VTK-5.0.0/Filtering/vtkSimpleScalarTree.h

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkSimpleScalarTree.h,v $

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkSimpleScalarTree - organize data according to scalar values (used to accelerate contouring operations)
// .SECTION Description
// vtkSimpleScalarTree creates a pointerless binary tree that helps search for
// cells that lie within a particular scalar range. This object is used to
// accelerate some contouring (and other scalar-based techniques).
// 
// The tree consists of an array of (min,max) scalar range pairs per node in
// the tree. The (min,max) range is determined from looking at the range of
// the children of the tree node. If the node is a leaf, then the range is
// determined by scanning the range of scalar data in n cells in the
// dataset. The n cells are determined by arbitrary selecting cell ids from
// id(i) to id(i+n), and where n is specified using the BranchingFactor
// ivar. Note that leaf node i=0 contains the scalar range computed from
// cell ids (0,n-1); leaf node i=1 contains the range from cell ids (n,2n-1);
// and so on. The implication is that there are no direct lists of cell ids
// per leaf node, instead the cell ids are implicitly known.

#ifndef __vtkSimpleScalarTree_h
#define __vtkSimpleScalarTree_h

#include "vtkScalarTree.h"

//BTX
class vtkScalarNode;
//ETX

class VTK_FILTERING_EXPORT vtkSimpleScalarTree : public vtkScalarTree
{
public:
  // Description:
  // Instantiate scalar tree with maximum level of 20 and branching
  // factor of 5.
  static vtkSimpleScalarTree *New();

  // Description:
  // Standard type related macros and PrintSelf() method.
  vtkTypeRevisionMacro(vtkSimpleScalarTree,vtkScalarTree);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Set the branching factor for the tree. This is the number of
  // children per tree node. Smaller values (minimum is 2) mean deeper
  // trees and more memory overhead. Larger values mean shallower
  // trees, less memory usage, but worse performance.
  vtkSetClampMacro(BranchingFactor,int,2,VTK_LARGE_INTEGER);
  vtkGetMacro(BranchingFactor,int);

  // Description:
  // Get the level of the scalar tree. This value may change each time the
  // scalar tree is built and the branching factor changes.
  vtkGetMacro(Level,int);

  // Description:
  // Set the maximum allowable level for the tree. 
  vtkSetClampMacro(MaxLevel,int,1,VTK_LARGE_INTEGER);
  vtkGetMacro(MaxLevel,int);

  // Description:
  // Construct the scalar tree from the dataset provided. Checks build times
  // and modified time from input and reconstructs the tree if necessary.
  virtual void BuildTree();
  
  // Description:
  // Initialize locator. Frees memory and resets object as appropriate.
  virtual void Initialize();

  // Description:
  // Begin to traverse the cells based on a scalar value. Returned cells
  // will have scalar values that span the scalar value specified.
  virtual void InitTraversal(double scalarValue);

  // Description:
  // Return the next cell that may contain scalar value specified to
  // initialize traversal. The value NULL is returned if the list is
  // exhausted. Make sure that InitTraversal() has been invoked first or
  // you'll get erratic behavior.
  virtual vtkCell *GetNextCell(vtkIdType &cellId, vtkIdList* &ptIds,
                               vtkDataArray *cellScalars);

protected:
  vtkSimpleScalarTree();
  ~vtkSimpleScalarTree();

  vtkDataArray *Scalars;
  int MaxLevel;
  int Level;
  int BranchingFactor; //number of children per node
  vtkScalarNode *Tree; //pointerless scalar range tree
  int TreeSize; //allocated size of tree

private:
  vtkIdType TreeIndex; //traversal location within tree
  vtkIdType LeafOffset; //offset to leaf nodes of tree
  int       ChildNumber; //current child in traversal
  vtkIdType CellId; //current cell id being examined
  int       FindStartLeaf(vtkIdType index, int level);
  int       FindNextLeaf(vtkIdType index,int level);

private:
  vtkSimpleScalarTree(const vtkSimpleScalarTree&);  // Not implemented.
  void operator=(const vtkSimpleScalarTree&);  // Not implemented.
};

#endif