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// $Id$
//
/////////////////////////////////////////////////////////////////////////////////
//      Class Name:	G4AdjointPosOnPhysVolGenerator
//	Author:       	L. Desorgher
// 	Organisation: 	SpaceIT GmbH
//	Contract:	ESA contract 21435/08/NL/AT
// 	Customer:     	ESA/ESTEC
/////////////////////////////////////////////////////////////////////////////////
//
// CHANGE HISTORY
// --------------
//      ChangeHistory: 
//	 	1st June 2006 creation by L. Desorgher  		
//
//-------------------------------------------------------------
//	Documentation:
//		This class is responsible for the generation of primary adjoint particle on the external surface of a user selected volume.
//		The particle are generated uniformly on the surface with the angular distribution  set to a cosine law relative to normal of the surface.
//		It is equivalent to  the flux going in  from the surface if an  isotropic flux is considered outside. 
//		It uses ray tracking technique and can be applied to all kind of convex volume. Uisng the ray tracking technique the area 
//		of the external surface is also computed. The area is needed to fix the weight of the primary adjoint particle.  
//		At the time of the development of this class, generation of particle on volume surface and computation of surface was limited in G4, 
//		therfore the general ray tracking technique was adopted. It could be now (2009) that direct method of G4VSolid could be used instead. To be checked! 
//
//		
//
#ifndef G4AdjointPosOnPhysVolGenerator_h
#define G4AdjointPosOnPhysVolGenerator_h 1

#include "G4VPhysicalVolume.hh"
#include "G4AffineTransform.hh"
#include "G4ThreeVector.hh"

class G4VSolid;

class G4AdjointPosOnPhysVolGenerator 
///////////////////////
{

//--------
  public: //without description
//--------

   static  G4AdjointPosOnPhysVolGenerator* GetInstance();
   
//--------
  public:  //public methods
//--------
  G4VPhysicalVolume* DefinePhysicalVolume(const G4String& aName);
  void DefinePhysicalVolume1(const G4String& aName);
  G4double ComputeAreaOfExtSurface();
  G4double ComputeAreaOfExtSurface(G4int NStat);
  G4double ComputeAreaOfExtSurface(G4double epsilon);
  G4double ComputeAreaOfExtSurface(G4VSolid* aSolid);
  G4double ComputeAreaOfExtSurface(G4VSolid* aSolid,G4int NStat);
  G4double ComputeAreaOfExtSurface(G4VSolid* aSolid,G4double epsilon);
 
  void GenerateAPositionOnTheExtSurfaceOfASolid(G4VSolid* aSolid,G4ThreeVector& p, G4ThreeVector&  direction);
  void GenerateAPositionOnTheExtSurfaceOfTheSolid(G4ThreeVector& p, G4ThreeVector&  direction);
  void GenerateAPositionOnTheExtSurfaceOfThePhysicalVolume(G4ThreeVector& p, G4ThreeVector&  direction);
  void GenerateAPositionOnTheExtSurfaceOfThePhysicalVolume(G4ThreeVector& p, G4ThreeVector&  direction,
  										G4double& costh_to_normal);

  //inline public methods
   
  inline void SetSolid(G4VSolid* aSolid){theSolid=aSolid;}
  inline G4double GetAreaOfExtSurfaceOfThePhysicalVolume(){return AreaOfExtSurfaceOfThePhysicalVolume;}
  inline G4double GetCosThDirComparedToNormal(){return CosThDirComparedToNormal;}
  
//---------   
   private:   //private methods
//---------  
   G4AdjointPosOnPhysVolGenerator();
  ~G4AdjointPosOnPhysVolGenerator();
   G4double ComputeAreaOfExtSurfaceStartingFromSphere(G4VSolid* aSolid,G4int NStat);
   G4double ComputeAreaOfExtSurfaceStartingFromBox(G4VSolid* aSolid,G4int NStat);
   void GenerateAPositionOnASolidBoundary(G4VSolid* aSolid,G4ThreeVector& p, G4ThreeVector&  direction);
   G4double GenerateAPositionOnASphereBoundary(G4VSolid* aSolid,G4ThreeVector& p, G4ThreeVector&  direction);
   G4double GenerateAPositionOnABoxBoundary(G4VSolid* aSolid,G4ThreeVector& p, G4ThreeVector&  direction);
   void ComputeTransformationFromPhysVolToWorld();

//---------   
   private: //attributes
//---------   
   static G4AdjointPosOnPhysVolGenerator* theInstance;
   G4VSolid* theSolid;
   G4VPhysicalVolume* thePhysicalVolume;
   G4bool UseSphere;
   G4String ModelOfSurfaceSource;
   G4AffineTransform theTransformationFromPhysVolToWorld;
   G4double AreaOfExtSurfaceOfThePhysicalVolume;
   G4double CosThDirComparedToNormal;
};

#endif