmentsPerCircle;
 };
 
 #endif

source/visualization/modeling/include/G4ModelingParameters.hh

@@ -24,7 +24,7 @@
 // ********************************************************************
 //
 //
-// $Id: G4ModelingParameters.hh 99418 2016-09-21 09:18:42Z gcosmo $
+// $Id: G4ModelingParameters.hh 103627 2017-04-19 13:30:26Z gcosmo $
 //
 // 
 // John Allison  31st December 1997.
@@ -39,6 +39,7 @@
 #include "globals.hh"
 #include "G4VisExtent.hh"
 #include "G4VisAttributes.hh"
+#include "G4VPhysicalVolume.hh"
 #include "G4PhysicalVolumeModel.hh"
 
 #include <vector>
@@ -77,8 +78,14 @@ public: // With description
 
   class PVNameCopyNo {
   public:
-    PVNameCopyNo(G4String name, G4int copyNo):
-    fName(name), fCopyNo(copyNo) {}
+    // Normal constructor
+    PVNameCopyNo(G4String name, G4int copyNo)
+    : fName(name), fCopyNo(copyNo) {}
+    // Constructor from G4PhysicalVolumeModel::G4PhysicalVolumeNodeID
+    PVNameCopyNo
+    (const G4PhysicalVolumeModel::G4PhysicalVolumeNodeID& nodeID)
+    : fName(nodeID.GetPhysicalVolume()->GetName())
+    , fCopyNo(nodeID.GetCopyNo()) {}
     const G4String& GetName() const {return fName;}
     G4int GetCopyNo() const {return fCopyNo;}
     G4bool operator!=(const PVNameCopyNo&) const;
@@ -87,10 +94,31 @@ public: // With description
     G4String fName;
     G4int fCopyNo;
   };
-
   typedef std::vector<PVNameCopyNo> PVNameCopyNoPath;
   typedef PVNameCopyNoPath::const_iterator PVNameCopyNoPathConstIterator;
 
+  class PVPointerCopyNo {
+  public:
+    // Normal constructor
+    PVPointerCopyNo(G4VPhysicalVolume* pPV, G4int copyNo)
+    : fpPV(pPV), fCopyNo(copyNo) {}
+    // Constructor from G4PhysicalVolumeModel::G4PhysicalVolumeNodeID
+    PVPointerCopyNo
+    (const G4PhysicalVolumeModel::G4PhysicalVolumeNodeID& nodeID)
+    : fpPV(nodeID.GetPhysicalVolume())
+    , fCopyNo(nodeID.GetCopyNo()) {}
+    const G4String& GetName() const;
+    const G4VPhysicalVolume* GetPVPointer() const {return fpPV;}
+    G4int GetCopyNo() const {return fCopyNo;}
+    G4bool operator!=(const PVPointerCopyNo&) const;
+    G4bool operator==(const PVPointerCopyNo& rhs) const {return !operator!=(rhs);}
+  private:
+    G4VPhysicalVolume* fpPV;
+    G4int fCopyNo;
+  };
+  typedef std::vector<PVPointerCopyNo> PVPointerCopyNoPath;
+  typedef PVPointerCopyNoPath::const_iterator PVPointerCopyNoPathConstIterator;
+
   class VisAttributesModifier {
   public:
     VisAttributesModifier
@@ -182,6 +210,9 @@ public: // With description
   friend std::ostream& operator <<
   (std::ostream& os, const PVNameCopyNoPath&);
 
+  friend std::ostream& operator <<
+  (std::ostream& os, const PVPointerCopyNoPath&);
+
   friend std::ostream& operator <<
   (std::ostream& os,
    const std::vector<VisAttributesModifier>&);
@@ -212,6 +243,9 @@ std::ostream& operator <<
 std::ostream& operator <<
 (std::ostream& os, const G4ModelingParameters::PVNameCopyNoPath&);
 
+std::ostream& operator <<
+(std::ostream& os, const G4ModelingParameters::PVPointerCopyNoPath&);
+
 std::ostream& operator <<
 (std::ostream& os,
  const std::vector<G4ModelingParameters::VisAttributesModifier>&);

source/visualization/modeling/sources.cmake

@@ -11,7 +11,7 @@
 #
 # Generated on : 24/9/2010
 #
-# $Id: sources.cmake 99176 2016-09-07 09:46:36Z gcosmo $
+# $Id: sources.cmake 103926 2017-05-03 13:43:27Z gcosmo $
 #
 #------------------------------------------------------------------------------
 
@@ -60,6 +60,7 @@ GEANT4_DEFINE_MODULE(NAME G4modeling
         G4CallbackModel.hh
         G4DigiFilterFactories.hh
         G4DigiModel.hh
+        G4GPSModel.hh
         G4HitFilterFactories.hh
         G4HitsModel.hh
         G4LogicalVolumeModel.hh
@@ -109,6 +110,7 @@ GEANT4_DEFINE_MODULE(NAME G4modeling
         G4BoundingSphereScene.cc
         G4DigiFilterFactories.cc
         G4DigiModel.cc
+        G4GPSModel.cc
         G4HitFilterFactories.cc
         G4HitsModel.cc
         G4LogicalVolumeModel.cc

source/visualization/modeling/src/G4GPSModel.cc

@@ -0,0 +1,186 @@
+//
+// ********************************************************************
+// * License and Disclaimer                                           *
+// *                                                                  *
+// * The  Geant4 software  is  copyright of the Copyright Holders  of *
+// * the Geant4 Collaboration.  It is provided  under  the terms  and *
+// * conditions of the Geant4 Software License,  included in the file *
+// * LICENSE and available at  http://cern.ch/geant4/license .  These *
+// * include a list of copyright holders.                             *
+// *                                                                  *
+// * Neither the authors of this software system, nor their employing *
+// * institutes,nor the agencies providing financial support for this *
+// * work  make  any representation or  warranty, express or implied, *
+// * regarding  this  software system or assume any liability for its *
+// * use.  Please see the license in the file  LICENSE  and URL above *
+// * for the full disclaimer and the limitation of liability.         *
+// *                                                                  *
+// * This  code  implementation is the result of  the  scientific and *
+// * technical work of the GEANT4 collaboration.                      *
+// * By using,  copying,  modifying or  distributing the software (or *
+// * any work based  on the software)  you  agree  to acknowledge its *
+// * use  in  resulting  scientific  publications,  and indicate your *
+// * acceptance of all terms of the Geant4 Software license.          *
+// ********************************************************************
+//
+//
+// $Id: G4GPSModel.cc 100959 2016-11-03 14:13:37Z allison $
+//
+//
+// John Allison  26th April 2017.
+// Model for a representation of the General Paricle Source.
+
+#include "G4GPSModel.hh"
+
+#include "G4VGraphicsScene.hh"
+#include "G4GeneralParticleSourceData.hh"
+#include "G4VisAttributes.hh"
+#include "G4GeometryTolerance.hh"
+#include "G4PhysicalConstants.hh"
+#include "G4Transform3D.hh"
+#include "G4Point3D.hh"
+#include "G4Circle.hh"
+#include "G4Tubs.hh"
+#include "G4Box.hh"
+#include "G4EllipticalTube.hh"
+#include "G4Orb.hh"
+#include "G4Ellipsoid.hh"
+#include "G4Para.hh"
+
+#include <sstream>
+
+G4GPSModel::G4GPSModel (const G4Colour& colour)
+: fColour(colour)
+{
+  fType = "G4GPSModel";
+  std::ostringstream oss;
+  oss << "G4GPSModel for General Particle Source " << fColour;
+  fGlobalTag = oss.str();
+  fGlobalDescription = fGlobalTag;
+}
+
+G4GPSModel::~G4GPSModel () {}
+
+G4String G4GPSModel::GetCurrentTag () const
+{
+return "";
+}
+
+G4String G4GPSModel::GetCurrentDescription () const
+{
+  return "G4GPSModel " + GetCurrentTag ();
+}
+
+void G4GPSModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
+// The main task of a model is to describe itself to the graphics scene
+// handler (a object which inherits G4VSceneHandler, which inherits
+// G4VGraphicsScene).
+{
+  G4GeneralParticleSourceData* pGPSData = G4GeneralParticleSourceData::Instance();
+  // Note: As far as I can see, if this is the first time Instance has been
+  // called, it will, nevertheless, instantiate a default source, Type:"Point",
+  // Shaep: "NULL", which will be drawn as a small circle at the origin of
+  // coordinates whether you have set up GPS or not.  Sorry, can't think of a
+  // way to avoid that.  Mostly, of course, you will only invoke this function,
+  // if you have - or are about to - set up GPS, in which case all will be well.
+  if (!pGPSData) return;
+
+  G4int nSources = pGPSData->GetSourceVectorSize();
+  for (G4int iSource = 0; iSource < nSources; ++iSource) {
+
+    const G4SingleParticleSource* pCurrentSingleSource = pGPSData->GetCurrentSource(iSource);
+    if (!pCurrentSingleSource) return;
+
+    const G4SPSPosDistribution* pSPSPosDistribution = pCurrentSingleSource->GetPosDist();
+    if (!pSPSPosDistribution) return;
+
+    G4String Type = pSPSPosDistribution->GetPosDisType();
+    G4String Shape = pSPSPosDistribution->GetPosDisShape();
+    // Type can be: Point, Plane, Surface or Volume
+    // Shape can be: Square, Circle, Ellipse, Rectangle,
+    //    Sphere, Ellipsoid, Cylinder, Parallelepiped
+//    G4cout
+//    << "G4GPSModel::DescribeYourselfTo"
+//    << ": PosDisType: " << Type
+//    << ", Shape: " << Shape
+//    << G4endl;
+
+    const G4double& halfx = pSPSPosDistribution->GetHalfX();
+    const G4double& halfy = pSPSPosDistribution->GetHalfY();
+    const G4double& halfz = pSPSPosDistribution->GetHalfZ();
+    const G4double& Radius  = pSPSPosDistribution->GetRadius();
+    const G4double& Radius0 = pSPSPosDistribution->GetRadius0();
+    const G4double& ParAlpha = pSPSPosDistribution->GetParAlpha();
+    const G4double& ParTheta = pSPSPosDistribution->GetParTheta();
+    const G4double& ParPhi   = pSPSPosDistribution->GetParPhi();
+
+    const G4ThreeVector& Rotx = pSPSPosDistribution->GetRotx();
+    const G4ThreeVector& Roty = pSPSPosDistribution->GetRoty();
+    const G4ThreeVector& Rotz = pSPSPosDistribution->GetRotz();
+
+    const G4ThreeVector& position = pSPSPosDistribution->GetCentreCoords();
+    G4Transform3D transform(CLHEP::HepXHat,CLHEP::HepYHat,CLHEP::HepZHat,Rotx,Roty,Rotz);
+    transform = G4Translate3D(position) * transform;
+
+    G4double surfaceTolerance = G4GeometryTolerance::GetInstance()->GetSurfaceTolerance();
+    G4double smallHalfThickness = 10.*surfaceTolerance;
+
+    G4VisAttributes gpsAtts;
+    gpsAtts.SetColour(fColour);
+    gpsAtts.SetForceSolid();
+    
+    if (Type == "Point") {
+
+      G4Circle circle;
+      circle.SetPosition(position);
+      circle.SetScreenDiameter(10.);
+      circle.SetVisAttributes(gpsAtts);
+      sceneHandler.BeginPrimitives(transform);
+      sceneHandler.AddPrimitive(circle);
+      sceneHandler.EndPrimitives();
+
+    } else if (Type == "Plane") {
+
+      // Code based on G4SPSPosDistribution::GeneratePointsInPlane.
+      sceneHandler.PreAddSolid(transform,gpsAtts);
+      if (Shape == "Circle") {
+        sceneHandler.AddSolid
+        (G4Tubs("GPS_Circle",0.,Radius,smallHalfThickness,0.,twopi));
+      } else if (Shape == "Annulus") {
+        sceneHandler.AddSolid
+        (G4Tubs("GPS_Annulus",Radius0,Radius,smallHalfThickness,0.,twopi));
+      } else if (Shape == "Ellipse") {
+        sceneHandler.AddSolid
+        (G4EllipticalTube("GPS_Ellipse",halfx,halfy,smallHalfThickness));
+      } else if (Shape == "Square") {
+        sceneHandler.AddSolid
+        (G4Box("GPS_Ellipse",halfx,halfx,smallHalfThickness));
+      } else if (Shape == "Rectangle") {
+        sceneHandler.AddSolid
+        (G4Box("GPS_Rectangle",halfx,halfy,smallHalfThickness));
+      }
+      sceneHandler.PostAddSolid();
+
+    } else if (Type == "Surface" || Type == "Volume") {
+      
+      // Code based on G4SPSPosDistribution::GeneratePointsOnSurface.
+      // and           G4SPSPosDistribution::GeneratePointsInVolume.
+      sceneHandler.PreAddSolid(transform,gpsAtts);
+      if (Shape == "Sphere") {
+        sceneHandler.AddSolid
+        (G4Orb("GPS_Sphere",Radius));
+      } else if (Shape == "Ellipsoid") {
+        sceneHandler.AddSolid
+        (G4Ellipsoid("GPS_Ellipsoid",halfx,halfy,halfz));
+      } else if (Shape == "Cylinder") {
+        sceneHandler.AddSolid
+        (G4Tubs("GPS_Cylinder",0.,Radius, halfz, 0., twopi));
+      } else if (Shape == "Para") {
+        sceneHandler.AddSolid
+        (G4Para("GPS_Para",halfx,halfy,halfz,ParAlpha,ParTheta,ParPhi));
+      }
+      sceneHandler.PostAddSolid();
+
+    }
+  }
+}

source/visualization/modeling/src/G4MagneticFieldModel.cc

@@ -24,7 +24,7 @@
 // ********************************************************************
 //
 //
-// $Id: G4MagneticFieldModel.cc 94206 2015-11-09 08:11:59Z gcosmo $
+// $Id: G4MagneticFieldModel.cc 101958 2016-12-12 08:04:35Z gcosmo $
 //
 // 
 // John Allison  17th August 2013
@@ -51,15 +51,18 @@ G4MagneticFieldModel::~G4MagneticFieldModel () {}
 
 G4MagneticFieldModel::G4MagneticFieldModel
 (G4int nDataPointsPerMaxHalfScene,
- Representation representation)
+ Representation representation,
+ G4int arrow3DLineSegmentsPerCircle)
 : fNDataPointsPerMaxHalfScene(nDataPointsPerMaxHalfScene)
 , fRepresentation(representation)
+, fArrow3DLineSegmentsPerCircle(arrow3DLineSegmentsPerCircle)
 {
   fType = "G4MagneticFieldModel";
   fGlobalTag = fType;
   std::ostringstream oss;
-  oss << fNDataPointsPerMaxHalfScene;
-  fGlobalDescription = fType + ':' + oss.str();
+  oss << ':' << fNDataPointsPerMaxHalfScene
+  << ':' << fArrow3DLineSegmentsPerCircle;
+  fGlobalDescription = fType + oss.str();
 }
 
 void G4MagneticFieldModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
@@ -109,14 +112,6 @@ void G4MagneticFieldModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
           warned = true;
         }
       }
-    } else {
-      static G4bool warned = false;
-      if (!warned) {
-        G4cout  << intro
-        << "No global field exists."
-        << G4endl;
-        warned = true;
-      }
     }
   } else {
     static G4bool warned = false;
@@ -270,7 +265,9 @@ void G4MagneticFieldModel::DescribeYourselfTo (G4VGraphicsScene& sceneHandler)
         const G4double y2 = y1 + arrowLength * By / B;
         const G4double z2 = z1 + arrowLength * Bz / B;
         if (fRepresentation == Representation::fullArrow) {
-          G4ArrowModel BArrow(x1,y1,z1,x2,y2,z2,arrowLength/5,arrowColour);
+          G4ArrowModel BArrow(x1,y1,z1,x2,y2,z2,arrowLength/5,arrowColour,
+                              "BField",
+                              fArrow3DLineSegmentsPerCircle);
           BArrow.DescribeYourselfTo(sceneHandler);
         } else if (fRepresentation == Representation::lightArrow) {
           G4Polyline BArrowLite;

source/visualization/modeling/src/G4ModelingParameters.cc

@@ -24,7 +24,7 @@
 // ********************************************************************
 //
 //
-// $Id: G4ModelingParameters.cc 101035 2016-11-04 08:48:17Z gcosmo $
+// $Id: G4ModelingParameters.cc 103627 2017-04-19 13:30:26Z gcosmo $
 //
 // 
 // John Allison  31st December 1997.
@@ -249,14 +249,6 @@ G4bool G4ModelingParameters::operator !=
   return false;
 }
 
-G4bool G4ModelingParameters::PVNameCopyNo::operator!=
-(const G4ModelingParameters::PVNameCopyNo& rhs) const
-{
-  if (fName != rhs.fName) return true;
-  if (fCopyNo != rhs.fCopyNo) return true;
-  return false;
-}
-
 G4bool G4ModelingParameters::VisAttributesModifier::operator!=
 (const G4ModelingParameters::VisAttributesModifier& rhs) const
 {
@@ -310,6 +302,14 @@ G4bool G4ModelingParameters::VisAttributesModifier::operator!=
   return false;
 }
 
+G4bool G4ModelingParameters::PVNameCopyNo::operator!=
+(const G4ModelingParameters::PVNameCopyNo& rhs) const
+{
+  if (fName != rhs.fName) return true;
+  if (fCopyNo != rhs.fCopyNo) return true;
+  return false;
+}
+
 std::ostream& operator <<
 (std::ostream& os, const G4ModelingParameters::PVNameCopyNoPath& path)
 {
@@ -324,6 +324,33 @@ std::ostream& operator <<
   return os;
 }
 
+const G4String& G4ModelingParameters::PVPointerCopyNo::GetName() const
+{
+  return fpPV->GetName();
+}
+
+G4bool G4ModelingParameters::PVPointerCopyNo::operator!=
+(const G4ModelingParameters::PVPointerCopyNo& rhs) const
+{
+  if (fpPV != rhs.fpPV) return true;
+  if (fCopyNo != rhs.fCopyNo) return true;
+  return false;
+}
+
+std::ostream& operator <<
+(std::ostream& os, const G4ModelingParameters::PVPointerCopyNoPath& path)
+{
+  os << "Touchable path: physical-volume-pointer:copy-number pairs:\n  ";
+  G4ModelingParameters::PVPointerCopyNoPathConstIterator i;
+  for (i = path.begin(); i != path.end(); ++i) {
+    if (i != path.begin()) {
+      os << ',';
+    }
+    os << '(' << (void*)(i->GetPVPointer()) << ')' << i->GetName() << ':' << i->GetCopyNo();
+  }
+  return os;
+}
+
 std::ostream& operator <<
 (std::ostream& os,
  const std::vector<G4ModelingParameters::VisAttributesModifier>& vams)

source/visualization/modeling/src/G4PhysicalVolumeModel.cc

@@ -24,7 +24,7 @@
 // ********************************************************************
 //
 //
-// $Id: G4PhysicalVolumeModel.cc 101035 2016-11-04 08:48:17Z gcosmo $
+// $Id: G4PhysicalVolumeModel.cc 103926 2017-05-03 13:43:27Z gcosmo $
 //
 // 
 // John Allison  31st December 1997.
@@ -720,6 +720,7 @@ G4bool G4PhysicalVolumeModel::Validate (G4bool warn)
     transportationManager->GetWorldsIterator();
   for (size_t i = 0; i < nWorlds; ++i, ++iterWorld) {
     G4VPhysicalVolume* world = (*iterWorld);
+    if (!world) break; // This can happen if geometry has been cleared/destroyed.
     // The idea now is to seek a PV with the same name and copy no
     // in the hope it's the same one!!
     G4PhysicalVolumeModel searchModel (world);