polylinend.h

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#pragma once

/*+
________________________________________________________________________

 (C) dGB Beheer B.V.; (LICENSE) http://opendtect.org/OpendTect_license.txt
 Author:        J.C. Glas
 Date:          Dec 2006
________________________________________________________________________

-*/

#include "math.h"
#include "typeset.h"


template <class T>
mClass(Algo) PolyLineND : public TypeSet<T>
{
public:
                PolyLineND(bool closed=false)
                    : closed_( closed )                                 {}

                PolyLineND(const TypeSet<T>& coords,bool closed=false)
                    : TypeSet<T>( coords )
                    , closed_( closed )                                 {}
                    
    void        setClosed(bool yn)                      { closed_ = yn; }
    bool        isClosed() const                        { return closed_; }

    double      distTo(const T& pt,int* segmentidxptr=0,
                       double* fractionptr=0) const;

    T           closestPoint(const T& pt) const;

    double      arcLength(int idx,double frac=0.0) const;
    double      arcLength(const T& pt) const;
    double      arcLength() const;

    T           getPoint(int idx,double frac=0.0) const;
    T           getPoint(double arclen) const;

protected:

    int         nextIdx(int) const;
    bool        closed_;
};


template <class T> inline
int PolyLineND<T>::nextIdx( int idx ) const
{
    if ( idx<0 || idx>=this->size() || !(*this)[idx].isDefined() )
        return mUdf(int);

    int idy = idx + 1;
    if ( idy>=this->size() || !(*this)[idy].isDefined() )
    {
        while ( (--idy)>=0 && (*this)[idy].isDefined() ) ;

        idy++;

        if ( !closed_ && idy!=idx )
            return mUdf(int);
    }

    return idy;
}


#define mUpdateMinDist( dist, idx, frac ) \
    if ( dist<mindist ) \
    { \
        mindist = dist; \
        if ( segmentidxptr ) \
            *segmentidxptr = idx; \
        if ( fractionptr ) \
            *fractionptr = frac; \
    }

template <class T> inline
double PolyLineND<T>::distTo( const T& pt, int* segmentidxptr,
                              double* fractionptr ) const
{
    double mindist = MAXDOUBLE;

    for ( int idx=0; idx<this->size(); idx++ )
    {
        const int idy = nextIdx( idx );
        if ( mIsUdf(idy) )
             continue;

        const double a2 = pt.sqDistTo( (*this)[idx] );
        const double b2 = pt.sqDistTo( (*this)[idy] );
        const double c2 = (*this)[idx].sqDistTo( (*this)[idy] );

        if ( c2<=0.0 || b2>=a2+c2 )
        {
            const double a = Math::Sqrt( a2 );
            mUpdateMinDist( a, idx, 0.0 );
        }
        else if ( a2 >= b2+c2 )
        {
            const double b = Math::Sqrt( b2 );
            mUpdateMinDist( b, idx, 1.0 );
        }
        else
        {
            const double c = Math::Sqrt( c2 );
            const double d = (a2+c2-b2) / (2*c);
            const double h = (a2-d*d)>0 ? Math::Sqrt(a2-d*d) : 0.0;
            mUpdateMinDist( h, idx, d/c );
        }
    }

    return mindist==MAXDOUBLE ? mUdf(double) : mindist;
}


template <class T> inline
T PolyLineND<T>::closestPoint( const T& pt ) const
{
    int idx = 0;
    double frac = 0;
    if ( mIsUdf( distTo(pt,&idx,&frac) ) )
        return T::udf();

    const int idy = nextIdx( idx );
    if ( mIsUdf(idy) )
        return T::udf();

    return (*this)[idx]*(1.0-frac) + (*this)[idy]*frac;
}


template <class T> inline
double PolyLineND<T>::arcLength( int index, double frac ) const
{
    if ( index<0 || index>=this->size() || frac<0.0 || frac>1.0 )
        return mUdf(double);

    double arclen = 0.0;

    for ( int idx=0; idx<=index; idx++ )
    {
        const int idy = nextIdx( idx );
        if ( mIsUdf(idy) )
             continue;

        const double len = (*this)[idx].template distTo<double>( (*this)[idy] );
        if ( idx==index )
            return arclen + len * frac;

        arclen += len;
    }

    return arclen;
}


template <class T> inline
double PolyLineND<T>::arcLength( const T& pt ) const
{
    int idx = 0;
    double frac = 0;
    if ( mIsUdf( distTo(pt,&idx,&frac) ) )
        return mUdf(double);

    return arcLength( idx, frac );
}


template <class T> inline
double PolyLineND<T>::arcLength() const
{
    return arcLength( this->size()-1, 1.0 );
}


template <class T> inline
T PolyLineND<T>::getPoint( int idx, double frac ) const
{
    if ( idx<0 || idx>=this->size() || frac<0.0 || frac>1.0 )
        return T::udf();

    if ( frac == 0.0 )
        return (*this)[idx];

    if ( frac==1.0 && !(*this)[idx].isDefined() )
        return getPoint( idx+1, 0.0 );

    const int idy = nextIdx( idx );
    if ( mIsUdf(idy) )
        return T::udf();

    return (*this)[idx]*(1.0-frac) + (*this)[idy]*frac;
}


template <class T> inline
T PolyLineND<T>::getPoint( double arclen ) const
{
    if ( arclen<0.0 )
        return T::udf();

    for ( int idx=0; idx<this->size(); idx++ )
    {
        const int idy = nextIdx( idx );
        if ( mIsUdf(idy) )
             continue;

        const double len = (*this)[idx].template distTo<double>( (*this)[idy] );
        if ( arclen <= len )
        {
            const double frac = arclen / len;
            return (*this)[idx]*(1.0-frac) + (*this)[idy]*frac;
        }

        arclen -= len;
    }

    return T::udf();
}