PointSphereNearest.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 __solve_PointSphereNearest_h__
#define __solve_PointSphereNearest_h__

namespace fe
{
namespace ext
{

/**************************************************************************//**
    @brief Find nearest point on sphere

    @ingroup solve
*//***************************************************************************/
template <typename T>
class PointSphereNearest
{
    public:
static  T       solve(const Vector<3,T>& center,const T radius,
                        const Vector<3,T>& origin,
                        Vector<3,T>& direction);

static  BWORD   within(const Vector<3,T>& center,const T radius,
                        const Vector<3,T>& origin,const T distance);
};

template <typename T>
inline T PointSphereNearest<T>::solve(const Vector<3,T>& center,T radius,
        const Vector<3,T>& origin,Vector<3,T>& direction)
{
    const Vector<3,T> to_origin=origin-center;
    const T mag=magnitude(to_origin);
    if(mag>T(0))
    {
        direction= -T(1)/mag*to_origin;
    }
    else
    {
        set(direction);
    }
    return mag-radius;
}

template <typename T>
inline BWORD PointSphereNearest<T>::within(const Vector<3,T>& center,T radius,
        const Vector<3,T>& origin,const T distance)
{
    const Vector<3,T> to_origin=origin-center;
    const T mag2=magnitudeSquared(to_origin);
    const T sum=distance+radius;

    return (mag2<=(sum*sum));
}

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

#endif /* __solve_PointSphereNearest_h__ */