#ifndef Polygon2_HH
#define Polygon2_HH
//////////////////////////////////////////////////////////////////////////
//! file="amma/Geometry/CmpGeo2d/Polygon2.hh"
//! lib=Mcg2
//! userlevel=Normal
//! author="Radek Marik"
//! docentry="Geometry.2-D"
//! date="20.08.1994"
//! rcsid="$Id: Polygon2.hh,v 1.5 1999/05/24 10:33:02 ees1cg Exp $"

#include "amma/DList.hh"
#include "amma/Line2dPP.hh"
#include "amma/LiPoint2.hh"

class GfSetC;
class SubPolygon2dC;
class istream;
class ostream;

//====================================================================
//======= Polygon2dC ================================================
//====================================================================

//: A polygon in 2d space
// The Polygon2dC class is a representation of a polygon in 2 dimensional
// space. A polygon is the region of a plane bounded by a finite collection
// of line segments forming a simple closed curve. <p>
// Ref.: -  O'Rourke,J.: Computatinal geometry in C;
//          Cambridge University Press, 1994, p. 1 <p>
// BIG OBJECT

class Polygon2dC: private Point2dListC
{
public:
  inline Polygon2dC();
  // Empty polygon.
  
  inline Polygon2dC(const Point2dListC & points);
  // Constructs a polygon from a list of points. The 'points' will
  // be shared by the polygon (as a big object).
  
  Polygon2dC(const Polygon2dC & points);
  // Another access to the polygon.
  
  Polygon2dC(const SubPolygon2dC & pol);
  // Creates the polygon from the subset of vertexes of another polygon.
  
  Polygon2dC(const char * s);
  // Creates the polygon from one item of a GF set.

  inline const DListC<Point2dC> & List() const;
  // Access to the constant list of vertexes.
  
  RealT Area2() const;
  // Returns twice the signed area of this polygon.
  // Ref.: -  O'Rourke,J.: Computatinal geometry in C;
  //          Cambridge University Press, 1994, pp. 20-26
  
  BooleanT 
  IsDiagonalie(const Point2dCLIterC & a, const Point2dCLIterC & b) const;
  // Returns TRUE if (a, b) is a proper internal *or* external 
  // diagonal of this polygon. The edges incident to 'a' and 'b'
  // are ignored.
  // Ref.: -  O'Rourke,J.: Computatinal geometry in C;
  //          Cambridge University Press, 1994, pp. 35-36
  
  BooleanT
  IsInCone(const Point2dCLIterC & a, const Point2dCLIterC & b) const;
  // Returns TRUE iff the diagonal (a,b) is strictly internal
  // to this polygon in the neighborhood of the 'a' endpoint.
  // Ref.: -  O'Rourke,J.: Computatinal geometry in C;
  //          Cambridge University Press, 1994, pp. 37-38
  
  inline
  BooleanT
  IsDiagonal(const Point2dCLIterC & a, const Point2dCLIterC & b) const;
  // Returns TRUE iff (a,b) is a proper internal diagonal of 
  // this polygon.
  // Ref.: -  O'Rourke,J.: Computatinal geometry in C;
  //          Cambridge University Press, 1994, pp. 38-39
  
  BooleanT Contains(const Point2dC & p) const;
  // Returns TRUE iff the point 'p' is an internal point of this polygon.
  
  DListC<Line2dPPC> Triangulate();
  // Returns the set of diagonals of this polygon. The polygon vertexes are
  // supposed to be in the counter-clockwise order and they can
  // be collinear. The polygon is destroyed. 
  // Ref.: -  O'Rourke,J.: Computatinal geometry in C;
  //          Cambridge University Press, 1994, pp. 35-42
  
  void SaveAsGF(ostream & s);
  // Saves the polygon into the output stream 's' in GF format.
  
  //private:
  
  inline Point2dListC & List();
  //: Access to the list of vertexes.
  // This was private, I'm not clear why...
  
  friend istream & operator>>(istream & s, Polygon2dC & pol);
  friend ostream & operator<<(ostream & s, const Polygon2dC & pol);
};

istream & 
operator>>(istream & s, Polygon2dC & pol);
// Reads a polygon from the input stream.

ostream & 
operator<<(ostream & s, const Polygon2dC & pol);
// Sends the polygon into the output stream.

DListC<Polygon2dC> Polygons2d(const GfSetC & s);
// Creates the list of polygons in 2D space from the GF set 's'.

//====================================================================
//======= Polygon2dC ================================================
//====================================================================

inline 
const DListC<Point2dC> & 
Polygon2dC::List() const
//======================
{ return *this; }

inline 
Point2dListC & 
Polygon2dC::List()
//================
{ return *this; }

inline 
Polygon2dC::Polygon2dC()
//======================
: Point2dListC()
{}

inline 
Polygon2dC::Polygon2dC(const Point2dListC & points)
//=================================================
: Point2dListC(points)
{}

inline
BooleanT
Polygon2dC::IsDiagonal(const Point2dCLIterC & a, 
                       const Point2dCLIterC & b) const
//====================================================
{ return IsInCone(a,b) && IsDiagonalie(a,b); }

#endif

// IAPS - Image analysis program system.
// End of include file Polygon2.hh