VTK-5.0.0/Hybrid/vtkImplicitModeller.h

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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkImplicitModeller.h,v $

  Copyright (c) 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 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.  Do not switch between voxel and cell mode between execution
// of StartAppend and EndAppend.
//<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.
//<P>
// This filter can now produce output of any type supported by vtkImageData.  
// However to support this change, additional sqrts must be executed during the
// Append step.  Previously, the output was initialized to the squared CapValue 
// in StartAppend, the output was updated with squared distance values during 
// the Append, and then the sqrt of the distances was computed in EndAppend.  
// To support different scalar types in the output (largely to reduce memory 
// requirements as an vtkImageShiftScale and/or vtkImageCast could have 
// achieved the same result), we can't "afford" to save squared value in the
// output, because then we could only represent up to the sqrt of the scalar
// max for an integer type in the output; 1 (instead of 255) for an unsigned
// char; 11 for a char (instead of 127).  Thus this change may result in a
// minor performance degradation.  Non-float output types can be scaled to the
// CapValue by turning ScaleToMaximumDistance On.
//
// .SECTION See Also
// vtkSampleFunction vtkContourFilter

#ifndef __vtkImplicitModeller_h
#define __vtkImplicitModeller_h

#include "vtkImageAlgorithm.h"

#define VTK_VOXEL_MODE   0
#define VTK_CELL_MODE    1

class vtkDataArray;
class vtkExtractGeometry;
class vtkMultiThreader;

class VTK_HYBRID_EXPORT vtkImplicitModeller : public vtkImageAlgorithm 
{
public:
  vtkTypeRevisionMacro(vtkImplicitModeller,vtkImageAlgorithm);
  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.
  double 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,double,0.0,1.0);
  vtkGetMacro(MaximumDistance,double);

  // Description:
  // Set / get the region in space in which to perform the sampling. If
  // not specified, it will be computed automatically.
  vtkSetVector6Macro(ModelBounds,double);
  vtkGetVectorMacro(ModelBounds,double,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,double,-1.0,1.0);
  vtkGetMacro(AdjustDistance,double);

  // 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.
  void SetCapValue(double value);
  vtkGetMacro(CapValue,double);

  // Description:
  // If a non-floating output type is specified, the output distances can be
  // scaled to use the entire positive scalar range of the output type 
  // specified (up to the CapValue which is equal to the max for the type 
  // unless modified by the user).  For example, if ScaleToMaximumDistance
  // is On and the OutputScalarType is UnsignedChar the distances saved in the
  // output would be linearly scaled between 0 (for distances "very close" to
  // the surface) and 255 (at the specifed maximum distance)... assuming the 
  // CapValue is not changed from 255.
  vtkSetMacro(ScaleToMaximumDistance, int);
  vtkGetMacro(ScaleToMaximumDistance, int);
  vtkBooleanMacro(ScaleToMaximumDistance,int);

  // 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
  vtkSetClampMacro( NumberOfThreads, int, 1, VTK_MAX_THREADS );
  vtkGetMacro( NumberOfThreads, int );

  // Description:
  // Set the desired output scalar type.
  void SetOutputScalarType(int type);
  vtkGetMacro(OutputScalarType,int);
  void SetOutputScalarTypeToFloat(){this->SetOutputScalarType(VTK_FLOAT);};
  void SetOutputScalarTypeToDouble(){this->SetOutputScalarType(VTK_DOUBLE);};
  void SetOutputScalarTypeToInt(){this->SetOutputScalarType(VTK_INT);};
  void SetOutputScalarTypeToUnsignedInt()
    {this->SetOutputScalarType(VTK_UNSIGNED_INT);};
  void SetOutputScalarTypeToLong(){this->SetOutputScalarType(VTK_LONG);};
  void SetOutputScalarTypeToUnsignedLong()
    {this->SetOutputScalarType(VTK_UNSIGNED_LONG);};
  void SetOutputScalarTypeToShort(){this->SetOutputScalarType(VTK_SHORT);};
  void SetOutputScalarTypeToUnsignedShort()   
    {this->SetOutputScalarType(VTK_UNSIGNED_SHORT);};
  void SetOutputScalarTypeToUnsignedChar()
    {this->SetOutputScalarType(VTK_UNSIGNED_CHAR);};
  void SetOutputScalarTypeToChar()
    {this->SetOutputScalarType(VTK_CHAR);};

  // 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();

  // See the vtkAlgorithm for a desciption of what these do
  int ProcessRequest(vtkInformation*,
                     vtkInformationVector**,
                     vtkInformationVector*);

protected:
  vtkImplicitModeller();
  ~vtkImplicitModeller();

  double GetScalarTypeMax(int type);

  virtual int RequestInformation (vtkInformation *, 
                                  vtkInformationVector **,
                                  vtkInformationVector *);
  virtual int RequestData (vtkInformation *, 
                           vtkInformationVector **, vtkInformationVector *);
  
  void StartAppend(int internal);
  void Cap(vtkDataArray *s);

  vtkMultiThreader *Threader;
  int              NumberOfThreads;

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

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

  virtual int FillInputPortInformation(int, vtkInformation*);

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

#endif