text: // Created on: 2013-12-20
  // Created by: Denis BOGOLEPOV
  // Copyright (c) 2013-2014 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_Triangulation_Header
  #define _BVH_Triangulation_Header
  
  #include <BVH_PrimitiveSet.hxx>
  
  //! Triangulation as an example of BVH primitive set.
  //! \tparam T Numeric data type
  //! \tparam N Vector dimension
  template<class T, int N>
  class BVH_Triangulation : public BVH_PrimitiveSet<T, N>
  {
  public:
  
    typedef typename BVH::VectorType<T, N>::Type BVH_VecNt;
  
  public:
  
    //! Creates empty triangulation.
    BVH_Triangulation() {}
  
    //! Creates empty triangulation.
    BVH_Triangulation (const opencascade::handle<BVH_Builder<T, N> >& theBuilder)
    : BVH_PrimitiveSet<T, N> (theBuilder)
    {
      //
    }
  
    //! Releases resources of triangulation.
    virtual ~BVH_Triangulation() {}
  
  public:
  
    //! Array of vertex coordinates.
    typename BVH::ArrayType<T, N>::Type Vertices;
  
    //! Array of indices of triangle vertices.
    BVH_Array4i Elements;
  
  public:
  
    //! Returns total number of triangles.
    virtual Standard_Integer Size() const Standard_OVERRIDE
    {
      return BVH::Array<Standard_Integer, 4>::Size (Elements);
    }
  
    //! Returns AABB of entire set of objects.
    using BVH_PrimitiveSet<T, N>::Box;
  
    //! Returns AABB of the given triangle.
    virtual BVH_Box<T, N> Box (const Standard_Integer theIndex) const Standard_OVERRIDE
    {
      const BVH_Vec4i& anIndex = BVH::Array<Standard_Integer, 4>::Value (Elements, theIndex);
  
      const BVH_VecNt& aPoint0 = BVH::Array<T, N>::Value (Vertices, anIndex.x());
      const BVH_VecNt& aPoint1 = BVH::Array<T, N>::Value (Vertices, anIndex.y());
      const BVH_VecNt& aPoint2 = BVH::Array<T, N>::Value (Vertices, anIndex.z());
  
      BVH_VecNt aMinPoint (aPoint0), aMaxPoint (aPoint0);
  
      BVH::BoxMinMax<T, N>::CwiseMin (aMinPoint, aPoint1);
      BVH::BoxMinMax<T, N>::CwiseMin (aMinPoint, aPoint2);
      BVH::BoxMinMax<T, N>::CwiseMax (aMaxPoint, aPoint1);
      BVH::BoxMinMax<T, N>::CwiseMax (aMaxPoint, aPoint2);
      return BVH_Box<T, N> (aMinPoint, aMaxPoint);
    }
  
    //! Returns centroid position along the given axis.
    virtual T Center (const Standard_Integer theIndex,
                      const Standard_Integer theAxis) const Standard_OVERRIDE
    {
      const BVH_Vec4i& anIndex = BVH::Array<Standard_Integer, 4>::Value (Elements, theIndex);
  
      const BVH_VecNt& aPoint0 = BVH::Array<T, N>::Value (Vertices, anIndex.x());
      const BVH_VecNt& aPoint1 = BVH::Array<T, N>::Value (Vertices, anIndex.y());
      const BVH_VecNt& aPoint2 = BVH::Array<T, N>::Value (Vertices, anIndex.z());
      return (BVH::VecComp<T, N>::Get (aPoint0, theAxis) +
              BVH::VecComp<T, N>::Get (aPoint1, theAxis) +
              BVH::VecComp<T, N>::Get (aPoint2, theAxis)) * static_cast<T> (1.0 / 3.0);
    }
  
    //! Performs transposing the two given triangles in the set.
    virtual void Swap (const Standard_Integer theIndex1,
                       const Standard_Integer theIndex2) Standard_OVERRIDE
    {
      BVH_Vec4i& anIndices1 = BVH::Array<Standard_Integer, 4>::ChangeValue (Elements, theIndex1);
      BVH_Vec4i& anIndices2 = BVH::Array<Standard_Integer, 4>::ChangeValue (Elements, theIndex2);
      std::swap (anIndices1, anIndices2);
    }
  
  };
  
  #endif // _BVH_Triangulation_Header
  