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

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


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
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=========================================================================*/
// .NAME vtkImplicitDataSet - treat a dataset as if it were an implicit function
// .SECTION Description
// vtkImplicitDataSet treats any type of dataset as if it were an
// implicit function. This means it computes a function value and 
// gradient. vtkImplicitDataSet is a concrete implementation of 
// vtkImplicitFunction.
//
// vtkImplicitDataSet computes the function (at the point x) by performing 
// cell interpolation. That is, it finds the cell containing x, and then
// uses the cell's interpolation functions to compute an interpolated
// scalar value at x. (A similar approach is used to find the
// gradient, if requested.) Points outside of the dataset are assigned 
// the value of the ivar OutValue, and the gradient value OutGradient.

// .SECTION Caveats
// Any type of dataset can be used as an implicit function as long as it
// has scalar data associated with it.

// .SECTION See Also
// vtkImplicitFunction vtkImplicitVolume vtkClipPolyData vtkCutter
// vtkImplicitWindowFunction

#ifndef __vtkImplicitDataSet_h
#define __vtkImplicitDataSet_h

#include "vtkImplicitFunction.h"
#include "vtkDataSet.h"

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

  // Description
  // Construct an vtkImplicitDataSet with no initial dataset; the OutValue
  // set to a large negative number; and the OutGradient set to (0,0,1).
  static vtkImplicitDataSet *New();

  // Description:
  // Return the MTime also considering the DataSet dependency.
  unsigned long GetMTime();

  // Description
  // Evaluate the implicit function. This returns the interpolated scalar value
  // at x[3].
  float EvaluateFunction(float x[3]);
  float EvaluateFunction(float x, float y, float z)
    {return this->vtkImplicitFunction::EvaluateFunction(x, y, z); } ;

  // Description
  // Evaluate implicit function gradient.
  void EvaluateGradient(float x[3], float n[3]);

  // Description:
  // Set / get the dataset used for the implicit function evaluation.
  vtkSetObjectMacro(DataSet,vtkDataSet);
  vtkGetObjectMacro(DataSet,vtkDataSet);

  // Description:
  // Set / get the function value to use for points outside of the dataset.
  vtkSetMacro(OutValue,float);
  vtkGetMacro(OutValue,float);

  // Description:
  // Set / get the function gradient to use for points outside of the dataset.
  vtkSetVector3Macro(OutGradient,float);
  vtkGetVector3Macro(OutGradient,float);

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

  vtkDataSet *DataSet;
  float OutValue;
  float OutGradient[3];

  float *Weights; //used to compute interpolation weights
  int Size; //keeps track of length of weights array

};

#endif


