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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
// .NAME
// .SECTION Description
// This tests the code used in Documentation/Doxygen/SMPTools.md.
#include "vtkFloatArray.h"
#include "vtkMath.h"
#include "vtkMultiThreader.h"
#include "vtkNew.h"
#include "vtkPoints.h"
#include "vtkSMPThreadLocal.h"
#include "vtkSMPTools.h"
#include <array>
#include <vector>
namespace
{
// Compute a bounding hull with the planes provided.
struct HullFunctor
{
vtkPoints* InPts;
std::vector<double>& Planes;
HullFunctor(vtkPoints* inPts, std::vector<double>& planes)
: InPts(inPts)
, Planes(planes)
{
}
void operator()(vtkIdType ptId, vtkIdType endPtId)
{
vtkPoints* inPts = this->InPts;
std::vector<double>& planes = this->Planes;
auto numPlanes = planes.size() / 4;
for (; ptId < endPtId; ++ptId)
{
double v, coord[3];
inPts->GetPoint(ptId, coord);
for (size_t j = 0; j < numPlanes; j++)
{
v = -(planes[j * 4 + 0] * coord[0] + planes[j * 4 + 1] * coord[1] +
planes[j * 4 + 2] * coord[2]);
// negative means further in + direction of plane
if (v < planes[j * 4 + 3])
{
planes[j * 4 + 3] = v;
}
}
}
}
}; // HullFunctor
using BoundsArray = std::array<double, 6>;
using TLS = vtkSMPThreadLocal<BoundsArray>;
// Compute bounds of a set of points.
struct BoundsFunctor
{
vtkFloatArray* Pts;
BoundsArray Bounds;
TLS LocalBounds;
BoundsFunctor(vtkFloatArray* pts)
: Pts(pts)
{
}
// Initialize thread local storage
void Initialize()
{
// The first call to .Local() will create the array,
// all others will return the same.
std::array<double, 6>& bds = this->LocalBounds.Local();
bds[0] = VTK_DOUBLE_MAX;
bds[1] = -VTK_DOUBLE_MAX;
bds[2] = VTK_DOUBLE_MAX;
bds[3] = -VTK_DOUBLE_MAX;
bds[4] = VTK_DOUBLE_MAX;
bds[5] = -VTK_DOUBLE_MAX;
}
// Process the range of points [begin,end)
void operator()(vtkIdType begin, vtkIdType end)
{
BoundsArray& lbounds = this->LocalBounds.Local();
float* x = this->Pts->GetPointer(3 * begin);
for (vtkIdType i = begin; i < end; i++)
{
lbounds[0] = (x[0] < lbounds[0] ? x[0] : lbounds[0]);
lbounds[1] = (x[0] > lbounds[1] ? x[0] : lbounds[1]);
lbounds[2] = (x[1] < lbounds[2] ? x[1] : lbounds[2]);
lbounds[3] = (x[1] > lbounds[3] ? x[1] : lbounds[3]);
lbounds[4] = (x[2] < lbounds[4] ? x[2] : lbounds[4]);
lbounds[5] = (x[2] > lbounds[5] ? x[2] : lbounds[5]);
x += 3;
}
}
// Composite / combine the thread local storage into a global result.
void Reduce()
{
this->Bounds[0] = VTK_DOUBLE_MAX;
this->Bounds[1] = -VTK_DOUBLE_MAX;
this->Bounds[2] = VTK_DOUBLE_MAX;
this->Bounds[3] = -VTK_DOUBLE_MAX;
this->Bounds[4] = VTK_DOUBLE_MAX;
this->Bounds[5] = -VTK_DOUBLE_MAX;
using TLSIter = TLS::iterator;
TLSIter end = this->LocalBounds.end();
for (TLSIter itr = this->LocalBounds.begin(); itr != end; ++itr)
{
BoundsArray& lBounds = *itr;
this->Bounds[0] = (this->Bounds[0] < lBounds[0] ? this->Bounds[0] : lBounds[0]);
this->Bounds[1] = (this->Bounds[1] > lBounds[1] ? this->Bounds[1] : lBounds[1]);
this->Bounds[2] = (this->Bounds[2] < lBounds[2] ? this->Bounds[2] : lBounds[2]);
this->Bounds[3] = (this->Bounds[3] > lBounds[3] ? this->Bounds[3] : lBounds[3]);
this->Bounds[4] = (this->Bounds[4] < lBounds[4] ? this->Bounds[4] : lBounds[4]);
this->Bounds[5] = (this->Bounds[5] > lBounds[5] ? this->Bounds[5] : lBounds[5]);
}
}
}; // BoundsFunctor
// Support for the atomic example.
std::atomic<vtkTypeInt32> TotalAtomic(0);
constexpr int Target = 1000000;
constexpr int NumThreads = 2;
VTK_THREAD_RETURN_TYPE MyFunction(void*)
{
for (int i = 0; i < Target / NumThreads; i++)
{
++TotalAtomic;
}
return VTK_THREAD_RETURN_VALUE;
}
} // anonymous namespace
int TestSMPFeatures(int, char*[])
{
// Create a random set of points
constexpr vtkIdType numPts = 1000;
constexpr vtkIdType numPlanes = 6;
vtkNew<vtkPoints> pts;
pts->SetDataTypeToFloat();
pts->SetNumberOfPoints(numPts);
for (auto i = 0; i < numPts; ++i)
{
pts->SetPoint(i, vtkMath::Random(-1, 1), vtkMath::Random(-1, 1), vtkMath::Random(-1, 1));
}
// Define the plane normals
std::vector<double> planes(numPlanes * 4, 0);
planes[0] = -1; // define six normals (-x,+x, -y,+y, -z,+z)
planes[4] = 1;
planes[9] = -1;
planes[13] = 1;
planes[18] = -1;
planes[22] = 1;
// // Use a functor to compute the planes
HullFunctor hull(pts, planes);
vtkSMPTools::For(0, numPts, hull);
std::cout << "Planes (functor): " << planes[3] << ", " << planes[7] << ", " << planes[11] << ", "
<< planes[15] << ", " << planes[19] << ", " << planes[23] << "\n";
// Use a lambda to compute the planes
planes[3] = 0; // reset v
planes[7] = 0;
planes[11] = 0;
planes[15] = 0;
planes[19] = 0;
planes[23] = 0;
vtkSMPTools::For(0, numPts,
[&](vtkIdType ptId, vtkIdType endPtId)
{
for (; ptId < endPtId; ++ptId)
{
double v, coord[3];
pts->GetPoint(ptId, coord);
for (auto j = 0; j < numPlanes; j++)
{
v = -(planes[j * 4 + 0] * coord[0] + planes[j * 4 + 1] * coord[1] +
planes[j * 4 + 2] * coord[2]);
// negative means further in + direction of plane
if (v < planes[j * 4 + 3])
{
planes[j * 4 + 3] = v;
}
}
}
}); // end lambda
std::cout << "Planes (lambda): " << planes[3] << ", " << planes[7] << ", " << planes[11] << ", "
<< planes[15] << ", " << planes[19] << ", " << planes[23] << "\n";
// Compute bounds using Initialize() and Reduce().
vtkFloatArray* ptsArray = vtkFloatArray::SafeDownCast(pts->GetData());
BoundsFunctor calcBounds(ptsArray);
vtkSMPTools::For(0, numPts, calcBounds);
std::array<double, 6>& bds = calcBounds.Bounds;
std::cout << "Bounds (: " << bds[0] << "," << bds[1] << ", " << bds[2] << "," << bds[3] << ", "
<< bds[4] << "," << bds[5] << ")\n";
// Now exercise atomics
vtkNew<vtkMultiThreader> mt;
mt->SetSingleMethod(MyFunction, nullptr);
mt->SetNumberOfThreads(NumThreads);
mt->SingleMethodExecute();
std::cout << TotalAtomic.load() << endl;
return EXIT_SUCCESS;
}
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