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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkImplicitVolume.h,v $
  Language:  C++
  Date:      $Date: 2001/10/11 13:36:35 $
  Version:   $Revision: 1.29 $


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

 * Modified source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/
// .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
// The input volume data is only updated when GetMTime() is called.
// 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 "vtkImageData.h"

class VTK_FILTERING_EXPORT vtkImplicitVolume : public vtkImplicitFunction
{
public:
  vtkTypeMacro(vtkImplicitVolume,vtkImplicitFunction);
  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();

  // Description:
  // Returns the mtime also considering the volume.  This also calls Update
  // on the volume, and it therefore must be called before the function is
  // evaluated.
  unsigned long GetMTime();

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

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

  // 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:
  vtkImplicitVolume();
  ~vtkImplicitVolume();

  vtkImageData *Volume; // the structured points
  float OutValue;
  float OutGradient[3];
  // to replace a static
  vtkIdList *PointIds;
private:
  vtkImplicitVolume(const vtkImplicitVolume&);  // Not implemented.
  void operator=(const vtkImplicitVolume&);  // Not implemented.
};

#endif