/**********************************************************************
 * $Id: HCoordinate.h 3338 2011-05-10 09:50:44Z strk $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * Copyright (C) 2011      Sandro Santilli <strk@keybit.net>
 * Copyright (C) 2005-2006 Refractions Research Inc.
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation. 
 * See the COPYING file for more information.
 *
 **********************************************************************
 *
 * Last port: algorithm/HCoordinate.java r386 (JTS-1.12+)
 *
 **********************************************************************/

#ifndef GEOS_ALGORITHM_HCOORDINATE_H
#define GEOS_ALGORITHM_HCOORDINATE_H

#include <geos/export.h>
#include <iosfwd>

// Forward declarations
namespace geos {
	namespace geom {
		class Coordinate;
	}
}

namespace geos {
namespace algorithm { // geos::algorithm


/** \brief
 * Represents a homogeneous coordinate in a 2-D coordinate space.
 *
 * HCoordinate are used as a clean way
 * of computing intersections between line segments.
 */
class GEOS_DLL HCoordinate {

public:

	friend std::ostream& operator<< (std::ostream& o, const HCoordinate& c);

	/** \brief
	 * Computes the (approximate) intersection point between two line
	 * segments using homogeneous coordinates.
	 * 
	 * Note that this algorithm is
	 * not numerically stable; i.e. it can produce intersection points which
	 * lie outside the envelope of the line segments themselves.  In order
	 * to increase the precision of the calculation input points should be
	 * normalized before passing them to this routine.
	 */
	static void intersection(const geom::Coordinate &p1,
				 const geom::Coordinate &p2,
				 const geom::Coordinate &q1,
				 const geom::Coordinate &q2,
				 geom::Coordinate &ret);

	double x,y,w;

	HCoordinate();

	HCoordinate(double _x, double _y, double _w);

	HCoordinate(const geom::Coordinate& p);

	/** \brief
	 * Constructs a homogeneous coordinate which is the intersection
	 * of the lines define by the homogenous coordinates represented
	 * by two {@link Coordinate}s.
	 *
	 * @param p1
	 * @param p2
	 */
	HCoordinate(const geom::Coordinate& p1, const geom::Coordinate& p2);

	HCoordinate(const geom::Coordinate& p1, const geom::Coordinate& p2,
		    const geom::Coordinate& q1, const geom::Coordinate& q2);

	HCoordinate(const HCoordinate &p1, const HCoordinate &p2);

	double getX() const;

	double getY() const;

	void getCoordinate(geom::Coordinate &ret) const;

};

std::ostream& operator<< (std::ostream& o, const HCoordinate& c);

} // namespace geos::algorithm
} // namespace geos

#endif // GEOS_ALGORITHM_HCOORDINATE_H

