vtkCellLocator.h

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

  Program:   Visualization Toolkit
  Module:    vtkCellLocator.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.

=========================================================================*/
// .NAME vtkCellLocator - octree-based spatial search object to quickly locate cells
// .SECTION Description
// vtkCellLocator is a spatial search object to quickly locate cells in 3D.
// vtkCellLocator uses a uniform-level octree subdivision, where each octant
// (an octant is also referred to as a bucket) carries an indication of
// whether it is empty or not, and each leaf octant carries a list of the
// cells inside of it. (An octant is not empty if it has one or more cells
// inside of it.)  Typical operations are intersection with a line to return
// candidate cells, or intersection with another vtkCellLocator to return
// candidate cells.

// .SECTION Caveats
// Many other types of spatial locators have been developed, such as 
// variable depth octrees and kd-trees. These are often more efficient 
// for the operations described here. vtkCellLocator has been designed
// for subclassing; so these locators can be derived if necessary.

// .SECTION See Also
// vtkLocator vtkPointLocator vtkOBBTree

#ifndef __vtkCellLocator_h
#define __vtkCellLocator_h

#include "vtkAbstractCellLocator.h"

class vtkNeighborCells;

class VTK_FILTERING_EXPORT vtkCellLocator : public vtkAbstractCellLocator
{
public:
  vtkTypeMacro(vtkCellLocator,vtkAbstractCellLocator);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Construct with automatic computation of divisions, averaging
  // 25 cells per bucket.
  static vtkCellLocator *New();

  // Description:
  // Specify the average number of cells in each octant.
  void SetNumberOfCellsPerBucket(int N) 
  { this->SetNumberOfCellsPerNode(N); }
  int GetNumberOfCellsPerBucket()  
  { return this->NumberOfCellsPerNode; }

//BTX
/*
  if the borland compiler is ever removed, we can use these declarations
  instead of reimplementaing the calls in this subclass
  using vtkAbstractCellLocator::IntersectWithLine;
  using vtkAbstractCellLocator::FindClosestPoint;
  using vtkAbstractCellLocator::FindClosestPointWithinRadius;
*/
//ETX

  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual int IntersectWithLine(
    double a0[3], double a1[3], double tol,
    double& t, double x[3], double pcoords[3],
    int &subId) 
  {
    return Superclass::
      IntersectWithLine(a0, a1, tol,t, x, pcoords, subId);
  }

  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual int IntersectWithLine(
    double a0[3], double a1[3], double tol,
    double& t, double x[3], double pcoords[3],
    int &subId, vtkIdType &cellId)
  {
    return Superclass::
      IntersectWithLine(a0, a1, tol,t, x, pcoords, subId, cellId);
  }

  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual int IntersectWithLine(
    const double a0[3], const double a1[3],
    vtkPoints *points, vtkIdList *cellIds)
  {
    return Superclass::
      IntersectWithLine(a0, a1, points, cellIds);
  }

  // Description:
  // Return intersection point (if any) AND the cell which was intersected by
  // the finite line. The cell is returned as a cell id and as a generic cell.
  // For other IntersectWithLine signatures, see vtkAbstractCellLocator
  virtual int IntersectWithLine(double a0[3], double a1[3], double tol,
                                double& t, double x[3], double pcoords[3],
                                int &subId, vtkIdType &cellId,
                                vtkGenericCell *cell);

  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual void FindClosestPoint(
    double x[3], double closestPoint[3],
    vtkIdType &cellId, int &subId, double& dist2)
  {
    Superclass::
      FindClosestPoint(x, closestPoint, cellId, subId, dist2);
  }
  
  // Description:
  // Return the closest point and the cell which is closest to the point x.
  // The closest point is somewhere on a cell, it need not be one of the
  // vertices of the cell.  This version takes in a vtkGenericCell
  // to avoid allocating and deallocating the cell.  This is much faster than
  // the version which does not take a *cell, especially when this function is
  // called many times in a row such as by a for loop, where the allocation and
  // deallocation can be done only once outside the for loop.  If a cell is
  // found, "cell" contains the points and ptIds for the cell "cellId" upon
  // exit.
  virtual void FindClosestPoint(
    double x[3], double closestPoint[3],
    vtkGenericCell *cell, vtkIdType &cellId, 
    int &subId, double& dist2);

  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual vtkIdType FindClosestPointWithinRadius(
    double x[3], double radius,
    double closestPoint[3], vtkIdType &cellId,
    int &subId, double& dist2)
  {
    return Superclass::FindClosestPointWithinRadius
      (x, radius, closestPoint, cellId, subId, dist2);
  }
 
  // Description:
  // reimplemented from vtkAbstractCellLocator to support bad compilers
  virtual vtkIdType FindClosestPointWithinRadius(
    double x[3], double radius,
    double closestPoint[3],
    vtkGenericCell *cell, vtkIdType &cellId,
    int &subId, double& dist2)
  {
    return Superclass::FindClosestPointWithinRadius
      (x, radius, closestPoint, cell, cellId, subId, dist2);
  }

  // Description:
  // Return the closest point within a specified radius and the cell which is
  // closest to the point x. The closest point is somewhere on a cell, it
  // need not be one of the vertices of the cell. This method returns 1 if a
  // point is found within the specified radius. If there are no cells within
  // the specified radius, the method returns 0 and the values of
  // closestPoint, cellId, subId, and dist2 are undefined. This version takes
  // in a vtkGenericCell to avoid allocating and deallocating the cell.  This
  // is much faster than the version which does not take a *cell, especially
  // when this function is called many times in a row such as by a for loop,
  // where the allocation and dealloction can be done only once outside the
  // for loop.  If a closest point is found, "cell" contains the points and
  // ptIds for the cell "cellId" upon exit.  If a closest point is found,
  // inside returns the return value of the EvaluatePosition call to the
  // closest cell; inside(=1) or outside(=0).
  // For other FindClosestPointWithinRadius signatures, see vtkAbstractCellLocator
  virtual vtkIdType FindClosestPointWithinRadius(
    double x[3], double radius, double closestPoint[3],
    vtkGenericCell *cell, vtkIdType &cellId,
    int &subId, double& dist2, int &inside);
  
  // Description:
  // Get the cells in a particular bucket.
  virtual vtkIdList *GetCells(int bucket);

  // Description:
  // Return number of buckets available. Insure that the locator has been 
  // built before attempting to access buckets (octants).
  virtual int GetNumberOfBuckets(void);

  // Description:
  // Returns the Id of the cell containing the point, 
  // returns -1 if no cell found. This interface uses a tolerance of zero
  virtual vtkIdType FindCell(double x[3])
    { return this->Superclass::FindCell(x); }

  // Description:
  // Find the cell containing a given point. returns -1 if no cell found
  // the cell parameters are copied into the supplied variables, a cell must
  // be provided to store the information.
  virtual vtkIdType FindCell(
    double x[3], double tol2, vtkGenericCell *GenCell, 
    double pcoords[3], double *weights);

  // Description:
  // Return a list of unique cell ids inside of a given bounding box. The
  // user must provide the vtkIdList to populate. This method returns data
  // only after the locator has been built.
  virtual void FindCellsWithinBounds(double *bbox, vtkIdList *cells);

  // Description:
  // Given a finite line defined by the two points (p1,p2), return the list
  // of unique cell ids in the buckets containing the line. It is possible
  // that an empty cell list is returned. The user must provide the vtkIdList
  // to populate. This method returns data only after the locator has been
  // built.
  virtual void FindCellsAlongLine(
    double p1[3], double p2[3], double tolerance, vtkIdList *cells);

  // Description:
  // Satisfy vtkLocator abstract interface.
  virtual void FreeSearchStructure();
  virtual void BuildLocator();
  virtual void BuildLocatorIfNeeded();
  virtual void ForceBuildLocator();
  virtual void BuildLocatorInternal();
  virtual void GenerateRepresentation(int level, vtkPolyData *pd);
  
protected:
  vtkCellLocator();
  ~vtkCellLocator();

  void GetBucketNeighbors(int ijk[3], int ndivs, int level);
  void GetOverlappingBuckets(double x[3], int ijk[3], double dist, 
                             int prevMinLevel[3], int prevMaxLevel[3]);

  void ClearCellHasBeenVisited();
  void ClearCellHasBeenVisited(int id);

  double Distance2ToBucket(double x[3], int nei[3]);
  double Distance2ToBounds(double x[3], double bounds[6]);
  
  int NumberOfOctants; // number of octants in tree
  double Bounds[6]; // bounding box root octant
  int NumberOfParents; // number of parent octants
  double H[3]; // width of leaf octant in x-y-z directions
  int NumberOfDivisions; // number of "leaf" octant sub-divisions
  vtkIdList **Tree; // octree

  void MarkParents(void*, int, int, int, int, int);
  void GetChildren(int idx, int level, int children[8]);
  int GenerateIndex(int offset, int numDivs, int i, int j, int k,
                    vtkIdType &idx);
  void GenerateFace(int face, int numDivs, int i, int j, int k,
                    vtkPoints *pts, vtkCellArray *polys);

  vtkNeighborCells *Buckets;
  unsigned char *CellHasBeenVisited;
  unsigned char QueryNumber;

  void ComputeOctantBounds(int i, int j, int k);
  double OctantBounds[6]; //the bounds of the current octant
  int IsInOctantBounds(double x[3])
    {
    if ( this->OctantBounds[0] <= x[0] && x[0] <= this->OctantBounds[1] &&
         this->OctantBounds[2] <= x[1] && x[1] <= this->OctantBounds[3] &&
         this->OctantBounds[4] <= x[2] && x[2] <= this->OctantBounds[5] )
      {
      return 1;
      }
    else
      {
      return 0;
      }
    }

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

#endif