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

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

  Copyright (c) 1993-2002 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 vtkClipDataSet - clip any dataset with user-specified implicit function or input scalar data
// .SECTION Description
// vtkClipDataSet is a filter that any type of dataset 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, which pulls out
// entire, uncut cells.) The output of this filter is an unstructured
// grid.
//
// 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:
// 1) define an implicit function
// 2) set it with the SetClipFunction method
// 3) apply the GenerateClipScalarsOn method
// If a ClipFunction is not specified, or GenerateClipScalars is off
// (the default), then the input's scalar data will be used to clip
// the polydata.
//
// 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 clipping 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 part of the cell that is clipped away. Set the
// GenerateClippedData boolean on if you wish to access this output data.

// .SECTION Caveats
// vtkClipDataSet will triangulate all types of 3D cells (i.e., create
// tetrahedra). This is true even if the cell is not actually cut. This
// is necessary to preserve compatibility across face neighbors. 2D cells
// will only be triangulated if the cutting function passes through them.

// .SECTION See Also
// vtkImplicitFunction vtkCutter vtkClipVolume vtkClipPolyData

#ifndef __vtkClipDataSet_h
#define __vtkClipDataSet_h

#include "vtkDataSetToUnstructuredGridFilter.h"
#include "vtkImplicitFunction.h"

class vtkPointLocator;

class VTK_GRAPHICS_EXPORT vtkClipDataSet : public vtkDataSetToUnstructuredGridFilter
{
public:
  vtkTypeRevisionMacro(vtkClipDataSet,vtkDataSetToUnstructuredGridFilter);
  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.
  static vtkClipDataSet *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 selected 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 polygonal data that's been clipped away.
  vtkSetMacro(GenerateClippedOutput,int);
  vtkGetMacro(GenerateClippedOutput,int);
  vtkBooleanMacro(GenerateClippedOutput,int);

  // Description:
  // Set the tolerance for merging clip intersection points that are near
  // the vertices of cells. This tolerance is used to prevent the generation
  // of degenerate primitives. Note that only 3D cells actually use this
  // instance variable.
  vtkSetClampMacro(MergeTolerance,float,0.0001,0.25);
  vtkGetMacro(MergeTolerance,float);
  
  // Description:
  // Return the Clipped output.
  vtkUnstructuredGrid *GetClippedOutput();

  // Description:
  // Specify 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 GetMTime();

  // Description:
  // If you want to clip by an arbitrary array, then set its name here.
  // By default this in NULL and the filter will use the active scalar array.
  vtkGetStringMacro(InputScalarsSelection);
  void SelectInputScalars(const char *fieldName) 
    {this->SetInputScalarsSelection(fieldName);}

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

  void Execute();
  vtkImplicitFunction *ClipFunction;
  
  vtkPointLocator *Locator;
  int InsideOut;
  float Value;
  int GenerateClipScalars;

  int GenerateClippedOutput;
  float MergeTolerance;

  char *InputScalarsSelection;
  vtkSetStringMacro(InputScalarsSelection);

  //helper functions
  void ClipVolume();

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

#endif
