1 /*=========================================================================
2 
3   Program:   Visualization Toolkit
4   Module:    vtkSPHCubicKernel.h
5 
6   Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
7   All rights reserved.
8   See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
9 
10      This software is distributed WITHOUT ANY WARRANTY; without even
11      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
12      PURPOSE.  See the above copyright notice for more information.
13 
14 =========================================================================*/
15 /**
16  * @class   vtkSPHCubicKernel
17  * @brief   a cubic SPH interpolation kernel
18  *
19  *
20  * vtkSPHCubicKernel is an smooth particle hydrodynamics interpolation kernel as
21  * described by D.J. Price. This is a cubic formulation.
22  *
23  * @warning
24  * For more information see D.J. Price, Smoothed particle hydrodynamics and
25  * magnetohydrodynamics, J. Comput. Phys. 231:759-794, 2012. Especially
26  * equation 49.
27  *
28  * @par Acknowledgments:
29  * The following work has been generously supported by Altair Engineering
30  * and FluiDyna GmbH. Please contact Steve Cosgrove or Milos Stanic for
31  * more information.
32  *
33  * @sa
34  * vtkSPHKernel vtkSPHInterpolator
35 */
36 
37 #ifndef vtkSPHCubicKernel_h
38 #define vtkSPHCubicKernel_h
39 
40 #include "vtkFiltersPointsModule.h" // For export macro
41 #include "vtkSPHKernel.h"
42 #include <algorithm> // For std::min()
43 
44 class vtkIdList;
45 class vtkDoubleArray;
46 
47 
48 class VTKFILTERSPOINTS_EXPORT vtkSPHCubicKernel : public vtkSPHKernel
49 {
50 public:
51   //@{
52   /**
53    * Standard methods for instantiation, obtaining type information, and printing.
54    */
55   static vtkSPHCubicKernel *New();
56   vtkTypeMacro(vtkSPHCubicKernel,vtkSPHKernel);
57   void PrintSelf(ostream& os, vtkIndent indent) override;
58   //@}
59 
60   /**
61    * Produce the computational parameters for the kernel. Invoke this method
62    * after setting initial values like SpatialStep.
63    */
64   void Initialize(vtkAbstractPointLocator *loc, vtkDataSet *ds,
65                           vtkPointData *pd) override;
66 
67   //@{
68   /**
69    * Compute weighting factor given a normalized distance from a sample point.
70    */
ComputeFunctionWeight(const double d)71   double ComputeFunctionWeight(const double d) override
72   {
73     double tmp1 = 2.0 - std::min(d,2.0);
74     double tmp2 = 1.0 - std::min(d,1.0);
75     return (0.25*tmp1*tmp1*tmp1 - tmp2*tmp2*tmp2);
76   }
77   //@}
78 
79   //@{
80   /**
81    * Compute weighting factor for derivative quantities given a normalized
82    * distance from a sample point.
83    */
ComputeDerivWeight(const double d)84   double ComputeDerivWeight(const double d) override
85   {
86     double tmp1 = 2.0 - std::min(d,2.0);
87     double tmp2 = 1.0 - std::min(d,1.0);
88     return (-0.75*tmp1*tmp1 + 3.0*tmp2*tmp2);
89   }
90   //@}
91 
92 protected:
93   vtkSPHCubicKernel();
94   ~vtkSPHCubicKernel() override;
95 
96 private:
97   vtkSPHCubicKernel(const vtkSPHCubicKernel&) = delete;
98   void operator=(const vtkSPHCubicKernel&) = delete;
99 };
100 
101 #endif
102