#ifndef __DRCSURFPOLYPARA_H__
#define __DRCSURFPOLYPARA_H__

/*! 
  \brief Representation of a parabolic surface

  It is limited by a polygon made up by points. The "radius" of the parabolic surface
  can be given. The radius is twice the focal length. The definition of the 
  parabola is given by \f$ p-z = \frac{x^2+y^2}{2p}\f$, where p plays 
  the role of the radius.
 
  The definition is very close to that of \sa DrcSurfPolySphere

  The borders of the parabola are 
  defined by a projection on the x-y plane. This projection is defined by a polygone
  with points which you can add. 

  \sa addPoint

  The z-components of these points have to be zero.
  Such defined, the paraboloid can be positioned and rotated by
  \sa shift \sa rotate
  The rotation is performed before the shift operation.

*/

class DrcSurfPolyPara : public DrcSurfPolyFlat
{
 private:
  //!                                             The radius of the sphere.
  double       m_radius;
  //!                                             Flag if dimensions are checked.
  mutable bool m_checked;
  //!                                             Transform
  Transform3D       m_trans;
  //!                                             Inverse transform
  Transform3D       m_transInv;

 private:
  /*! \brief Auxiliary function for assignment operator and copy constructor..
    \param s The object to copy.
  */
  void copy(const DrcSurfPolyPara& s);         

  /*! \brief Check dimensions of parabolic surface.

  The radius has to be given and the points of the polygon have to be such that
  the projection is within the half parabolic shape.
  /return true if ok.
  */
  bool check() const;

 public:

  DrcSurfPolyPara();                    //!< Empty constructor.

  /*! \brief Copy constructor.
    \param s Object to copy.
  */
  DrcSurfPolyPara(const DrcSurfPolyPara& s);

  /*! \brief Assignment operator.
    \param s Object to assign.
  */
  DrcSurfPolyPara& operator=(const DrcSurfPolyPara& s);

  virtual ~DrcSurfPolyPara(){};

  /*! \brief Set the radius of the sphere.

  \param radius The radius [mm]
  */
  void setRadius(double radius){m_radius=radius;};

  /*! Point limiting the sphere.

  The paraboloid construction points are not the same as the limiting points 
  of the sphere itself. This function returns the limiting points.
    \param i Index of point starting with 0
    \return The point.
  */
  XYZPoint limitingPoint(unsigned int i);

  /*! Center point of the surface.

  Like the /sa limitingPoint this function returns the point on the z-axis 
  at construction after applying transformations.
  \return The transformed center point.
  */
  XYZPoint centerPoint();

  // implemetation of pure virtual functions.
  virtual  DrcSurfPolyPara* clone() const;
  XYZVector normal(const XYZPoint& point)   const; 
  bool     surfaceHit(DrcPhoton& ph, 
		      XYZPoint&  pos_new, 
		      double&    path_length) const;
  void     print(fstream& stream)          const;
  void     addTransform(const Transform3D& trans);
  virtual bool isFlat(){return false;};
};
#endif