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

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


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
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=========================================================================*/
// .NAME vtkImplicitModeller - compute distance from input geometry on structured point dataset
// .SECTION Description
// vtkImplicitModeller is a filter that computes the distance from the input
// geometry to the points of an output structured point set. This distance
// function can then be "contoured" to generate new, offset surfaces from
// the original geometry. An important feature of this object is
// "capping". If capping is turned on, after the implicit model is created,
// the values on the boundary of the structured points dataset are set to
// the cap value. This is used to force closure of the resulting contoured
// surface. Note, however, that large cap values can generate weird surface
// normals in those cells adjacent to the boundary of the dataset. Using
// smaller cap value will reduce this effect.
//<P>
// Another important ivar is MaximumDistance. This controls how far into the
// volume the distance function is computed from the input geometry.  Small
// values give significant increases in performance. However, there can
// strange sampling effects at the extreme range of the MaximumDistance.
//<P>
// In order to properly execute and sample the input data, a rectangular
// region in space must be defined (this is the ivar ModelBounds).  If not
// explicitly defined, the model bounds will be computed. Note that to avoid
// boundary effects, it is possible to adjust the model bounds (i.e., using
// the AdjustBounds and AdjustDistance ivars) to strictly contain the
// sampled data.
//<P>
// This filter has one other unusual capability: it is possible to append
// data in a sequence of operations to generate a single output. This is
// useful when you have multiple datasets and want to create a
// conglomeration of all the data.  However, the user must be careful to
// either specify the ModelBounds or specify the first item such that its
// bounds completely contain all other items.  This is because the 
// rectangular region of the output can not be changed after the 1st Append.
//<P>
// The ProcessMode ivar controls the method used within the Append function
// (where the actual work is done regardless if the Append function is
// explicitly called) to compute the implicit model.  If set to work in voxel
// mode, each voxel is visited once.  If set to cell mode, each cell is visited
// once.  Tests have shown once per voxel to be faster when there are a 
// lot of cells (at least a thousand?); relative performance improvement 
// increases with addition cells. Primitives should not be stripped for best
// performance of the voxel mode.  Also, if explicitly using the Append feature
// many times, the cell mode will probably be better because each voxel will be
// visited each Append.  Append the data before input if possible when using
// the voxel mode.
//<P>
// Further performance improvement is now possible using the PerVoxel process
// mode on multi-processor machines (the mode is now multithreaded).  Each
// thread processes a different "slab" of the output.  Also, if the input is 
// vtkPolyData, it is appropriately clipped for each thread; that is, each 
// thread only considers the input which could affect its slab of the output.

// .SECTION See Also
// vtkSampleFunction vtkContourFilter

#ifndef __vtkImplicitModeller_h
#define __vtkImplicitModeller_h

#include "vtkDataSetToStructuredPointsFilter.h"

#define VTK_VOXEL_MODE   0
#define VTK_CELL_MODE    1

class vtkMultiThreader;
class vtkExtractGeometry;

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

  // Description:
  // Construct with sample dimensions=(50,50,50), and so that model bounds are
  // automatically computed from the input. Capping is turned on with CapValue
  // equal to a large positive number.
  static vtkImplicitModeller *New();

  // Description:
  // Compute ModelBounds from input geometry. If input is not specified, the input
  // of the filter will be used.
  float ComputeModelBounds(vtkDataSet *input = NULL);

  // Description:
  // Set/Get the i-j-k dimensions on which to sample distance function.
  vtkGetVectorMacro(SampleDimensions,int,3);
  void SetSampleDimensions(int i, int j, int k);
  void SetSampleDimensions(int dim[3]);

  // Description:
  // Set / get the distance away from surface of input geometry to
  // sample. Smaller values make large increases in performance.
  vtkSetClampMacro(MaximumDistance,float,0.0,1.0);
  vtkGetMacro(MaximumDistance,float);

  // Description:
  // Set / get the region in space in which to perform the sampling. If
  // not specified, it will be computed automatically.
  vtkSetVector6Macro(ModelBounds,float);
  vtkGetVectorMacro(ModelBounds,float,6);

  // Description:
  // Control how the model bounds are computed. If the ivar AdjustBounds
  // is set, then the bounds specified (or computed automatically) is modified
  // by the fraction given by AdjustDistance. This means that the model
  // bounds is expanded in each of the x-y-z directions.
  vtkSetMacro(AdjustBounds,int);
  vtkGetMacro(AdjustBounds,int);
  vtkBooleanMacro(AdjustBounds,int);
  
  // Description:
  // Specify the amount to grow the model bounds (if the ivar AdjustBounds
  // is set). The value is a fraction of the maximum length of the sides
  // of the box specified by the model bounds.
  vtkSetClampMacro(AdjustDistance,float,-1.0,1.0);
  vtkGetMacro(AdjustDistance,float);

  // Description:
  // The outer boundary of the structured point set can be assigned a 
  // particular value. This can be used to close or "cap" all surfaces.
  vtkSetMacro(Capping,int);
  vtkGetMacro(Capping,int);
  vtkBooleanMacro(Capping,int);
  
  // Description:
  // Specify the capping value to use. The CapValue is also used as an
  // initial distance value at each point in the dataset.
  vtkSetMacro(CapValue,float);
  vtkGetMacro(CapValue,float);

  // Description:
  // Specify whether to visit each cell once per append or each voxel once
  // per append.  Some tests have shown once per voxel to be faster
  // when there are a lot of cells (at least a thousand?); relative
  // performance improvement increases with addition cells.  Primitives
  // should not be stripped for best performance of the voxel mode.
  vtkSetClampMacro(ProcessMode, int, 0, 1);
  vtkGetMacro(ProcessMode, int);
  void SetProcessModeToPerVoxel() {this->SetProcessMode(VTK_VOXEL_MODE);}
  void SetProcessModeToPerCell()  {this->SetProcessMode(VTK_CELL_MODE);}
  const char *GetProcessModeAsString(void);

  // Description:
  // Specify the level of the locator to use when using the per voxel
  // process mode.
  vtkSetMacro(LocatorMaxLevel,int);
  vtkGetMacro(LocatorMaxLevel,int);

  // Description:
  // Set / Get the number of threads used during Per-Voxel processing mode
  vtkSetMacro( NumberOfThreads, int );
  vtkGetMacro( NumberOfThreads, int );

  // Description:
  // Initialize the filter for appending data. You must invoke the
  // StartAppend() method before doing successive Appends(). It's also a
  // good idea to manually specify the model bounds; otherwise the input
  // bounds for the data will be used.
  void StartAppend();

  // Description:
  // Append a data set to the existing output. To use this function,
  // you'll have to invoke the StartAppend() method before doing
  // successive appends. It's also a good idea to specify the model
  // bounds; otherwise the input model bounds is used. When you've
  // finished appending, use the EndAppend() method.
  void Append(vtkDataSet *input);

  // Description:
  // Method completes the append process.
  void EndAppend();

  // Description:
  virtual void UpdateData(vtkDataObject *output);

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

  void Execute();
  void ExecuteInformation();
  
  void Cap(vtkScalars *s);

  vtkMultiThreader *Threader;
  int              NumberOfThreads;

  int SampleDimensions[3];
  float MaximumDistance;
  float ModelBounds[6];
  int Capping;
  float CapValue;
  int DataAppended;
  int AdjustBounds;
  float AdjustDistance;
  int ProcessMode;
  int LocatorMaxLevel;

  int BoundsComputed; // flag to limit to one ComputeModelBounds per StartAppend
  float InternalMaxDistance; // the max distance computed during that one call
};

#endif


