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// $Id: G4Para.hh,v 1.18 2006/10/19 15:33:37 gcosmo Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
//
// --------------------------------------------------------------------
// GEANT 4 class header file
//
// G4Para
//
// Class description:
//
//   A G4Parallepiped, essentially a box with half lengths dx,dy,dz
//   `skewed' so that there are angles theta & phi of the polar line
//   joining the faces at +-dz in z, and alpha formed by the y axis
//   and the plane joinng the centre of the faces G4Parallel to the
//   z-x plane at -dy and +dy.
//
//   A G4Para is defined by:
//   dx,dy,dz - Half-length in x,y,z
//   alpha    - Angle formed by the y axis and by the plane joining
//              the centre of the faces G4Parallel to the z-x plane
//              at -dy and +dy
//   theta    - Polar angle of the line joining the centres of the
//              faces at -dz and +dz in z
//   phi      - Azimuthal angle of the line joining the centres of the
//              faces at -dz and +dz in z
//   Member data:
//
//   Note that the angles parameters are not stored - precomputed trig is
//   stored instead.
//
//      fDx   Half-length in x
//      fDy   Half-length in y
//      fDz   Half-length in z
//
//      fTalpha       Tan of alpha
//      fTthetaCphi   Tan theta * Cos phi
//      fTthetaSphi   Tan theta * Sin phi

// History:
// 21.3.94 P.Kent Old C++ code converted to tolerant geometry
// 31.10.96 V.Grichine Modifications according G4Box/Tubs before to commit
// 18.11.99 V.Grichine , kUndefined was added to ESide
// --------------------------------------------------------------------

#ifndef G4Para_HH
#define G4Para_HH

#include "G4CSGSolid.hh"

class G4Para : public G4CSGSolid
{
  public:  // with description

    G4Para(const G4String& pName,
                 G4double pDx, G4double pDy, G4double pDz,
                 G4double pAlpha, G4double pTheta, G4double pPhi);
     
    G4Para(const G4String& pName,
           const G4ThreeVector pt[8]);

    virtual ~G4Para();
    
  // Accessors

    inline G4double GetZHalfLength()  const;
    inline G4ThreeVector GetSymAxis() const;
    inline G4double GetYHalfLength()  const;
    inline G4double GetXHalfLength()  const;
    inline G4double GetTanAlpha()     const;
    
  // Modifiers

    inline void SetXHalfLength(G4double val);
    inline void SetYHalfLength(G4double val);
    inline void SetZHalfLength(G4double val);
    inline void SetAlpha(G4double alpha);
    inline void SetTanAlpha(G4double val);
    inline void SetThetaAndPhi(double pTheta, double pPhi);

    void SetAllParameters(G4double pDx, G4double pDy, G4double pDz, 
                          G4double pAlpha, G4double pTheta, G4double pPhi);
    
  // Other methods of solid
    
    inline G4double GetCubicVolume();
    inline G4double GetSurfaceArea();

    void ComputeDimensions(G4VPVParameterisation* p,
                           const G4int n,
                           const G4VPhysicalVolume* pRep);

    G4bool CalculateExtent(const EAxis pAxis,
                           const G4VoxelLimits& pVoxelLimit,
                           const G4AffineTransform& pTransform,
                                 G4double& pMin, G4double& pMax) const;    
        
    EInside Inside(const G4ThreeVector& p) const;

    G4ThreeVector SurfaceNormal( const G4ThreeVector& p) const;

    G4double DistanceToIn(const G4ThreeVector& p,
                          const G4ThreeVector& v) const;
    G4double DistanceToIn(const G4ThreeVector& p) const;
    
    G4double DistanceToOut(const G4ThreeVector& p, const G4ThreeVector& v,
                           const G4bool calcNorm=G4bool(false),
                                 G4bool *validNorm=0, G4ThreeVector *n=0) const;
    G4double DistanceToOut(const G4ThreeVector& p) const;

    G4GeometryType GetEntityType() const;

    G4ThreeVector GetPointOnSurface() const; 

    std::ostream& StreamInfo(std::ostream& os) const;

  // Visualisation functions

    void          DescribeYourselfTo (G4VGraphicsScene& scene) const;
    G4Polyhedron* CreatePolyhedron   () const;
    G4NURBS*      CreateNURBS        () const;

  public:  // without description

    G4Para(__void__&);
      // Fake default constructor for usage restricted to direct object
      // persistency for clients requiring preallocation of memory for
      // persistifiable objects.

  protected:  // without description

    G4ThreeVectorList*
    CreateRotatedVertices(const G4AffineTransform& pTransform) const;

  private:

    G4ThreeVector ApproxSurfaceNormal( const G4ThreeVector& p) const;
      // Algorithm for SurfaceNormal() following the original
      // specification for points not on the surface

    G4ThreeVector GetPointOnPlane(G4ThreeVector p0, G4ThreeVector p1, 
                                  G4ThreeVector p2, G4ThreeVector p3, 
                                  G4double& area) const;
      // Returns a random point on the surface of one of the faces.

 private:

    G4double fDx,fDy,fDz;
    G4double fTalpha,fTthetaCphi,fTthetaSphi;
};

#include "G4Para.icc"

#endif
