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//
// Implementation of inline methods of G4TwistTrapParallelSide.
// --------------------------------------------------------------------

inline 
G4double G4TwistTrapParallelSide::GetValueB(G4double phi) 
{
  return ( fDy2plus1 + fDy2minus1 * ( 2 * phi ) / fPhiTwist ) ;
}

inline
G4double G4TwistTrapParallelSide::Xcoef(G4double phi)
{
  return GetValueB(phi)/2. ;
}

inline G4ThreeVector
G4TwistTrapParallelSide::
SurfacePoint( G4double phi, G4double u, G4bool isGlobal ) 
{
  // function to calculate a point on the surface, given by parameters phi,u

  G4ThreeVector SurfPoint ( u*std::cos(phi) - Xcoef(phi)*std::sin(phi)
                          + fdeltaX*phi/fPhiTwist,
                            u*std::sin(phi) + Xcoef(phi)*std::cos(phi)
                          + fdeltaY*phi/fPhiTwist,
                            2*fDz*phi/fPhiTwist  );
  if (isGlobal) { return (fRot * SurfPoint + fTrans); }
  return SurfPoint;
}


inline
G4double G4TwistTrapParallelSide::GetBoundaryMin(G4double phi)
{
  return  -(fPhiTwist*(fDx2 + fDx4 - fDy2plus1*fTAlph)
          + 2*fDx4minus2*phi - 2*fDy2minus1*fTAlph*phi)/(2.*fPhiTwist) ;
}

inline
G4double G4TwistTrapParallelSide::GetBoundaryMax(G4double phi)
{
  return (fDx2 + fDx4 + fDy2plus1*fTAlph)/ 2.
       + ((fDx4minus2 + fDy2minus1*fTAlph)*phi)/fPhiTwist ;
}

inline
G4double  G4TwistTrapParallelSide::GetSurfaceArea()
{
  return 2*fDx4plus2*fDz ;
}

inline
G4ThreeVector G4TwistTrapParallelSide::NormAng( G4double phi, G4double u ) 
{
  // function to calculate the norm at a given point on the surface
  // replace a1-d1

  G4ThreeVector nvec(-2*fDz*std::sin(phi) ,
                      2*fDz*std::cos(phi) ,
                     -(fDy2minus1 + fPhiTwist*u + fdeltaY*std::cos(phi)
                     -fdeltaX*std::sin(phi))) ;
  return nvec.unit();
}