SegmentPointComparator.h

/**********************************************************************
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.osgeo.org
 *
 * Copyright (C) 2006      Refractions Research 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: noding/SegmentPointComparator.java r320 (JTS-1.12)
 *
 **********************************************************************/
 
#ifndef GEOS_NODING_SEGMENTPOINTCOMPARATOR_H
#define GEOS_NODING_SEGMENTPOINTCOMPARATOR_H
 
#include <geos/export.h>
#include <geos/geom/Coordinate.h>
#include <cassert>
 
namespace geos {
namespace noding { // geos.noding

class GEOS_DLL SegmentPointComparator {
 
public:

        static int compare(int octant, const geom::Coordinate& p0,
                        const geom::Coordinate& p1)
        {
                // nodes can only be equal if their coordinates are equal
                if (p0.equals2D(p1)) return 0;
 
                int xSign = relativeSign(p0.x, p1.x);
                int ySign = relativeSign(p0.y, p1.y);
 
                switch (octant) {
                        case 0: return compareValue(xSign, ySign);
                        case 1: return compareValue(ySign, xSign);
                        case 2: return compareValue(ySign, -xSign);
                        case 3: return compareValue(-xSign, ySign);
                        case 4: return compareValue(-xSign, -ySign);
                        case 5: return compareValue(-ySign, -xSign);
                        case 6: return compareValue(-ySign, xSign);
                        case 7: return compareValue(xSign, -ySign);
                }
                assert(0); // invalid octant value
                return 0;
         
        }
 
        static int relativeSign(double x0, double x1)
        {
                if (x0 < x1) return -1;
                if (x0 > x1) return 1;
                return 0;
        }
 
        static int compareValue(int compareSign0, int compareSign1)
        {
                if (compareSign0 < 0) return -1;
                if (compareSign0 > 0) return 1;
                if (compareSign1 < 0) return -1;
                if (compareSign1 > 0) return 1;
                return 0;
        }
 
};
 
} // namespace geos.noding
} // namespace geos
 
#endif // GEOS_NODING_SEGMENTPOINTCOMPARATOR_H