Skip to content

OctreeTimingDemo

Repository source: OctreeTimingDemo

Description

This example runs several closest point queries on octrees with varying MaxPointsPerRegion and plots the result.

Your timing graph will be different when compared to the above illustration.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

OctreeTimingDemo.cxx

#include <vtkAxis.h>
#include <vtkChartXY.h>
#include <vtkContextView.h>
#include <vtkFloatArray.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkOctreePointLocator.h>
#include <vtkPlot.h>
#include <vtkPolyData.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>
#include <vtkTable.h>
#include <vtkTimerLog.h>

#include <time.h>
#include <vector>

namespace {
// void RandomPointInBounds(vtkPolyData* polydata, double p[3]);
void RandomPointInBounds(vtkPolyData* polydata, double p[3],
                         vtkMinimalStandardRandomSequence* rng);

double TimeOctree(vtkPolyData* polydata, int maxPoints, int numberOfTrials,
                  vtkMinimalStandardRandomSequence* rng);
} // namespace

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkSphereSource> reader;
  reader->SetThetaResolution(30);
  reader->SetPhiResolution(30);
  reader->Update();

  vtkNew<vtkMinimalStandardRandomSequence> rng;
  rng->SetSeed(8775070);
  // rng->SetSeed(0);

  std::cout << "Timing octree..." << std::endl;
  std::vector<std::pair<int, double>> results;
  int numberOfTrials = 1000;
  for (int i = 1; i < 100; i++)
  {
    double t = TimeOctree(reader->GetOutput(), i, numberOfTrials, rng);
    std::pair<int, double> result(i, t);
    results.push_back(result);
  }

  // Create a table with some points in it
  vtkNew<vtkTable> table;

  vtkNew<vtkFloatArray> maxPointsPerRegion;
  maxPointsPerRegion->SetName("MaxPointsPerRegion");
  table->AddColumn(maxPointsPerRegion);

  vtkNew<vtkFloatArray> runtime;
  runtime->SetName("Run time");
  table->AddColumn(runtime);

  // Fill in the table with some example values
  size_t numPoints = results.size();
  table->SetNumberOfRows(static_cast<vtkIdType>(numPoints));
  for (size_t i = 0; i < numPoints; ++i)
  {
    table->SetValue(static_cast<vtkIdType>(i), 0, results[i].first);
    table->SetValue(static_cast<vtkIdType>(i), 1, results[i].second);
    std::cout << "Put " << results[i].first << " " << results[i].second
              << " in the table." << std::endl;
  }

  // Set up the view
  vtkNew<vtkContextView> view;
  view->GetRenderer()->SetBackground(colors->GetColor3d("White").GetData());
  view->GetRenderWindow()->SetWindowName("OctreeTimingDemo");

  // Add multiple line plots, setting the colors etc
  vtkNew<vtkChartXY> chart;
  view->GetScene()->AddItem(chart);
  vtkPlot* line = chart->AddPlot(vtkChart::LINE);
  line->SetInputData(table, 0, 1);
  auto lineColor = colors->HTMLColorToRGBA("Lime").GetData();
  line->SetColor(lineColor[0], lineColor[1], lineColor[2], lineColor[3]);
  line->SetWidth(3.0);
  line->GetXAxis()->SetTitle("Max Points Per Region");
  line->GetYAxis()->SetTitle("Run time");

  // Set up an interactor and start
  view->Render();
  view->GetInteractor()->SetRenderWindow(view->GetRenderWindow());
  view->GetInteractor()->Initialize();
  view->GetInteractor()->Start();

  return EXIT_SUCCESS;
}

namespace {
void RandomPointInBounds(vtkPolyData* polydata, double p[3],
                         vtkMinimalStandardRandomSequence* rng)
{
  double bounds[6];
  polydata->GetBounds(bounds);

  for (auto i = 0; i < 3; ++i)
  {
    p[i] = bounds[i * 2] +
        (bounds[i * 2 + 1] - bounds[i * 2]) * rng->GetRangeValue(0.0, 1.0);
    rng->Next();
  }
}

double TimeOctree(vtkPolyData* polydata, int maxPoints, int numberOfTrials,
                  vtkMinimalStandardRandomSequence* rng)
{
  vtkNew<vtkTimerLog> timer;
  timer->StartTimer();

  // Create the tree
  vtkNew<vtkOctreePointLocator> octree;
  octree->SetDataSet(polydata);
  octree->SetMaximumPointsPerRegion(maxPoints);
  octree->BuildLocator();

  std::cout << "With maxPoints = " << maxPoints << " there are "
            << octree->GetNumberOfLeafNodes() << " leaf nodes." << std::endl;

  for (int i = 0; i < numberOfTrials; i++)
  {
    double p[3];
    RandomPointInBounds(polydata, p, rng);
    // vtkIdType iD = octree->FindClosestPoint(p);
    octree->FindClosestPoint(p);
  }

  timer->StopTimer();

  std::cout << "Octree took " << timer->GetElapsedTime() << std::endl;

  return timer->GetElapsedTime();
}

} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(OctreeTimingDemo)

find_package(VTK COMPONENTS 
  ChartsCore
  CommonColor
  CommonCore
  CommonDataModel
  CommonSystem
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
  ViewsContext2D
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "OctreeTimingDemo: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(OctreeTimingDemo MACOSX_BUNDLE OctreeTimingDemo.cxx )
  target_link_libraries(OctreeTimingDemo PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS OctreeTimingDemo
  MODULES ${VTK_LIBRARIES}
)

Download and Build OctreeTimingDemo

Click here to download OctreeTimingDemo and its CMakeLists.txt file. Once the tarball OctreeTimingDemo.tar has been downloaded and extracted,

cd OctreeTimingDemo/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./OctreeTimingDemo

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.