// Created by: Olga Suryaninova
// Created on: 2019-11-25
// Copyright (c) 2019 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _BVH_Ray_Header
#define _BVH_Ray_Header

#include "BVH_Types.hxx"

#include <limits>

//! Describes a ray based on BVH vectors.
template <class T, int N>
class BVH_Ray
{
public:
  typedef typename BVH::VectorType<T, N>::Type BVH_VecNt;

public:
  BVH_VecNt Origin;    //!< Ray origin point
  BVH_VecNt Direct;    //!< Ray direction vector
  BVH_VecNt InvDirect; //!< Reciprocal of direction (1/Direct)

public:
  //! Creates ray with given origin and direction.
  constexpr BVH_Ray(const BVH_VecNt& theOrigin, const BVH_VecNt& theDirect) noexcept
      : Origin(theOrigin),
        Direct(theDirect),
        InvDirect(computeInvDirect(theDirect))
  {
  }

  //! Default constructor (creates invalid ray at origin).
  constexpr BVH_Ray() noexcept
      : Origin(BVH_VecNt()),
        Direct(BVH_VecNt()),
        InvDirect(BVH_VecNt())
  {
  }

private:
  //! Computes reciprocal of direction component (returns infinity for zero).
  static constexpr T invComponent(T theDir) noexcept
  {
    return (theDir != T(0)) ? (T(1) / theDir) : std::numeric_limits<T>::infinity();
  }

  //! Computes reciprocal of direction vector.
  static constexpr BVH_VecNt computeInvDirect(const BVH_VecNt& theDirect) noexcept
  {
    static_assert(N >= 1 && N <= 4, "BVH_Ray only supports dimensions 1 to 4");
    if constexpr (N == 1)
    {
      return BVH_VecNt(invComponent(theDirect[0]));
    }
    else if constexpr (N == 2)
    {
      return BVH_VecNt(invComponent(theDirect.x()), invComponent(theDirect.y()));
    }
    else if constexpr (N == 3)
    {
      return BVH_VecNt(invComponent(theDirect.x()),
                       invComponent(theDirect.y()),
                       invComponent(theDirect.z()));
    }
    else // N == 4
    {
      return BVH_VecNt(invComponent(theDirect.x()),
                       invComponent(theDirect.y()),
                       invComponent(theDirect.z()),
                       invComponent(theDirect.w()));
    }
  }
};

#endif // _BVH_Ray_Header