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

  Program:   Visualization Toolkit
  Module:    vtkStaticCellLinksTemplate.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 vtkStaticCellLinksTemplate - object represents upward pointers from points
// to list of cells using each point (template implementation)

// .SECTION Description
// vtkStaticCellLinksTemplate is a supplemental object to vtkCellArray and
// vtkCellTypes, enabling access from points to the cells using the
// points. vtkStaticCellLinksTemplate is an array of links, each link represents a
// list of cell ids using a particular point. The information provided by
// this object can be used to determine neighbors and construct other local
// topological information. This class is a faster implementation of
// vtkCellLinks. However, it cannot be incrementally constructed; it is meant
// to be constructed once (statically) and must be rebuilt if the cells
// change.
//
// This is a templated implementation for vtkStaticCellLinks. The reason for
// the templating is to gain performance and reduce memory by using smaller
// integral types to represent ids. For example, if the maximum id can be
// represented by an int (as compared to a vtkIdType), it is possible to
// reduce memory requirements by half and increase performance up to
// 30%. This templated class can be used directly; alternatively the
// non-templated class vtkStaticCellLinks can be used for convenience;
// although it uses vtkIdType and thereby loses some speed and memory
// advantage.

// .SECTION See Also
// vtkCellLinks vtkStaticCellLinks

#ifndef vtkStaticCellLinksTemplate_h
#define vtkStaticCellLinksTemplate_h

class vtkDataSet;
class vtkPolyData;
class vtkUnstructuredGrid;
class vtkCellArray;


template <typename TIds>
class vtkStaticCellLinksTemplate
{
public:
  // Description:
  // Default constructor. BuildLinks() does most of the work.
  vtkStaticCellLinksTemplate() :
    LinksSize(0), NumPts(0), NumCells(0), Links(NULL), Offsets(NULL)
    {
    }

  // Description:
  // Virtual destructor, anticipating future subclassing.
  virtual ~vtkStaticCellLinksTemplate()
    {this->Initialize();}

  // Description:
  // Make sure any previously created links are cleaned up.
  virtual void Initialize();

  // Description:
  // Build the link list array. Satisfy superclass' API.
  virtual void BuildLinks(vtkDataSet *ds);

  // Description:
  // Build the link list array for vtkPolyData.
  void BuildLinks(vtkPolyData *pd);

  // Description:
  // Build the link list array for vtkUnstructuredGrid.
  void BuildLinks(vtkUnstructuredGrid *ugrid);

  // Description:
  // Get the number of cells using the point specified by ptId.
  TIds GetNumberOfCells(vtkIdType ptId)
    {
      return (this->Offsets[ptId+1] - this->Offsets[ptId]);
    }

  // Description:
  // Return a list of cell ids using the point.
  const TIds *GetCells(vtkIdType ptId)
    {
      return this->Links + this->Offsets[ptId];
    }

protected:
  // The various templated data members
  TIds LinksSize;
  TIds NumPts;
  TIds NumCells;

  // These point to the core data structures
  TIds *Links; //contiguous runs of cell ids
  TIds *Offsets; //offsets for each point into the link array

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

};

#include "vtkStaticCellLinksTemplate.txx"

#endif
// VTK-HeaderTest-Exclude: vtkStaticCellLinksTemplate.h
