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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkPiecewiseFunction.h"
#include "vtkNew.h"
#include <cmath>
#include <vector>
#define TEST_ASSERT_FUZZY_EQUAL(expect, actual) \
do \
{ \
if (std::fabs((expect) - (actual)) >= 1e-12) \
{ \
std::cerr << "Error at line " << __LINE__ << ": Expected value " << (expect) << ", got " \
<< (actual) << std::endl; \
return EXIT_FAILURE; \
} \
} while (false)
int BasicTestPiecewiseFunction()
{
vtkNew<vtkPiecewiseFunction> func;
func->AllowDuplicateScalarsOn();
// Add some points that will give easily predictable interpolations.
func->AddPoint(0., -2.);
func->AddPoint(50., 0.);
int ret = func->AddPoint(50., 2.);
if (ret != 2)
{
std::cerr << "Error adding duplicated point" << std::endl;
return EXIT_FAILURE;
}
func->AddPoint(100., 5.);
// Check that the interpolations are correct.
TEST_ASSERT_FUZZY_EQUAL(-1., func->GetValue(25.));
TEST_ASSERT_FUZZY_EQUAL(3.5, func->GetValue(75.));
// Check that point removing is working
func->RemovePoint(50., 2.);
TEST_ASSERT_FUZZY_EQUAL(2.5, func->GetValue(75.));
func->AddPoint(50., 2.);
func->RemovePoint(50.);
TEST_ASSERT_FUZZY_EQUAL(0., func->GetValue(25.));
return EXIT_SUCCESS;
}
//----------------------------------------------------------------------------
// Test the interpolation search method
int TestInterpolationSearchMethod()
{
// we will create two piecewise functions,
// one with a linear distributed sampling
// one with a non linear sampling
// number of points in the piecewise function
const int Ndata = 15000;
// number of interpolations asked to the piecewise function
const int N = 5 * Ndata;
std::vector<double> linearInterlacedData(2 * Ndata, 0);
std::vector<double> nonLinearInterlacedData(2 * Ndata, 0);
vtkNew<vtkPiecewiseFunction> lin;
vtkNew<vtkPiecewiseFunction> nonLin;
for (int i = 0; i < Ndata; i++)
{
double time = 1.0 + static_cast<double>(2 * i) / static_cast<double>(Ndata) * (3.0 - 1.0);
double value = std::exp(time);
// linearly distributed samples
linearInterlacedData[2 * i] = time;
linearInterlacedData[2 * i + 1] = value;
// non linearly distributed samples
nonLinearInterlacedData[2 * i] = 0.54 * time * time + 1.89 * time;
nonLinearInterlacedData[2 * i + 1] = value;
}
lin->FillFromDataPointer(Ndata, linearInterlacedData.data());
nonLin->FillFromDataPointer(Ndata, nonLinearInterlacedData.data());
// Test first if the update search method is pertinent
lin->UpdateSearchMethod();
nonLin->UpdateSearchMethod();
int method = lin->GetAutomaticSearchMethod();
if (method != static_cast<int>(vtkPiecewiseFunction::INTERPOLATION_SEARCH))
{
std::cerr << "Error at line " << __LINE__ << ": interpolation search method expected"
<< std::endl;
return EXIT_FAILURE;
}
method = nonLin->GetAutomaticSearchMethod();
if (method != static_cast<int>(vtkPiecewiseFunction::BINARY_SEARCH))
{
std::cerr << "Error at line " << __LINE__ << ": binary search method expected" << std::endl;
return EXIT_FAILURE;
}
// Then compare the two methods with linear and non linear samples
lin->SetUseCustomSearchMethod(true);
lin->SetCustomSearchMethod(vtkPiecewiseFunction::BINARY_SEARCH);
nonLin->SetUseCustomSearchMethod(true);
nonLin->SetCustomSearchMethod(vtkPiecewiseFunction::BINARY_SEARCH);
std::vector<double> linearTableBinary(N, 0);
std::vector<double> nonLinearTableBinary(N, 0);
std::vector<double> linearTableInterpolation(N, 0);
std::vector<double> nonLinearTableInterpolation(N, 0);
lin->GetTable(0, 8, N, linearTableBinary.data());
nonLin->GetTable(0, 8, N, nonLinearTableBinary.data());
lin->SetCustomSearchMethod(vtkPiecewiseFunction::INTERPOLATION_SEARCH);
nonLin->SetCustomSearchMethod(vtkPiecewiseFunction::INTERPOLATION_SEARCH);
lin->GetTable(0, 8, N, linearTableInterpolation.data());
nonLin->GetTable(0, 8, N, nonLinearTableInterpolation.data());
for (int k = 0; k < N; ++k)
{
TEST_ASSERT_FUZZY_EQUAL(linearTableBinary[k], linearTableInterpolation[k]);
TEST_ASSERT_FUZZY_EQUAL(nonLinearTableBinary[k], nonLinearTableInterpolation[k]);
}
return EXIT_SUCCESS;
}
//----------------------------------------------------------------------------
// Test if the interpolation is correct on a few data points
int TestGetTable()
{
// number of points in the piecewise function
const int Ndata = 6;
// number of interpolations asked to the piecewise function
const int N = 9;
// expected result
const double res[9] = { 2.718281828459, 2.718281828459, 3.684359911713, 5.133477036594,
7.803374275898, 10.923088402692, 16.42055751499, 23.654739499744, 34.362347229412 };
std::vector<double> interlacedData(2 * Ndata, 0);
std::vector<double> table(N, 0);
vtkNew<vtkPiecewiseFunction> f1;
for (int i = 0; i < Ndata; i++)
{
double time = 1.0 + static_cast<double>(2 * i) / Ndata * (3 - 1);
double value = std::exp(time);
interlacedData[2 * i] = time;
interlacedData[2 * i + 1] = value;
}
f1->FillFromDataPointer(Ndata, interlacedData.data());
f1->GetTable(0.5, 3.5, N, table.data());
for (int k = 0; k < N; ++k)
{
TEST_ASSERT_FUZZY_EQUAL(res[k], table[k]);
}
return EXIT_SUCCESS;
}
int TestPiecewiseFunction(int, char*[])
{
// Store up any errors, return non-zero if something fails.
int retVal = 0;
retVal += BasicTestPiecewiseFunction();
retVal += TestInterpolationSearchMethod();
retVal += TestGetTable();
return retVal;
}
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