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

  Program:   Visualization Toolkit
  Module:    vtkKdTree.h

  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.

=========================================================================*/
/*----------------------------------------------------------------------------
 Copyright (c) Sandia Corporation
 See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.
----------------------------------------------------------------------------*/

/**
 * @class   vtkKdTree
 * @brief   a Kd-tree spatial decomposition of a set of points
 *
 *
 *     Given one or more vtkDataSets, create a load balancing
 *     k-d tree decomposition of the points at the center of the cells.
 *     Or, create a k-d tree point locator from a list of points.
 *
 *     This class can also generate a PolyData representation of
 *     the boundaries of the spatial regions in the decomposition.
 *
 *     It can sort the regions with respect to a viewing direction,
 *     and it can decompose a list of regions into subsets, each
 *     of which represent a convex spatial region (since many algorithms
 *     require a convex region).
 *
 *     If the points were derived from cells, vtkKdTree
 *     can create a list of cell Ids for each region for each data set.
 *     Two lists are available - all cells with centroid in the region,
 *     and all cells that intersect the region but whose centroid lies
 *     in another region.
 *
 *     For the purpose of removing duplicate points quickly from large
 *     data sets, or for finding nearby points, we added another mode for
 *     building the locator.  BuildLocatorFromPoints will build a k-d tree
 *     from one or more vtkPoints objects.  This can be followed by
 *     BuildMapForDuplicatePoints which returns a mapping from the original
 *     ids to a subset of the ids that is unique within a supplied
 *     tolerance, or you can use FindPoint and FindClosestPoint to
 *     locate points in the original set that the tree was built from.
 *
 * @sa
 *      vtkLocator vtkCellLocator vtkPKdTree
*/

#ifndef vtkKdTree_h
#define vtkKdTree_h

#include "vtkCommonDataModelModule.h" // For export macro
#include "vtkLocator.h"

class vtkTimerLog;
class vtkIdList;
class vtkIdTypeArray;
class vtkIntArray;
class vtkPointSet;
class vtkPoints;
class vtkCellArray;
class vtkCell;
class vtkKdNode;
class vtkBSPCuts;
class vtkBSPIntersections;
class vtkDataSetCollection;

class VTKCOMMONDATAMODEL_EXPORT vtkKdTree : public vtkLocator
{
public:
  vtkTypeMacro(vtkKdTree, vtkLocator);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  static vtkKdTree *New();

  //@{
  /**
   * Turn on timing of the k-d tree build
   */
  vtkBooleanMacro(Timing, vtkTypeBool);
  vtkSetMacro(Timing, vtkTypeBool);
  vtkGetMacro(Timing, vtkTypeBool);
  //@}

  //@{
  /**
   * Minimum number of cells per spatial region.  Default is 100.
   */
  vtkSetMacro(MinCells, int);
  vtkGetMacro(MinCells, int);
  //@}

  /**
   * Set/Get the number of spatial regions you want to get close
   * to without going over.  (The number of spatial regions is normally
   * a power of two.)  Call this before BuildLocator().  Default
   * is unset (0).
   */

  vtkGetMacro(NumberOfRegionsOrLess, int);
  vtkSetMacro(NumberOfRegionsOrLess, int);

  /**
   * Set/Get the number of spatial regions you want to get close
   * to while having at least this many regions.  (The number of
   * spatial regions is normally a power of two.)   Default
   * is unset (0).
   */

  vtkGetMacro(NumberOfRegionsOrMore, int);
  vtkSetMacro(NumberOfRegionsOrMore, int);

  /**
   * Some algorithms on k-d trees require a value that is a very
   * small distance relative to the diameter of the entire space
   * divided by the k-d tree.  This factor is the maximum axis-aligned
   * width of the space multiplied by 10e-6.
   */

  vtkGetMacro(FudgeFactor, double);
  vtkSetMacro(FudgeFactor, double);

  /**
   * Get a vtkBSPCuts object, a general object representing an axis-
   * aligned spatial partitioning.  Used by vtkBSPIntersections.
   */

  vtkGetObjectMacro(Cuts, vtkBSPCuts);

  /**
   * Normally the k-d tree is computed from the dataset(s) provided
   * in SetDataSet.  Alternatively, you can provide the cuts that will
   * be applied by calling SetCuts.
   */

  void SetCuts(vtkBSPCuts *cuts);

  /**
   * Omit partitions along the X axis, yielding shafts in the X direction
   */
  void OmitXPartitioning();

  /**
   * Omit partitions along the Y axis, yielding shafts in the Y direction
   */
  void OmitYPartitioning();

  /**
   * Omit partitions along the Z axis, yielding shafts in the Z direction
   */
  void OmitZPartitioning();

  /**
   * Omit partitions along the X and Y axes, yielding slabs along Z
   */
  void OmitXYPartitioning();

  /**
   * Omit partitions along the Y and Z axes, yielding slabs along X
   */
  void OmitYZPartitioning();

  /**
   * Omit partitions along the Z and X axes, yielding slabs along Y
   */
  void OmitZXPartitioning();

  /**
   * Partition along all three axes - this is the default
   */
  void OmitNoPartitioning();

  /**
   * This class can compute a spatial decomposition based on the
   * cells in a list of one or more input data sets.
   * SetDataSet sets the first data set in the list to the named set.
   * SetNthDataSet sets the data set at index N to the data set named.
   * RemoveData set takes either the data set itself or an index and
   * removes that data set from the list of data sets.
   * AddDataSet adds a data set to the list of data sets.
   */

  /**
   * Clear out all data sets and replace with single data set.  For backward
   * compatibility with superclass.
   */
  void SetDataSet(vtkDataSet *set) override;

  /**
   * This class can compute a spatial decomposition based on the cells in a list
   * of one or more input data sets.  Add them one at a time with this method.
   */
  virtual void AddDataSet(vtkDataSet *set);

  //@{
  /**
   * Remove the given data set.
   */
  virtual void RemoveDataSet(int index);
  virtual void RemoveDataSet(vtkDataSet *set);
  virtual void RemoveAllDataSets();
  //@}

  /**
   * Get the number of data sets included in spatial partitioning
   */
  int GetNumberOfDataSets();

  /**
   * Get the nth defined data set in the spatial partitioning.
   * (If you used SetNthDataSet to define 0,1 and 3 and ask for
   * data set 2, you get 3.)
   */

  /**
   * Return the n'th data set.
   */
  vtkDataSet *GetDataSet(int n);

  /**
   * Return the 0'th data set.  For compatibility with the superclass'
   * interface.
   */
  vtkDataSet *GetDataSet() override { return this->GetDataSet(0); }

  //@{
  /**
   * Return a collection of all the data sets.
   */
  vtkGetObjectMacro(DataSets, vtkDataSetCollection);
  //@}

  /**
   * Return the index of the given data set.  Returns -1 if that data
   * set does not exist.
   */
  int GetDataSetIndex(vtkDataSet *set);

  /**
   * Get the spatial bounds of the entire k-d tree space. Sets
   * bounds array to xmin, xmax, ymin, ymax, zmin, zmax.
   */
  void GetBounds(double *bounds);

  /**
   * There are certain applications where you want the bounds of
   * the k-d tree space to be at least as large as a specified
   * box.  If the k-d tree has been built, you can expand it's
   * bounds with this method.  If the bounds supplied are smaller
   * than those computed, they will be ignored.
   */

  void SetNewBounds(double *bounds);

  //@{
  /**
   * The number of leaf nodes of the tree, the spatial regions
   */
  vtkGetMacro(NumberOfRegions, int);
  //@}

  /**
   * Get the spatial bounds of k-d tree region
   */
  void GetRegionBounds(int regionID, double bounds[6]);

  /**
   * Get the bounds of the data within the k-d tree region
   */
  void GetRegionDataBounds(int regionID, double bounds[6]);

  //@{
  /**
   * Print out nodes of kd tree
   */
  void PrintTree();
  void PrintVerboseTree();
  //@}

  /**
   * Print out leaf node data for given id
   */
  void PrintRegion(int id);

  /**
   * Create a list for each of the requested regions, listing
   * the IDs of all cells whose centroid falls in the region.
   * These lists are obtained with GetCellList().
   * If no DataSet is specified, the cell list is created
   * for DataSet 0.  If no list of requested regions is provided,
   * the cell lists for all regions are created.

   * When CreateCellLists is called again, the lists created
   * on the previous call are deleted.
   */

  void CreateCellLists(int dataSetIndex, int *regionReqList,
                       int reqListSize);
  void CreateCellLists(vtkDataSet *set, int *regionReqList,
                       int reqListSize);
  void CreateCellLists(int *regionReqList, int listSize);
  void CreateCellLists();

  //@{
  /**
   * If IncludeRegionBoundaryCells is ON,
   * CreateCellLists() will also create a list of cells which
   * intersect a given region, but are not assigned
   * to the region.  These lists are obtained with
   * GetBoundaryCellList().  Default is OFF.
   */
  vtkSetMacro(IncludeRegionBoundaryCells, vtkTypeBool);
  vtkGetMacro(IncludeRegionBoundaryCells, vtkTypeBool);
  vtkBooleanMacro(IncludeRegionBoundaryCells, vtkTypeBool);
  //@}

  /**
   * Free the memory used by the cell lists.
   */
  void DeleteCellLists();

  /**
   * Get the cell list for a region.  This returns a pointer
   * to vtkKdTree's memory, so don't free it.
   */
  vtkIdList *GetCellList(int regionID);

  /**
   * The cell list obtained with GetCellList is the list
   * of all cells such that their centroid is contained in
   * the spatial region.  It may also be desirable to get
   * a list of all cells intersecting a spatial region,
   * but with centroid in some other region.  This is that
   * list.  This list is computed in CreateCellLists() if
   * and only if IncludeRegionBoundaryCells is ON.  This
   * returns a pointer to KdTree's memory, so don't free it.
   */
  vtkIdList *GetBoundaryCellList(int regionID);

  //@{
  /**

   * For a list of regions, get two cell lists.  The first lists
   * the IDs all cells whose centroids lie in one of the regions.
   * The second lists the IDs of all cells that intersect the regions,
   * but whose centroid lies in a region not on the list.

   * The total number of cell IDs written to both lists is returned.
   * Either list pointer passed in can be nullptr, and it will be ignored.
   * If there are multiple data sets, you must specify which data set
   * you wish cell IDs for.

   * The caller should delete these two lists when done.  This method
   * uses the cell lists created in CreateCellLists().
   * If the cell list for any of the requested regions does not
   * exist, then this method will call CreateCellLists() to create
   * cell lists for *every* region of the k-d tree.  You must remember
   * to DeleteCellLists() when done with all calls to this method, as
   * cell lists can require a great deal of memory.
   */
  vtkIdType GetCellLists(vtkIntArray *regions, int set,
                   vtkIdList *inRegionCells, vtkIdList *onBoundaryCells);
  vtkIdType GetCellLists(vtkIntArray *regions, vtkDataSet *set,
            vtkIdList *inRegionCells, vtkIdList *onBoundaryCells);
  vtkIdType GetCellLists(vtkIntArray *regions, vtkIdList *inRegionCells,
                                    vtkIdList *onBoundaryCells);
  //@}

  //@{
  /**
   * Get the id of the region containing the cell centroid.  If
   * no DataSet is specified, assume DataSet 0.  If you need the
   * region ID for every cell, use AllGetRegionContainingCell
   * instead.  It is more efficient.
   */
  int GetRegionContainingCell(vtkDataSet *set, vtkIdType cellID);
  int GetRegionContainingCell(int set, vtkIdType cellID);
  int GetRegionContainingCell(vtkIdType cellID);
  //@}

  /**
   * Get a list (in order by data set by cell id) of the
   * region IDs of the region containing the centroid for
   * each cell.
   * This is faster than calling GetRegionContainingCell
   * for each cell in the DataSet.
   * vtkKdTree uses this list, so don't delete it.
   */
  int *AllGetRegionContainingCell();

  /**
   * Get the id of the region containing the specified location.
   */
  int GetRegionContainingPoint(double x, double y, double z);

  /**
   * Create the k-d tree decomposition of the cells of the data set
   * or data sets.  Cells are assigned to k-d tree spatial regions
   * based on the location of their centroids.
   */
  void BuildLocator() override;

  /**
   * Given a list of region IDs, determine the decomposition of
   * these regions into the minimal number of convex subregions.  Due
   * to the way the k-d tree is constructed, those convex subregions
   * will be axis-aligned boxes.  Return the minimal number of
   * such convex regions that compose the original region list.
   * This call will set convexRegionBounds to point to a list
   * of the bounds of these regions.  Caller should free this.
   * There will be six values for each convex subregion (xmin,
   * xmax, ymin, ymax, zmin, zmax).  If the regions in the
   * regionIdList form a box already, a "1" is returned and the
   * second argument contains the bounds of the box.
   */

  int MinimalNumberOfConvexSubRegions(vtkIntArray *regionIdList,
                                      double **convexRegionBounds);

  /**
   * Given a direction of projection (typically obtained with
   * vtkCamera::GetDirectionOfProjection()), this method, creates a list of the
   * k-d tree region IDs in order from front to back with respect to that
   * direction.  The number of ordered regions is returned.  Use this method to
   * view order regions for cameras that use parallel projection.
   */
  int ViewOrderAllRegionsInDirection(const double directionOfProjection[3],
                                     vtkIntArray *orderedList);

  /**
   * Given a direction of projection and a list of k-d tree region IDs, this
   * method, creates a list of the k-d tree region IDs in order from front to
   * back with respect to that direction.  The number of ordered regions is
   * returned.  Use this method to view order regions for cameras that use
   * parallel projection.
   */
  int ViewOrderRegionsInDirection(vtkIntArray *regionIds,
                                  const double directionOfProjection[3],
                                  vtkIntArray *orderedList);

  /**
   * Given a camera position (typically obtained with vtkCamera::GetPosition()),
   * this method, creates a list of the k-d tree region IDs in order from front
   * to back with respect to that direction.  The number of ordered regions is
   * returned.  Use this method to view order regions for cameras that use
   * perspective projection.
   */
  int ViewOrderAllRegionsFromPosition(const double directionOfProjection[3],
                                      vtkIntArray *orderedList);

  /**
   * Given a camera position and a list of k-d tree region IDs, this method,
   * creates a list of the k-d tree region IDs in order from front to back with
   * respect to that direction.  The number of ordered regions is returned.  Use
   * this method to view order regions for cameras that use perspective
   * projection.
   */
  int ViewOrderRegionsFromPosition(vtkIntArray *regionIds,
                                   const double directionOfProjection[3],
                                   vtkIntArray *orderedList);

  //@{
  /**
   * This is a special purpose locator that builds a k-d tree to
   * find duplicate and near-by points.  It builds the tree from
   * one or more vtkPoints objects instead of from the cells of
   * a vtkDataSet.  This build would normally be followed by
   * BuildMapForDuplicatePoints, FindPoint, or FindClosestPoint.
   * Since this will build a normal k-d tree, all the region intersection
   * queries will still work, as will most other calls except those that
   * have "Cell" in the name.

   * This method works most efficiently when the point arrays are
   * float arrays.
   */
  void BuildLocatorFromPoints(vtkPointSet *pointset);
  void BuildLocatorFromPoints(vtkPoints *ptArray);
  void BuildLocatorFromPoints(vtkPoints **ptArray, int numPtArrays);
  //@}

  /**
   * This call returns a mapping from the original point IDs supplied
   * to BuildLocatorFromPoints to a subset of those IDs that is unique
   * within the specified tolerance.
   * If points 2, 5, and 12 are the same, then
   * IdMap[2] = IdMap[5] = IdMap[12] = 2 (or 5 or 12).

   * "original point IDs" - For point IDs we start at 0 for the first
   * point in the first vtkPoints object, and increase by 1 for subsequent
   * points and subsequent vtkPoints objects.

   * You must have called BuildLocatorFromPoints() before calling this.
   * You are responsible for deleting the returned array.
   */
  vtkIdTypeArray *BuildMapForDuplicatePoints(float tolerance);

  //@{
  /**
   * Find the Id of the point that was previously supplied
   * to BuildLocatorFromPoints().  Returns -1 if the point
   * was not in the original array.
   */
  vtkIdType FindPoint(double *x);
  vtkIdType FindPoint(double x, double y, double z);
  //@}

  //@{
  /**
   * Find the Id of the point that was previously supplied
   * to BuildLocatorFromPoints() which is closest to the given point.
   * Set the square of the distance between the two points.
   */
  vtkIdType FindClosestPoint(double *x, double &dist2);
  vtkIdType FindClosestPoint(double x, double y, double z, double &dist2);
  //@}

  /**
   * Given a position x and a radius r, return the id of the point
   * closest to the point in that radius.
   * dist2 returns the squared distance to the point.
   */
  vtkIdType FindClosestPointWithinRadius(
    double radius, const double x[3], double& dist2);

  //@{
  /**
   * Find the Id of the point in the given region which is
   * closest to the given point.  Return the ID of the point,
   * and set the square of the distance of between the points.
   */
  vtkIdType FindClosestPointInRegion(int regionId, double *x, double &dist2);
  vtkIdType FindClosestPointInRegion(int regionId, double x, double y, double z,
                                     double &dist2);
  //@}

  /**
   * Find all points within a specified radius R of position x.
   * The result is not sorted in any specific manner.
   * These methods are thread safe if BuildLocator() is directly or
   * indirectly called from a single thread first.
   */
  void FindPointsWithinRadius(double R, const double x[3], vtkIdList *result);

  /**
   * Find the closest N points to a position. This returns the closest
   * N points to a position. A faster method could be created that returned
   * N close points to a position, but necessarily the exact N closest.
   * The returned points are sorted from closest to farthest.
   * These methods are thread safe if BuildLocator() is directly or
   * indirectly called from a single thread first.
   */
  void FindClosestNPoints(int N, const double x[3], vtkIdList *result);

  /**
   * Get a list of the original IDs of all points in a region.  You
   * must have called BuildLocatorFromPoints before calling this.
   */
  vtkIdTypeArray *GetPointsInRegion(int regionId);

  /**
   * Delete the k-d tree data structure. Also delete any
   * cell lists that were computed with CreateCellLists().
   */
  void FreeSearchStructure() override;

  /**
   * Create a polydata representation of the boundaries of
   * the k-d tree regions.  If level equals GetLevel(), the
   * leaf nodes are represented.
   */
  void GenerateRepresentation(int level, vtkPolyData *pd) override;

  /**
   * Generate a polygonal representation of a list of regions.
   * Only leaf nodes have region IDs, so these will be leaf nodes.
   */
  void GenerateRepresentation(int *regionList, int len, vtkPolyData *pd);

  //@{
  /**
   * The polydata representation of the k-d tree shows the boundaries
   * of the k-d tree decomposition spatial regions.  The data inside
   * the regions may not occupy the entire space.  To draw just the
   * bounds of the data in the regions, set this variable ON.
   */
  vtkBooleanMacro(GenerateRepresentationUsingDataBounds, vtkTypeBool);
  vtkSetMacro(GenerateRepresentationUsingDataBounds, vtkTypeBool);
  vtkGetMacro(GenerateRepresentationUsingDataBounds, vtkTypeBool);
  //@}

  /**
   * Print timing of k-d tree build
   */
  virtual void PrintTiming(ostream& os, vtkIndent indent);

  /**
   * Return 1 if the geometry of the input data sets
   * has changed since the last time the k-d tree was built.
   */
  virtual int NewGeometry();

  /**
   * Return 1 if the geometry of these data sets differs
   * for the geometry of the last data sets used to build
   * the k-d tree.
   */
  virtual int NewGeometry(vtkDataSet **sets, int numDataSets);

  /**
   * Forget about the last geometry used.  The next call to NewGeometry will
   * return 1.  A new k-d tree will be built the next time BuildLocator is
   * called.
   */
  virtual void InvalidateGeometry();

  /**
   * Create a copy of the binary tree representation of the
   * k-d tree spatial partitioning provided.
   */

  static vtkKdNode *CopyTree(vtkKdNode *kd);

  /**
   * Fill ids with points found in area.  The area is a 6-tuple containing
   * (xmin, xmax, ymin, ymax, zmin, zmax).
   * This method will clear the array by default.  To append ids to an array,
   * set clearArray to false.
   */
  void FindPointsInArea(double* area, vtkIdTypeArray* ids, bool clearArray = true);

protected:

  vtkKdTree();
  ~vtkKdTree() override;

  vtkBSPIntersections *BSPCalculator;
  int UserDefinedCuts;

  void SetCalculator(vtkKdNode *kd);

  int ProcessUserDefinedCuts(double *bounds);

  void SetCuts(vtkBSPCuts *cuts, int userDefined);

  /**
   * Save enough state so NewGeometry() can work,
   * and update the BuildTime time stamp.
   */

  void UpdateBuildTime();

  /**
   * Prior to dividing a region at level "level", of size
   * "numberOfPoints", apply the tests implied by MinCells,
   * NumberOfRegionsOrMore and NumberOfRegionsOrLess.  Return 1 if it's
   * OK to divide the region, 0 if you should not.
   */

  int DivideTest(int numberOfPoints, int level);

  enum {
    XDIM = 0,  // don't change these values
    YDIM = 1,
    ZDIM = 2
  };

  int ValidDirections;

  vtkKdNode *Top;
  vtkKdNode **RegionList;      // indexed by region ID

  vtkTimerLog *TimerLog;

  static void DeleteAllDescendants(vtkKdNode *nd);

  void BuildRegionList();
  virtual int SelectCutDirection(vtkKdNode *kd);
  void SetActualLevel(){this->Level = vtkKdTree::ComputeLevel(this->Top);}

  /**
   * Get back a list of the nodes at a specified level, nodes must
   * be preallocated to hold 2^^(level) node structures.
   */

  void GetRegionsAtLevel(int level, vtkKdNode **nodes);

  /**
   * Adds to the vtkIntArray the list of region IDs of all leaf
   * nodes in the given node.
   */

  static void GetLeafNodeIds(vtkKdNode *node, vtkIntArray *ids);


  /**
   * Returns the total number of cells in all the data sets
   */

  int GetNumberOfCells();

  /**
   * Returns the total number of cells in data set 1 through
   * data set 2.
   */

  int GetDataSetsNumberOfCells(int set1, int set2);

  /**
   * Get or compute the center of one cell.  If the DataSet is
   * nullptr, the first DataSet is used.  This is the point used in
   * determining to which spatial region the cell is assigned.
   */

  void ComputeCellCenter(vtkDataSet *set, int cellId, float *center);
  void ComputeCellCenter(vtkDataSet *set, int cellId, double *center);

  /**
   * Compute and return a pointer to a list of all cell centers,
   * in order by data set by cell Id.  If a DataSet is specified
   * cell centers for cells of that data only are returned.  If
   * no DataSet is specified, the cell centers of cells in all
   * DataSets are returned.  The caller should free the list of
   * cell centers when done.
   */

  float *ComputeCellCenters();
  float *ComputeCellCenters(int set);
  float *ComputeCellCenters(vtkDataSet *set);

  vtkDataSetCollection *DataSets;

  /**
   * Modelled on vtkAlgorithm::UpdateProgress().
   * Update the progress when building the locator.
   * Fires vtkCommand::ProgressEvent.
   */
  void UpdateProgress(double amount);

  //@{
  /**
   * Set/Get the execution progress of a process object.
   */
  vtkSetClampMacro(Progress,double,0.0,1.0);
  vtkGetMacro(Progress,double);
  //@}

protected:
  // So that each suboperation can report progress
  // in [0,1], yet we will be able to report a global
  // progress. Sub-operations must use UpdateSubOperationProgress()
  // for this to work.
  double ProgressScale;
  double ProgressOffset;

  // Update progress for a sub-operation. \c amount goes from 0.0 to 1.0.
  // Actual progress is given by
  // (this->ProgressOffset + this->ProgressScale* amount).
  void UpdateSubOperationProgress(double amount);

  static void _SetNewBounds(vtkKdNode *kd, double *b, int *fixDim);
  static void CopyChildNodes(vtkKdNode *to, vtkKdNode *from);
  static void CopyKdNode(vtkKdNode *to, vtkKdNode *from);
  static void SetDataBoundsToSpatialBounds(vtkKdNode *kd);
  static void ZeroNumberOfPoints(vtkKdNode *kd);

  // Recursive helper for public FindPointsWithinRadius
  void FindPointsWithinRadius(vtkKdNode* node, double R2,
                              const double x[3], vtkIdList* ids);

  // Recursive helper for public FindPointsWithinRadius
  void AddAllPointsInRegion(vtkKdNode* node, vtkIdList* ids);

  // Recursive helper for public FindPointsInArea
  void FindPointsInArea(vtkKdNode* node, double* area, vtkIdTypeArray* ids);

  // Recursive helper for public FindPointsInArea
  void AddAllPointsInRegion(vtkKdNode* node, vtkIdTypeArray* ids);

  int DivideRegion(vtkKdNode *kd, float *c1, int *ids, int nlevels);

  void DoMedianFind(vtkKdNode *kd, float *c1, int *ids, int d1, int d2, int d3);

  void SelfRegister(vtkKdNode *kd);

  struct _cellList{
    vtkDataSet *dataSet;        // cell lists for which data set
    int *regionIds;            // nullptr if listing all regions
    int nRegions;
    vtkIdList **cells;
    vtkIdList **boundaryCells;
    vtkIdList *emptyList;
  };

  void InitializeCellLists();
  vtkIdList *GetList(int regionId, vtkIdList **which);

  void ComputeCellCenter(vtkCell* cell, double *center, double *weights);

  void GenerateRepresentationDataBounds(int level, vtkPolyData *pd);
  void _generateRepresentationDataBounds(vtkKdNode *kd, vtkPoints *pts,
                                         vtkCellArray *polys, int level);

  void GenerateRepresentationWholeSpace(int level, vtkPolyData *pd);
  void _generateRepresentationWholeSpace(vtkKdNode *kd, vtkPoints *pts,
                                         vtkCellArray *polys, int level);

  void AddPolys(vtkKdNode *kd, vtkPoints *pts, vtkCellArray *polys);

  void _printTree(int verbose);

  int SearchNeighborsForDuplicate(int regionId, float *point,
                                  int **pointsSoFar, int *len,
                                  float tolerance, float tolerance2);

  int SearchRegionForDuplicate(float *point, int *pointsSoFar,
                               int len, float tolerance2);

  int _FindClosestPointInRegion(int regionId,
                          double x, double y, double z, double &dist2);

  int FindClosestPointInSphere(double x, double y, double z, double radius,
                               int skipRegion, double &dist2);

  int _ViewOrderRegionsInDirection(vtkIntArray *IdsOfInterest,
                                   const double dop[3],
                                   vtkIntArray *orderedList);

  static int __ViewOrderRegionsInDirection(vtkKdNode *node, vtkIntArray *list,
                                           vtkIntArray *IdsOfInterest,
                                           const double dir[3], int nextId);

  int _ViewOrderRegionsFromPosition(vtkIntArray *IdsOfInterest,
                                    const double pos[3],
                                    vtkIntArray *orderedList);

  static int __ViewOrderRegionsFromPosition(vtkKdNode *node, vtkIntArray *list,
                                            vtkIntArray *IdsOfInterest,
                                            const double pos[3], int nextId);

  static int __ConvexSubRegions(int *ids, int len, vtkKdNode *tree, vtkKdNode **nodes);
  static int FoundId(vtkIntArray *idArray, int id);

  void SetInputDataInfo(int i,
       int dims[3], double origin[3], double spacing[3]);
  int CheckInputDataInfo(int i,
       int dims[3], double origin[3], double spacing[3]);
  void ClearLastBuildCache();

  static void __printTree(vtkKdNode *kd, int depth, int verbose);

  static int MidValue(int dim, float *c1, int nvals, double &coord);

  static int Select(int dim, float *c1, int *ids, int nvals, double &coord);
  static float FindMaxLeftHalf(int dim, float *c1, int K);
  static void _Select(int dim, float *X, int *ids, int L, int R, int K);

  static int ComputeLevel(vtkKdNode *kd);
  static int SelfOrder(int id, vtkKdNode *kd);
  static int findRegion(vtkKdNode *node, float x, float y, float z);
  static int findRegion(vtkKdNode *node, double x, double y, double z);

  static vtkKdNode **_GetRegionsAtLevel(int level, vtkKdNode **nodes,
                                        vtkKdNode *kd);

  static void AddNewRegions(vtkKdNode *kd, float *c1,
                            int midpt, int dim, double coord);

  void NewPartitioningRequest(int req);

  int NumberOfRegionsOrLess;
  int NumberOfRegionsOrMore;

  vtkTypeBool IncludeRegionBoundaryCells;
  double CellBoundsCache[6];       // to optimize IntersectsCell()

  vtkTypeBool GenerateRepresentationUsingDataBounds;

  struct _cellList CellList;

  // Region Ids, by data set by cell id - this list is large (one
  // int per cell) but accelerates creation of cell lists

  int *CellRegionList;

  int MinCells;
  int NumberOfRegions;              // number of leaf nodes

  vtkTypeBool Timing;
  double FudgeFactor;   // a very small distance, relative to the dataset's size

  // These instance variables are used by the special locator created
  // to find duplicate points. (BuildLocatorFromPoints)

  int NumberOfLocatorPoints;
  float *LocatorPoints;
  int *LocatorIds;
  int *LocatorRegionLocation;

  float MaxWidth;

  // These Last* values are here to save state so we can
  // determine later if k-d tree must be rebuilt.

  int LastNumDataSets;
  int LastDataCacheSize;
  vtkDataSet **LastInputDataSets;
  unsigned long *LastDataSetObserverTags;
  int *LastDataSetType;
  double *LastInputDataInfo;
  double *LastBounds;
  vtkIdType *LastNumPoints;
  vtkIdType *LastNumCells;

  vtkBSPCuts *Cuts;
  double Progress;

  vtkKdTree(const vtkKdTree&) = delete;
  void operator=(const vtkKdTree&) = delete;
};
#endif
