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// $Id: G4PolyPhiFace.icc,v 1.6 2006/06/29 18:47:10 gunter Exp $
// GEANT4 tag $Name: geant4-09-03 $
//
// 
// --------------------------------------------------------------------
// GEANT 4 inline definitions file
//
// G4PolyPhiFace.icc
//
// Implementation of inline methods of G4PolyPhiFace
// --------------------------------------------------------------------

inline
G4VCSGface* G4PolyPhiFace::Clone()
{
  return new G4PolyPhiFace(*this);
}

// ExactZOrder
//
// Decide precisely whether a trajectory passes to the left, right, or exactly 
// passes through the z position of a vertex point in our face.
//
// Result is only determined within an arbitrary (positive) factor.
//      > 0 to the right
//      < 0 to the left
//      = 0 exactly on top of
// In 99.9999% of the cases, a trivial calculation is used. In difficult
// cases, a precise, compliant calculation is relied on.
//
inline
G4double G4PolyPhiFace::ExactZOrder( G4double z, 
                                     G4double qx, G4double qy, G4double qz, 
                               const G4ThreeVector &v, 
                                     G4double normSign,
                               const G4PolyPhiFaceVertex *vert ) const
{
  G4double answer = vert->z - z;
  if (std::fabs(answer) < kCarTolerance)
  {
    G4ThreeVector qa( qx - vert->x + radial.x(),
                      qy - vert->y + radial.y(), qz - vert->z ),
                      qb( qx - vert->x, qy - vert->y, qz - vert->z );
    G4ThreeVector qacb = qa.cross(qb); 

    answer = normSign*qacb.dot(v)*(normal.y()*radial.x()-normal.x()*radial.y());
  }
  
  return answer;
}