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

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


Copyright (c) 1993-1998 Ken Martin, Will Schroeder, Bill Lorensen.

This software is copyrighted by Ken Martin, Will Schroeder and Bill Lorensen.
The following terms apply to all files associated with the software unless
explicitly disclaimed in individual files. This copyright specifically does
not apply to the related textbook "The Visualization Toolkit" ISBN
013199837-4 published by Prentice Hall which is covered by its own copyright.

The authors hereby grant permission to use, copy, and distribute this
software and its documentation for any purpose, provided that existing
copyright notices are retained in all copies and that this notice is included
verbatim in any distributions. Additionally, the authors grant permission to
modify this software and its documentation for any purpose, provided that
such modifications are not distributed without the explicit consent of the
authors and that existing copyright notices are retained in all copies. Some
of the algorithms implemented by this software are patented, observe all
applicable patent law.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
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=========================================================================*/
// .NAME vtkImplicitVolume - treat a volume as if it were an implicit function
// .SECTION Description
// vtkImplicitVolume treats a volume (e.g., structured point dataset)
// as if it were an implicit function. This means it computes a function
// value and gradient. vtkImplicitVolume 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
// Works for 3D structured points datasets, 0D-2D datasets won't work properly.

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

#ifndef __vtkImplicitVolume_h
#define __vtkImplicitVolume_h

#include "vtkImplicitFunction.h"
#include "vtkStructuredPoints.h"

class VTK_EXPORT vtkImplicitVolume : public vtkImplicitFunction
{
public:
  vtkImplicitVolume();
  ~vtkImplicitVolume();
  const char *GetClassName() {return "vtkImplicitVolume";}
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description
  // Construct an vtkImplicitVolume with no initial volume; the OutValue
  // set to a large negative number; and the OutGradient set to (0,0,1).
  static vtkImplicitVolume *New() {return new vtkImplicitVolume;}

  // Description:
  // Returns the mtime also considering the volume.
  unsigned long GetMTime();

  // Description
  // Evaluate the ImplicitVolume. This returns the interpolated scalar value
  // at x[3].
  float EvaluateFunction(float x[3]);

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

  // Description:
  // Specify the volume for the implicit function.
  vtkSetObjectMacro(Volume,vtkStructuredPoints);
  vtkGetObjectMacro(Volume,vtkStructuredPoints);

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

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

protected:
  vtkStructuredPoints *Volume; // the structured points
  float OutValue;
  float OutGradient[3];
  // to replace a static
  vtkIdList *PointIds;
};

#endif


