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// G4TwistBoxSide
//
// Class description:
//
// G4TwistBoxSide describes a twisted boundary surface for a trapezoid.

// Author: 27-Oct-2004 - O.Link (Oliver.Link@cern.ch)
// --------------------------------------------------------------------
#ifndef G4TWISTBOXSIDE_HH
#define G4TWISTBOXSIDE_HH

#include "G4VTwistSurface.hh"

#include <vector>

class G4TwistBoxSide : public G4VTwistSurface
{
  public:  // with description
   
    G4TwistBoxSide(const G4String& name,
                         G4double  PhiTwist, // twist angle
                         G4double  pDz,      // half z lenght
                         G4double  pTheta,   // direction between end planes
                         G4double  pPhi,     // by polar and azimutal angles
                         G4double  pDy1,     // half y length at -pDz
                         G4double  pDx1,     // half x length at -pDz,-pDy
                         G4double  pDx2,     // half x length at -pDz,+pDy
                         G4double  pDy2,     // half y length at +pDz
                         G4double  pDx3,     // half x length at +pDz,-pDy
                         G4double  pDx4,     // half x length at +pDz,+pDy
                         G4double  pAlph,    // tilt angle at +pDz
                         G4double  AngleSide // parity
                   );
  
    virtual ~G4TwistBoxSide();
   
    virtual G4ThreeVector  GetNormal(const G4ThreeVector& xx,
                                           G4bool isGlobal = false) ;   
   
    virtual G4int DistanceToSurface(const G4ThreeVector& gp,
                                    const G4ThreeVector& gv,
                                          G4ThreeVector  gxx[],
                                          G4double  distance[],
                                          G4int     areacode[],
                                          G4bool    isvalid[],
                                    EValidate validate = kValidateWithTol);
                                                  
    virtual G4int DistanceToSurface(const G4ThreeVector& gp,
                                          G4ThreeVector  gxx[],
                                          G4double       distance[],
                                          G4int          areacode[]);

  public:  // without description

    G4TwistBoxSide(__void__&);
      // Fake default constructor for usage restricted to direct object
      // persistency for clients requiring preallocation of memory for
      // persistifiable objects.

  private:

    virtual G4int GetAreaCode(const G4ThreeVector& xx, 
                                    G4bool         withTol = true);
    virtual void SetCorners();
    virtual void SetBoundaries();

    void GetPhiUAtX(G4ThreeVector p, G4double& phi, G4double& u);
    G4ThreeVector ProjectPoint(const G4ThreeVector& p,
                                     G4bool isglobal = false);

    virtual G4ThreeVector SurfacePoint(G4double phi, G4double u,
                                       G4bool isGlobal = false);
    virtual G4double GetBoundaryMin(G4double phi);
    virtual G4double GetBoundaryMax(G4double phi);
    virtual G4double GetSurfaceArea();
    virtual void GetFacets( G4int m, G4int n, G4double xyz[][3],
                            G4int faces[][4], G4int iside );

    inline G4double GetValueA(G4double phi);
    inline G4double GetValueB(G4double phi);
    inline G4ThreeVector NormAng(G4double phi, G4double u);
    inline G4double Xcoef(G4double u, G4double phi);
      // To calculate the w(u) function

  private:

    G4double fTheta;   
    G4double fPhi ;

    G4double fDy1;   
    G4double fDx1;     
    G4double fDx2;     

    G4double fDy2;   
    G4double fDx3;     
    G4double fDx4;     

    G4double fDz;         // Half-length along the z axis

    G4double fAlph;
    G4double fTAlph;      // std::tan(fAlph)
    
    G4double fPhiTwist;   // twist angle ( dphi in surface equation)

    G4double fAngleSide;

    G4double fdeltaX;
    G4double fdeltaY;

    G4double fDx4plus2;   // fDx4 + fDx2  == a2/2 + a1/2
    G4double fDx4minus2;  // fDx4 - fDx2          -
    G4double fDx3plus1;   // fDx3 + fDx1  == d2/2 + d1/2
    G4double fDx3minus1;  // fDx3 - fDx1          -
    G4double fDy2plus1;   // fDy2 + fDy1  == b2/2 + b1/2
    G4double fDy2minus1;  // fDy2 - fDy1          -
    G4double fa1md1;      // 2 fDx2 - 2 fDx1  == a1 - d1
    G4double fa2md2;      // 2 fDx4 - 2 fDx3
};   

//========================================================
// inline functions
//========================================================

inline
G4double G4TwistBoxSide::GetValueA(G4double phi)
{
  return ( fDx4plus2 + fDx4minus2 * ( 2 * phi ) / fPhiTwist  ) ;
}


inline 
G4double G4TwistBoxSide::GetValueB(G4double phi) 
{
  return ( fDy2plus1 + fDy2minus1 * ( 2 * phi ) / fPhiTwist ) ;
}

inline
G4double G4TwistBoxSide::Xcoef(G4double u, G4double phi)
{
  
  return GetValueA(phi)/2. + u*fTAlph    ;

}

inline G4ThreeVector
G4TwistBoxSide::SurfacePoint( G4double phi, G4double u, G4bool isGlobal ) 
{
  // function to calculate a point on the surface, given by parameters phi,u

  G4ThreeVector SurfPoint ( Xcoef(u,phi) * std::cos(phi)
                          - u * std::sin(phi) + fdeltaX*phi/fPhiTwist,
                            Xcoef(u,phi) * std::sin(phi)
                          + u * std::cos(phi) + fdeltaY*phi/fPhiTwist,
                            2*fDz*phi/fPhiTwist  );

  if (isGlobal) { return (fRot * SurfPoint + fTrans); }
  return SurfPoint;
}

inline
G4double G4TwistBoxSide::GetBoundaryMin(G4double phi)
{
  return -0.5*GetValueB(phi) ;
}

inline
G4double G4TwistBoxSide::GetBoundaryMax(G4double phi)
{
  return 0.5*GetValueB(phi) ;
}

inline
G4double G4TwistBoxSide::GetSurfaceArea()
{
  return (fDz*(std::sqrt(16*fDy1*fDy1
         + (fa1md1 + 4*fDy1*fTAlph)*(fa1md1 + 4*fDy1*fTAlph))
         + std::sqrt(16*fDy1*fDy1 + (fa2md2 + 4*fDy1*fTAlph)
         * (fa2md2 + 4*fDy1*fTAlph))))/2. ;
}

inline
G4ThreeVector G4TwistBoxSide::NormAng( G4double phi, G4double u ) 
{
  // function to calculate the norm at a given point on the surface
  // replace a1-d1

  G4ThreeVector nvec( 4*fDz*(std::cos(phi) + fTAlph*std::sin(phi)) ,
                      4*fDz*(-(fTAlph*std::cos(phi)) + std::sin(phi)),
                      (fDx2 + fDx4)*fPhiTwist*fTAlph
                                   + 2*fDx4minus2*(-1 + fTAlph*phi)
                                   + 2*fPhiTwist*(1 + fTAlph*fTAlph)*u
                                - 2*(fdeltaX - fdeltaY*fTAlph)*std::cos(phi)
                                - 2*(fdeltaY + fdeltaX*fTAlph)*std::sin(phi) );
  return nvec.unit();
}

#endif
