1 /*=========================================================================
2 
3   Program:   Visualization Toolkit
4   Module:    vtkWendlandQuinticKernel.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   vtkWendlandQuinticKernel
17  * @brief   a quintic SPH interpolation kernel
18  *
19  *
20  * vtkWendlandQuinticKernel is an smooth particle hydrodynamics interpolation kernel as
21  * described by D.J. Price. This is a quintic 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 vtkWendlandQuinticKernel_h
38 #define vtkWendlandQuinticKernel_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 vtkWendlandQuinticKernel : public vtkSPHKernel
49 {
50 public:
51   //@{
52   /**
53    * Standard methods for instantiation, obtaining type information, and printing.
54    */
55   static vtkWendlandQuinticKernel *New();
56   vtkTypeMacro(vtkWendlandQuinticKernel,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    * Note that the formulation is slightly different to avoid an extra operation
71    * (which has the effect of affecting the NormFactor by 1/16).
72    */
ComputeFunctionWeight(const double d)73   double ComputeFunctionWeight(const double d) override
74   {
75     if ( d >= 2.0 )
76     {
77       return 0.0;
78     }
79     else
80     {
81       double tmp = 1.0 - 0.5*d;
82       return (tmp*tmp*tmp*tmp) * (1.0 + 2.0*d);
83     }
84   }
85   //@}
86 
87   //@{
88   /**
89    * Compute weighting factor for derivative quantities given a normalized
90    * distance from a sample point.
91    */
ComputeDerivWeight(const double d)92   double ComputeDerivWeight(const double d) override
93   {
94     if ( d >= 2.0 )
95     {
96       return 0.0;
97     }
98     else
99     {
100       double tmp = 1.0 - 0.5*d;
101       return -2.0*(tmp*tmp*tmp) * (1.0 + 2.0*d) +
102         2.0*(tmp*tmp*tmp*tmp);
103     }
104   }
105   //@}
106 
107 protected:
108   vtkWendlandQuinticKernel();
109   ~vtkWendlandQuinticKernel() override;
110 
111 private:
112   vtkWendlandQuinticKernel(const vtkWendlandQuinticKernel&) = delete;
113   void operator=(const vtkWendlandQuinticKernel&) = delete;
114 };
115 
116 #endif
117