/********************************************************************** * * GEOS - Geometry Engine Open Source * http://geos.osgeo.org * * Copyright (C) 2011 Sandro Santilli * 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 #include // 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 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 [Coordinates](@ref geom::Coordinate). * * @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