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/*=========================================================================
Program: Visualization Toolkit
Module: TestSPHKernels.cxx
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.
=========================================================================*/
// Perform unit tests on SPH kernels. This means:
// + integrating the kernels in 2D and 3D to ensure that the "volume"
// contained in the kernel sums to 1.0 (within epsilon)
// + ensuring that the kernel function is symmetric
// + ensuring that the kernel derivative takes on the correct sign
// and value on either side of the central point.
#include "vtkSmartPointer.h"
#include "vtkSPHCubicKernel.h"
#include "vtkSPHQuarticKernel.h"
#include "vtkSPHQuinticKernel.h"
#include "vtkWendlandQuinticKernel.h"
#include "vtkMath.h"
#include "vtkMathUtilities.h"
#include <string>
#include <cmath>
#include <sstream>
//-----------------------------------------------------------------------------
// Helper function
template <class T>
int TestSPHKernel(vtkSmartPointer<T> kernel, const std::string &description)
{
int status = EXIT_SUCCESS;
double res = 100;
double smoothingLen = 1.0;
double area, volume;
int i, j, k;
double x, y, z, r;
double cutoff, inc, normFactor;
double integral;
// Test 2D
kernel->SetDimension(2);
kernel->SetSpatialStep(smoothingLen);
kernel->Initialize(NULL,NULL,NULL);
normFactor = kernel->GetNormFactor();
cutoff = kernel->GetCutoffFactor();
inc = 2.0*cutoff / static_cast<double>(res);
area = inc * inc;
integral = 0.0;
for (j=0; j < res; ++j)
{
y = -cutoff + j*inc;
for (i=0; i < res; ++i)
{
x = -cutoff + i*inc;
r = sqrt( x*x + y*y );
integral += area * normFactor * kernel->ComputeFunctionWeight(r);
}
}
std::cout << "SPH " << description << " Kernel Integral (2D): " << integral << std::endl;
if ( integral < 0.99 || integral > 1.01 )
{
status = EXIT_FAILURE;
}
// Test 3D
kernel->SetDimension(3);
kernel->SetSpatialStep(smoothingLen);
kernel->Initialize(NULL,NULL,NULL);
normFactor = kernel->GetNormFactor();
cutoff = kernel->GetCutoffFactor();
inc = 2.0*cutoff / static_cast<double>(res);
volume = inc * inc * inc;
integral = 0.0;
for (k=0; k < res; ++k)
{
z = -cutoff + k*inc;
for (j=0; j < res; ++j)
{
y = -cutoff + j*inc;
for (i=0; i < res; ++i)
{
x = -cutoff + i*inc;
r = sqrt( x*x + y*y + z*z );
integral += volume * normFactor * kernel->ComputeFunctionWeight(r);
}
}
}
std::cout << "SPH " << description << " Kernel Integral (3D): " << integral << std::endl;
if ( integral < 0.99 || integral > 1.01 )
{
status = EXIT_FAILURE;
}
return status;
}
//-----------------------------------------------------------------------------
int TestSPHKernels(int, char*[])
{
int status = EXIT_SUCCESS;
// We will integrate over the kernel starting at a point beyond the cutoff
// distance (since these should make zero contribution to the
// integral). Note the integration occurs over a 2D or 3D domain
// Cubic SPH Kernel
vtkSmartPointer<vtkSPHCubicKernel> cubic =
vtkSmartPointer<vtkSPHCubicKernel>::New();
status += TestSPHKernel<vtkSPHCubicKernel>(cubic, "Cubic");
// Quartic Kernel
vtkSmartPointer<vtkSPHQuarticKernel> quartic =
vtkSmartPointer<vtkSPHQuarticKernel>::New();
status += TestSPHKernel<vtkSPHQuarticKernel>(quartic, "Quartic");
// Quintic Kernel
vtkSmartPointer<vtkSPHQuinticKernel> quintic =
vtkSmartPointer<vtkSPHQuinticKernel>::New();
status += TestSPHKernel<vtkSPHQuinticKernel>(quintic, "Quintic");
// Wendland C2 (quintic) Kernel
vtkSmartPointer<vtkWendlandQuinticKernel> wendland =
vtkSmartPointer<vtkWendlandQuinticKernel>::New();
status += TestSPHKernel<vtkWendlandQuinticKernel>(wendland, "Wendland Quintic");
// Get out
if (status == EXIT_SUCCESS)
{
std::cout << " PASSED" << std::endl;
}
else
{
std::cout << " FAILED" << std::endl;
}
return status;
}
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