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

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


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
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=========================================================================*/
// .NAME vtkClipVolume - clip volume data with user-specified implicit function or input scalar data
// .SECTION Description
// vtkClipVolume is a filter that clips volume data (i.e., structured points)
// using either: any subclass of vtkImplicitFunction; or the input scalar
// data. Clipping means that it actually "cuts" through the cells of the
// dataset, returning everything inside of the specified implicit function (or
// greater than the scalar value) including "pieces" of a cell. (Compare this
// with vtkExtractGeometry or vtkGeometryFilter, which pulls out entire,
// uncut cells.) The output of this filter is a 3D unstructured grid (e.g.,
// tetrahedra).
//
// To use this filter, you must decide if you will be clipping with an
// implicit function, or whether you will be using the input scalar data.  If
// you want to clip with an implicit function, you must first define and then
// set the implicit function with the SetClipFunction() method. Otherwise,
// you must make sure input scalar data is available. You can also specify a
// scalar value, which is used to decide what is inside and outside of the
// implicit function. You can also reverse the sense of what inside/outside
// is by setting the InsideOut instance variable. (The cutting algorithm
// proceeds by computing an implicit function value or using the input scalar
// data for each point in the dataset. This is compared to the scalar value
// to determine inside/outside.)
//
// This filter can be configured to compute a second output. The
// second output is the portion of the volume that is clipped away. Set the
// GenerateClippedData boolean on if you wish to access this output data.

// .SECTION Caveats
// This filter is designed to function with 3D structured points. Clipping
// 2D images can be better done by converting the image to polygonal data
// and using vtkClipPolyData,

// .SECTION See Also
// vtkImplicitFunction vtkClipPolyData vtkGeometryFilter vtkExtractGeometry

#ifndef __vtkClipVolume_h
#define __vtkClipVolume_h

#include "vtkStructuredPointsToUnstructuredGridFilter.h"
#include "vtkImplicitFunction.h"

class vtkMergePoints;
class vtkOrderedTriangulator;

class VTK_GRAPHICS_EXPORT vtkClipVolume : public vtkStructuredPointsToUnstructuredGridFilter
{
public:
  vtkTypeMacro(vtkClipVolume,vtkStructuredPointsToUnstructuredGridFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Construct with user-specified implicit function; InsideOut turned off;
  // value set to 0.0; and generate clip scalars turned off. The merge
  // tolerance is set to 0.01.
  static vtkClipVolume *New();

  // Description:
  // Set the clipping value of the implicit function (if clipping with
  // implicit function) or scalar value (if clipping with scalars). The
  // default value is 0.0.
  vtkSetMacro(Value,float);
  vtkGetMacro(Value,float);
  
  // Description:
  // Set/Get the InsideOut flag. When off, a vertex is considered inside the
  // implicit function if its value is greater than the Value ivar. When
  // InsideOutside is turned on, a vertex is considered inside the implicit
  // function if its implicit function value is less than or equal to the
  // Value ivar.  InsideOut is off by default.
  vtkSetMacro(InsideOut,int);
  vtkGetMacro(InsideOut,int);
  vtkBooleanMacro(InsideOut,int);

  // Description
  // Specify the implicit function with which to perform the clipping. If you
  // do not define an implicit function, then the input scalar data will be
  // used for clipping.
  vtkSetObjectMacro(ClipFunction,vtkImplicitFunction);
  vtkGetObjectMacro(ClipFunction,vtkImplicitFunction);

  // Description:
  // If this flag is enabled, then the output scalar values will be 
  // interpolated from the implicit function values, and not the 
  // input scalar data. If you enable this flag but do not provide an
  // implicit function an error will be reported.
  vtkSetMacro(GenerateClipScalars,int);
  vtkGetMacro(GenerateClipScalars,int);
  vtkBooleanMacro(GenerateClipScalars,int);

  // Description:
  // Control whether a second output is generated. The second output
  // contains the unstructured grid that's been clipped away.
  vtkSetMacro(GenerateClippedOutput,int);
  vtkGetMacro(GenerateClippedOutput,int);
  vtkBooleanMacro(GenerateClippedOutput,int);

  // Description:
  // Return the clipped output.
  vtkUnstructuredGrid *GetClippedOutput();

  // Description:
  // Set the tolerance for merging clip intersection points that are near
  // the corners of voxels. This tolerance is used to prevent the generation
  // of degenerate tetrahedra.
  vtkSetClampMacro(MergeTolerance,float,0.0001,0.25);
  vtkGetMacro(MergeTolerance,float);
  
  // Description:
  // Set / Get a spatial locator for merging points. By default, 
  // an instance of vtkMergePoints is used.
  void SetLocator(vtkPointLocator *locator);
  vtkGetObjectMacro(Locator,vtkPointLocator);

  // Description:
  // Create default locator. Used to create one when none is specified. The 
  // locator is used to merge coincident points.
  void CreateDefaultLocator();

  // Description:
  // Return the mtime also considering the locator and clip function.
  unsigned long int GetMTime();

protected:
  vtkClipVolume(vtkImplicitFunction *cf=NULL);
  ~vtkClipVolume();

  void Execute();
  void ClipVoxel(float value, vtkDataArray *cellScalars, int flip,
                 float origin[3], float spacing[3], vtkIdList *cellIds,
                 vtkPoints *cellPts, vtkPointData *inPD, vtkPointData *outPD,
                 vtkCellData *inCD, vtkIdType cellId, vtkCellData *outCD, 
                 vtkCellData *clippedCD);
  vtkImplicitFunction *ClipFunction;
  vtkPointLocator *Locator;
  int InsideOut;
  float Value;
  int GenerateClipScalars;
  float MergeTolerance;

  int GenerateClippedOutput;
  vtkUnstructuredGrid *ClippedOutput;
  
private:
  vtkUnstructuredGrid    *Mesh;
  vtkOrderedTriangulator *Triangulator;
  
private:
  vtkClipVolume(const vtkClipVolume&);  // Not implemented.
  void operator=(const vtkClipVolume&);  // Not implemented.
};

#endif
