PointCurveNearest.h

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/*  Copyright (C) 2003-2021 Free Electron Organization
    Any use of this software requires a license.  If a valid license
    was not distributed with this file, visit freeelectron.org. */

/** @file */

#ifndef __geometry_PointCurveNearest_h__
#define __geometry_PointCurveNearest_h__

namespace fe
{
namespace ext
{

/**************************************************************************//**
    @brief Find point nearest to a curve with radius

    @ingroup geometry
*//***************************************************************************/
template <typename T>
class PointCurveNearest
{
    public:
static  T   solve(const Vector<3,T>* a_pVertex,const U32 a_vertCount,
                    const T a_radius,
                    const Vector<3,T>& a_origin,Vector<3,T>& a_direction,
                    T& a_along,Vector<3,T>& a_intersection);
};

template <typename T>
inline T PointCurveNearest<T>::solve(
    const Vector<3,T>* a_pVertex,const U32 a_vertCount,
    const T a_radius,
    const Vector<3,T>& a_origin, Vector<3,T>& a_direction,
    T& a_along,Vector<3,T>& a_intersection)
{
#if FALSE
    feLog("PointCurveNearest< %s >::solve %s radius %.6G\n",
            FE_TYPESTRING(T).c_str(),
            c_print(a_origin),a_radius);
    for(U32 m=0;m<a_vertCount;m++)
    {
        feLog("  %d/%d %s\n",m,a_vertCount,c_print(a_pVertex[m]));
    }
#endif

    if(a_vertCount<2)
    {
        return T(-1);
    }

    T bestAlong=0.0;
    T bestMag= -1.0;
    I32 bestIndex=0;
    for(U32 m=0;m<a_vertCount-1;m++)
    {
        const Vector<3,T> segment=a_pVertex[m+1]-a_pVertex[m];
        Vector<3,T> oneIntersection;
        T oneAlong;
        T oneMag=PointCylinderNearest<T>::solve(a_pVertex[m],segment,
                a_radius,a_origin,a_direction,oneAlong,oneIntersection);
        if(oneMag>=0.0 && (bestMag<0.0 || oneMag<bestMag))
        {
            const T length=magnitude(segment);
            bestAlong=oneAlong*(length>0.0? 1.0/length: 1.0);
            a_intersection=oneIntersection;
            bestMag=oneMag;
            bestIndex=m;
        }

#if FALSE
        feLog("  %d/%d mag %.6G along %.6G at %s\n",m,a_vertCount,
                oneMag,oneAlong,c_print(oneIntersection));
#endif

    }

    FEASSERT(bestAlong>=0.0);
    FEASSERT(bestAlong<=1.0);

    a_along=(bestMag<0.0)? 0.0: (bestIndex+bestAlong)/(a_vertCount-1.0);

#if FALSE
        feLog("  bestMag %.6G along %.6G \n",bestMag,a_along);
#endif

    return bestMag;
}

} /* namespace ext */
} /* namespace fe */

#endif /* __geometry_PointCurveNearest_h__ */