/********************************************************************** * * GEOS - Geometry Engine Open Source * http://geos.osgeo.org * * 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: geomgraph/Quadrant.java rev. 1.8 (JTS-1.10) * **********************************************************************/ #ifndef GEOS_GEOMGRAPH_QUADRANT_H #define GEOS_GEOMGRAPH_QUADRANT_H #include #include #include // Forward declarations namespace geos { namespace geom { class Coordinate; } } namespace geos { namespace geomgraph { // geos.geomgraph /** * Utility functions for working with quadrants, which are numbered as follows: *
 * 1 | 0
 * --+--
 * 2 | 3
 * 
* */ class GEOS_DLL Quadrant { public: static const int NE = 0; static const int NW = 1; static const int SW = 2; static const int SE = 3; /** * Returns the quadrant of a directed line segment * (specified as x and y displacements, which cannot both be 0). * * @throws IllegalArgumentException if the displacements are both 0 */ static int quadrant(double dx, double dy); /** * Returns the quadrant of a directed line segment from p0 to p1. * * @throws IllegalArgumentException if the points are equal */ static int quadrant(const geom::Coordinate& p0, const geom::Coordinate& p1); /** * Returns true if the quadrants are 1 and 3, or 2 and 4 */ static bool isOpposite(int quad1, int quad2); /* * Returns the right-hand quadrant of the halfplane defined by * the two quadrants, * or -1 if the quadrants are opposite, or the quadrant if they * are identical. */ static int commonHalfPlane(int quad1, int quad2); /** * Returns whether the given quadrant lies within the given halfplane * (specified by its right-hand quadrant). */ static bool isInHalfPlane(int quad, int halfPlane); /** * Returns true if the given quadrant is 0 or 1. */ static bool isNorthern(int quad); }; } // namespace geos.geomgraph } // namespace geos #ifdef GEOS_INLINE # include "geos/geomgraph/Quadrant.inl" #endif #endif // ifndef GEOS_GEOMGRAPH_QUADRANT_H