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

  Program:   Visualization Toolkit
  Module:    vtkScalarTree.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-2000 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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   of any contributors may be used to endorse or promote products derived
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=========================================================================*/
// .NAME vtkScalarTree - organize data according to scalar values (used to accelerate contouring operations)
// .SECTION Description
// vtkScalarTree 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-baed 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 __vtkScalarTree_h
#define __vtkScalarTree_h

#include "vtkObject.h"
#include "vtkDataSet.h"

typedef struct _vtkScalarRange
{
  float min;
  float max;
} vtkScalarRange;


class VTK_EXPORT vtkScalarTree : public vtkObject
{
public:
  vtkTypeMacro(vtkScalarTree,vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent);

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

  // Description:
  // Build the tree from the points/cells defining this dataset.
  vtkSetObjectMacro(DataSet,vtkDataSet);
  vtkGetObjectMacro(DataSet,vtkDataSet);

  // 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 locator (determined automatically if Automatic is 
  // true). The value of this ivar may change each time the locator is built.
  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 necessaery.
  void BuildTree();
  
  // Description:
  // Initialize locator. Frees memory and resets object as appropriate.
  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.
  void InitTraversal(float 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.
  vtkCell *GetNextCell(int &cellId, vtkIdList* &ptIds,
                       vtkScalars *cellScalars);

  // Description:
  // For legacy compatibiltiy. Do not use.
  vtkCell *GetNextCell(int& cellId, vtkIdList* &ptIds,
                       vtkScalars& cellScalars) 
    {return this->GetNextCell(cellId, ptIds, &cellScalars);}
  
  
    

protected:
  vtkScalarTree();
  ~vtkScalarTree();
  vtkScalarTree(const vtkScalarTree&) {};
  void operator=(const vtkScalarTree&) {};

  vtkDataSet *DataSet;
  vtkScalars *Scalars;
  int MaxLevel;
  int Level;
  int BranchingFactor; //number of children per node

  vtkScalarRange *Tree; //pointerless scalar range tree
  int TreeSize; //allocated size of tree
  vtkTimeStamp BuildTime; //time at which tree was built

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

#endif


