0027368: Finding objects in vicinity of a ray

[occt.git] / src / BVH / BVH_QuickSorter.lxx

// Created on: 2016-04-13
// Created by: Denis BOGOLEPOV
// Copyright (c) 2013-2016 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.

// =======================================================================
// function : Perform
// purpose  :
// =======================================================================
template<class T, int N>
void BVH_QuickSorter<T, N>::Perform (BVH_Set<T, N>* theSet)
{
  Perform (theSet, 0, theSet->Size() - 1);
}

// =======================================================================
// function : Perform
// purpose  :
// =======================================================================
template<class T, int N>
void BVH_QuickSorter<T, N>::Perform (BVH_Set<T, N>* theSet, const Standard_Integer theStart, const Standard_Integer theFinal)
{
  Standard_Integer aLft = theStart;
  Standard_Integer aRgh = theFinal;

  T aPivot = theSet->Center ((aRgh + aLft) / 2, myAxis);

  while (aLft < aRgh)
  {
    while (theSet->Center (aLft, myAxis) < aPivot && aLft < theFinal)
    {
      ++aLft;
    }

    while (theSet->Center (aRgh, myAxis) > aPivot && aRgh > theStart)
    {
      --aRgh;
    }

    if (aLft <= aRgh)
    {
      if (aLft != aRgh)
      {
        theSet->Swap (aLft, aRgh);
      }

      ++aLft;
      --aRgh;
    }
  }

  if (aRgh > theStart)
  {
    Perform (theSet, theStart, aRgh);
  }

  if (aLft < theFinal)
  {
    Perform (theSet, aLft, theFinal);
  }
}