RayDiskIntersect.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_RayDiskIntersect_h__
#define __solve_RayDiskIntersect_h__

namespace fe
{
namespace ext
{

/**************************************************************************//**
    @brief Find intersection between ray and circular solid

    @ingroup solve
*//***************************************************************************/
template <typename T>
class RayDiskIntersect
{
    public:
static  T       solve(const Vector<3,T>& center,const Vector<3,T>& facing,
                        const T radius,
                        const Vector<3,T>& origin,
                        const Vector<3,T>& direction,
                        Vector<3,T>& intersection);
static  void    resolveContact(const Vector<3,T>& center,
                        const Vector<3,T>& facing,
                        const T radius,
                        const Vector<3,T>& origin,
                        const Vector<3,T>& direction,
                        const T range,
                        const Vector<3,T>& intersection,
                        Vector<3,T>& normal);
};

// direction must be normalized
template <typename T>
inline T RayDiskIntersect<T>::solve(const Vector<3,T>& center,
        const Vector<3,T>& facing,T radius,
        const Vector<3,T>& origin, const Vector<3,T>& direction,
        Vector<3,T>& intersection)
{
//  feLog("center %s facing %s radius %.6G\n",c_print(center),radius);
//  feLog("origin: %s\n",c_print(origin));
//  feLog("direction: %s\n",c_print(direction));

    const T incident=dot(facing,direction);
    if(incident==0.0f)
    {
        return T(-1);
    }
    const T range=(dot(facing,center)-dot(facing,origin))/incident;

    intersection=origin+direction*range;
//  feLog("intersection: %s sq %.6G vs %.6G\n",c_print(intersection),
//          magnitudeSquared(intersection-center),radius*radius);

    if(magnitudeSquared(intersection-center)>radius*radius)
    {
        return T(-1);
    }

    return range;
}

// direction must be normalized
template <typename T>
inline void RayDiskIntersect<T>::resolveContact(
        const Vector<3,T>& center,
        const Vector<3,T>& facing,
        const T radius,
        const Vector<3,T>& origin,
        const Vector<3,T>& direction,
        const T range,
        const Vector<3,T>& intersection,
        Vector<3,T>& normal)
{
    normal=facing;
}

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

#endif /* __solve_RayDiskIntersect_h__ */