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HxNgbIsMaxGradDir2d.h

/*
 *  Copyright (c) 1999, University of Amsterdam, The Netherlands.
 *  All rights reserved.
 *
 *  Author(s):
 *  Edo Poll                (poll@wins.uva.nl)
 */

#ifndef HxNgbIsMaxGradDir2d_h
#define HxNgbIsMaxGradDir2d_h

#include "HxClassName.h"
#include "HxSizes.h"
#include "HxCategories.h"
#include "HxCnum.h"
#include "HxTagList.h"


template<class ResultT, class ArithT>
class HxNgbIsMaxGradDir2d
{
public:

    typedef HxTagCnum           IteratorCategory;

    typedef HxTag1Phase         PhaseCategory;

    typedef HxCnum          CnumType;


                            HxNgbIsMaxGradDir2d(HxTagList& tags);

                            ~HxNgbIsMaxGradDir2d();

    HxSizes                 size();

    CnumType                begin();

    CnumType                end();

    void                    init(int x, int y, const ArithT& value);

    void                    next(int x, int y, const ArithT& value);

    ResultT                 result() const;

    static HxString         className();

private:
    HxCoord*                _coords;
    double                  _resultMag, _level;
    static HxCoord          _coordPairs[12];
    int                     _endIdx;
};

template<class ResultT, class ArithT>
inline HxNgbIsMaxGradDir2d<ResultT, ArithT>::CnumType
HxNgbIsMaxGradDir2d<ResultT, ArithT>::begin()
{
    return CnumType(&_coords[0]);
}

template<class ResultT, class ArithT>
inline HxNgbIsMaxGradDir2d<ResultT, ArithT>::CnumType
HxNgbIsMaxGradDir2d<ResultT, ArithT>::end()
{
    return CnumType(&_coords[_endIdx]);
}

template<class ResultT, class ArithT>
inline void
HxNgbIsMaxGradDir2d<ResultT, ArithT>::init(int, int, const ArithT& v)
{
    static const double tan22_5 = 0.41421356;
    static const double tan67_5 = 2.41421356;

    double x(v.x()), y(v.y());
    _resultMag = x*x+y*y;

    if (_resultMag < _level)
    {
        _endIdx = 0;
        return;
    }

    if (x == 0)
    {
        _endIdx = 2;
        _coords = &_coordPairs[4];
        return;
    }

    double rc = y/x;
    double frc = fabs(rc);
    int i = (frc < tan22_5) ? 0 : ( (frc < tan67_5) ? 1 : 2 );
    if (rc < 0)
        i += 3;
    _endIdx = 2;
    _coords = &_coordPairs[i<<1];
}

template<class ResultT, class ArithT>
inline HxString
HxNgbIsMaxGradDir2d<ResultT, ArithT>::className()
{
    static HxString s("isMaxGradDir");
    return s;
}

template<class ResultT, class ArithT>
inline void
HxNgbIsMaxGradDir2d<ResultT, ArithT>::next(int, int, const ArithT& v)
{
    if ((v.x()*v.x() + v.y()*v.y()) > _resultMag)
        _resultMag = 0;
}

template<class ResultT, class ArithT>
inline HxSizes  
HxNgbIsMaxGradDir2d<ResultT, ArithT>::size()
{
    return HxSizes(3, 3, 1);
}

template<class ResultT, class ArithT>
inline ResultT
HxNgbIsMaxGradDir2d<ResultT, ArithT>::result() const
{
    return _resultMag >= _level ? 1 : 0;
}

#ifdef INC_TEMPLATE_SRC
#include "HxNgbIsMaxGradDir2d.c"
#endif

#endif

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