vtkSPHKernel.h

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

  Program:   Visualization Toolkit
  Module:    vtkSPHKernel.h

  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.

=========================================================================*/
#ifndef vtkSPHKernel_h
#define vtkSPHKernel_h

#include "vtkFiltersPointsModule.h" // For export macro
#include "vtkInterpolationKernel.h"
#include "vtkStdString.h" // For vtkStdString ivars

class vtkIdList;
class vtkDoubleArray;
class vtkDataArray;
class vtkFloatArray;


class VTKFILTERSPOINTS_EXPORT vtkSPHKernel : public vtkInterpolationKernel
{
public:

  vtkTypeMacro(vtkSPHKernel,vtkInterpolationKernel);
  void PrintSelf(ostream& os, vtkIndent indent) override;


  vtkSetClampMacro(SpatialStep,double,0.0,VTK_FLOAT_MAX);
  vtkGetMacro(SpatialStep,double);


  vtkSetClampMacro(Dimension,int,1,3);
  vtkGetMacro(Dimension,int);


  vtkGetMacro(CutoffFactor,double);


  virtual void SetCutoffArray(vtkDataArray*);
  vtkGetObjectMacro(CutoffArray,vtkDataArray);


  virtual void SetDensityArray(vtkDataArray*);
  vtkGetObjectMacro(DensityArray,vtkDataArray);


  virtual void SetMassArray(vtkDataArray*);
  vtkGetObjectMacro(MassArray,vtkDataArray);

  void Initialize(vtkAbstractPointLocator *loc, vtkDataSet *ds,
                          vtkPointData *pd) override;

  vtkIdType ComputeBasis(double x[3], vtkIdList *pIds, vtkIdType ptId=0) override;

  vtkIdType ComputeWeights(double x[3], vtkIdList *pIds,
                                   vtkDoubleArray *weights) override;

  virtual vtkIdType ComputeDerivWeights(double x[3], vtkIdList *pIds,
                                        vtkDoubleArray *weights,
                                        vtkDoubleArray *gradWeights);

  virtual double ComputeFunctionWeight(const double d) = 0;

  virtual double ComputeDerivWeight(const double d) = 0;


  vtkGetMacro(NormFactor,double);

protected:
  vtkSPHKernel();
  ~vtkSPHKernel() override;

  // Instance variables
  double SpatialStep; //also known as smoothing length h
  int Dimension; //sptial dimension of the kernel

  // Optional arrays aid in the interpolation process (computes volume)
  vtkDataArray *CutoffArray;
  vtkDataArray *DensityArray;
  vtkDataArray *MassArray;

  // Internal data members generated during construction and initialization
  // Terminology is spatial step = smoothing length h
  double CutoffFactor; //varies across each kernel, e.g. cubic=2, quartic=2.5, quintic=3
  double Cutoff; //the spatial step * cutoff factor
  double Sigma; //normalization constant
  double DistNorm; //distance normalization factor 1/(spatial step)
  double NormFactor; //dimensional normalization factor sigma/(spatial step)^Dimension
  double DefaultVolume; //if mass and density arrays not specified, use this
  bool UseCutoffArray; //if single component cutoff array provided
  bool UseArraysForVolume; //if both mass and density arrays are present

private:
  vtkSPHKernel(const vtkSPHKernel&) = delete;
  void operator=(const vtkSPHKernel&) = delete;
};

#endif