0025234: Implementing LBVH builder

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

// 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.

// =======================================================================
// function : Clear
// purpose  :
// =======================================================================
template<class T, int N>
void BVH_Tree<T, N>::Clear()
{
  myDepth = 0;

  BVH::ArrayOp<T, N>::Clear (myMinPointBuffer);
  BVH::ArrayOp<T, N>::Clear (myMaxPointBuffer);

  BVH::ArrayOp<Standard_Integer, 4>::Clear (myNodeInfoBuffer);
}

// =======================================================================
// function : AddLeafNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddLeafNode (const Standard_Integer theBegElem,
                                              const Standard_Integer theEndElem)
{
  BVH::ArrayOp<Standard_Integer, 4>::Append (myNodeInfoBuffer, BVH_Vec4i (1, theBegElem, theEndElem, 0));

  return static_cast<Standard_Integer> (BVH::ArrayOp<Standard_Integer, 4>::Size (myNodeInfoBuffer) - 1);
}

// =======================================================================
// function : AddInnerNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddInnerNode (const Standard_Integer theLftChild,
                                               const Standard_Integer theRghChild)
{
  BVH::ArrayOp<Standard_Integer, 4>::Append (myNodeInfoBuffer, BVH_Vec4i (0, theLftChild, theRghChild, 0));

  return static_cast<Standard_Integer> (BVH::ArrayOp<Standard_Integer, 4>::Size (myNodeInfoBuffer)  - 1);
}

// =======================================================================
// function : AddLeafNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddLeafNode (const BVH_VecNt&       theMinPoint,
                                              const BVH_VecNt&       theMaxPoint,
                                              const Standard_Integer theBegElem,
                                              const Standard_Integer theEndElem)
{
  BVH::ArrayOp<T, N>::Append (myMinPointBuffer, theMinPoint);
  BVH::ArrayOp<T, N>::Append (myMaxPointBuffer, theMaxPoint);

  BVH::ArrayOp<Standard_Integer, 4>::Append (myNodeInfoBuffer, BVH_Vec4i (1, theBegElem, theEndElem, 0));

  return static_cast<Standard_Integer> (BVH::ArrayOp<Standard_Integer, 4>::Size (myNodeInfoBuffer) - 1);
}

// =======================================================================
// function : AddInnerNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddInnerNode (const BVH_VecNt&       theMinPoint,
                                               const BVH_VecNt&       theMaxPoint,
                                               const Standard_Integer theLftChild,
                                               const Standard_Integer theRghChild)
{
  BVH::ArrayOp<T, N>::Append (myMinPointBuffer, theMinPoint);
  BVH::ArrayOp<T, N>::Append (myMaxPointBuffer, theMaxPoint);

  BVH::ArrayOp<Standard_Integer, 4>::Append (myNodeInfoBuffer, BVH_Vec4i (0, theLftChild, theRghChild, 0));

  return static_cast<Standard_Integer> (BVH::ArrayOp<Standard_Integer, 4>::Size (myNodeInfoBuffer)  - 1);
}

// =======================================================================
// function : AddLeafNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddLeafNode (const BVH_Box<T, N>&   theAABB,
                                              const Standard_Integer theBegElem,
                                              const Standard_Integer theEndElem)
{
  return AddLeafNode (theAABB.CornerMin(), theAABB.CornerMax(), theBegElem, theEndElem);
}

// =======================================================================
// function : AddInnerNode
// purpose  :
// =======================================================================
template<class T, int N>
Standard_Integer BVH_Tree<T, N>::AddInnerNode (const BVH_Box<T, N>&   theAABB,
                                               const Standard_Integer theLftChild,
                                               const Standard_Integer theRghChild)
{
  return AddInnerNode (theAABB.CornerMin(), theAABB.CornerMax(), theLftChild, theRghChild);
}

namespace BVH
{
  template<class T, int N>
  void EstimateSAH (const BVH_Tree<T, N>*  theTree,
                    const Standard_Integer theNode,
                    T                      theProbability,
                    T&                     theSAH)
  {
    BVH_Box<T, N> aBox (theTree->MinPoint (theNode),
                        theTree->MaxPoint (theNode));

    if (theTree->IsOuter (theNode))
    {
      theSAH += theProbability * (theTree->EndPrimitive (theNode) - theTree->BegPrimitive (theNode) + 1);
    }
    else
    {
      theSAH += theProbability * static_cast<T> (2.0);

      BVH_Box<T, N> aLftBox (theTree->MinPoint (theTree->LeftChild (theNode)),
                             theTree->MaxPoint (theTree->LeftChild (theNode)));

      if (theProbability > 0.0)
      {
        EstimateSAH (theTree, theTree->LeftChild (theNode),
                     theProbability * aLftBox.Area() / aBox.Area(), theSAH);
      }

      BVH_Box<T, N> aRghBox (theTree->MinPoint (theTree->RightChild (theNode)),
                             theTree->MaxPoint (theTree->RightChild (theNode)));

      if (theProbability > 0.0)
      {
        EstimateSAH (theTree, theTree->RightChild (theNode),
                     theProbability * aRghBox.Area() / aBox.Area(), theSAH);
      }
    }
  }
}

// =======================================================================
// function : EstimateSAH
// purpose  :
// =======================================================================
template<class T, int N>
T BVH_Tree<T, N>::EstimateSAH() const
{
  T aSAH = static_cast<T> (0.0);
  BVH::EstimateSAH (this, 0, static_cast<T> (1.0), aSAH);
  return aSAH;
}