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// 
// --------------------------------------------------------------------
// GEANT 4 class header file
//
//
// G4FlatTrapSurface
//
// Class description:
//
//  Class describing a flat boundary surface for a trapezoid.

// Author:
//
//   27-Oct-2004 - O.Link (Oliver.Link@cern.ch)
//
// --------------------------------------------------------------------
#ifndef __G4TWISTTRAPFLATSIDE__
#define __G4TWISTTRAPFLATSIDE__

#include "G4VTwistSurface.hh"

class G4TwistTrapFlatSide : public G4VTwistSurface
{
  public:  // with description

   G4TwistTrapFlatSide( const G4String& name,
                              G4double  PhiTwist,
                              G4double  pDx1,
                              G4double  pDx2,
                              G4double  pDy,
                              G4double  pDz,
                              G4double  pAlpha,
                              G4double  pPhi,
                              G4double  pTheta,
                              G4int     handedness  );
   virtual ~G4TwistTrapFlatSide();

   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[]);


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

  public:  // without description

   G4TwistTrapFlatSide(__void__&);
     // Fake default constructor for usage restricted to direct object
     // persistency for clients requiring preallocation of memory for
     // persistifiable objects.

  protected:  // with description

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

  private:

   virtual void SetCorners();
   virtual void SetBoundaries();

   inline double xAxisMax(G4double u, G4double fTanAlpha) const;
 
  private:
  
   G4double fDx1;
   G4double fDx2;
   G4double fDy;
   G4double fDz;
   G4double fPhiTwist;
   G4double fAlpha;
   G4double fTAlph;
   G4double fPhi;
   G4double fTheta;
   G4double fdeltaX;
   G4double fdeltaY;
};

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

inline 
G4double G4TwistTrapFlatSide::xAxisMax(G4double u, G4double fTanAlpha) const
{
  return (  ( fDx2 + fDx1 )/2. + u*(fDx2 - fDx1)/(2.*fDy) + u *fTanAlpha  ) ;
}

inline G4ThreeVector
G4TwistTrapFlatSide::SurfacePoint(G4double x, G4double y, G4bool isGlobal)
{
  G4ThreeVector SurfPoint ( x,y,0);

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

inline
G4double G4TwistTrapFlatSide::GetBoundaryMin(G4double y )
{
  return -xAxisMax(y, -fTAlph ) ;
}

inline
G4double G4TwistTrapFlatSide::GetBoundaryMax(G4double y )
{
  return xAxisMax(y, fTAlph ) ; 
}

inline
G4double G4TwistTrapFlatSide::GetSurfaceArea()
{
  return 2*(fDx1 + fDx2)*fDy ;
}

#endif
