# KDTreeTimingDemo

VTKExamples/Cxx/DataStructures/KDTreeTimingDemo

### Code

KDTreeTimingDemo.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>
    #include <vtkAxis.h>
    #include <vtkTimerLog.h>
    #include <vtkMath.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkIdList.h>
    #include <vtkKdTreePointLocator.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderWindow.h>
    #include <vtkSmartPointer.h>
    #include <vtkChartXY.h>
    #include <vtkPlot.h>
    #include <vtkTable.h>
    #include <vtkFloatArray.h>
    #include <vtkContextView.h>
    #include <vtkContextScene.h>
    #include <vtkSphereSource.h>

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

    static void RandomPointInBounds(vtkPolyData* polydata, double p[3]);
    static double TimeKDTree(vtkPolyData* polydata, int maxPoints, int numberOfTrials);

    int main(int, char *[])
    {
      vtkSmartPointer<vtkSphereSource> reader =
        vtkSmartPointer<vtkSphereSource>::New();
      reader->SetThetaResolution(30);
      reader->SetPhiResolution(30);
      reader->Update();

      std::cout << "Timing octree..." << std::endl;
      std::vector<std::pair<int, double> > results;
      int numberOfTrials = 1000;
      for(int i = 1; i < 20; i++)
      {
        double t = TimeKDTree(reader->GetOutput(), i, numberOfTrials);
        std::pair<int, double> result(i,t);
        results.push_back(result);
      }

      // Create a table with some points in it
      vtkSmartPointer<vtkTable> table =
        vtkSmartPointer<vtkTable>::New();

      vtkSmartPointer<vtkFloatArray> maxPointsPerRegion =
        vtkSmartPointer<vtkFloatArray>::New();
      maxPointsPerRegion->SetName("MaxPointsPerRegion");
      table->AddColumn(maxPointsPerRegion);

      vtkSmartPointer<vtkFloatArray> runtime =
        vtkSmartPointer<vtkFloatArray>::New();
      runtime->SetName("Run time");
      table->AddColumn(runtime);

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

      // Set up the view
      vtkSmartPointer<vtkContextView> view =
        vtkSmartPointer<vtkContextView>::New();
      view->GetRenderer()->SetBackground(1.0, 1.0, 1.0);

      // Add multiple line plots, setting the colors etc
      vtkSmartPointer<vtkChartXY> chart =
        vtkSmartPointer<vtkChartXY>::New();
      view->GetScene()->AddItem(chart);
      vtkPlot *line = chart->AddPlot(vtkChart::LINE);
    #if VTK_MAJOR_VERSION <= 5
      line->SetInput(table, 0, 1);
    #else
      line->SetInputData(table, 0, 1);
    #endif
      line->SetColor(0, 255, 0, 255);
      line->SetWidth(3.0);
      line->GetXAxis()->SetTitle("Max Points Per Region");
      line->GetYAxis()->SetTitle("Run time");

      view->GetRenderWindow()->SetMultiSamples(0);

      // Start interactor
      view->GetInteractor()->Initialize();
      view->GetInteractor()->Start();

      return EXIT_SUCCESS;
    }

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

      double x = bounds[0] + (bounds[1] - bounds[0]) * vtkMath::Random(0.0,1.0);
      double y = bounds[2] + (bounds[3] - bounds[2]) * vtkMath::Random(0.0,1.0);
      double z = bounds[4] + (bounds[5] - bounds[4]) * vtkMath::Random(0.0,1.0);

      p[0] = x;
      p[1] = y;
      p[2] = z;
    }

    double TimeKDTree(vtkPolyData* polydata, int maxLevel, int numberOfTrials)
    {
      vtkSmartPointer<vtkTimerLog> timer =
        vtkSmartPointer<vtkTimerLog>::New();
      timer->StartTimer();

      vtkMath::RandomSeed(0); // this should be changed to time(NULL) to get random behavior

      // Create the tree
      vtkSmartPointer<vtkKdTreePointLocator> kdtree =
        vtkSmartPointer<vtkKdTreePointLocator>::New();
      kdtree->SetDataSet(polydata);
      kdtree->AutomaticOff();
      kdtree->SetMaxLevel(maxLevel);
      kdtree->BuildLocator();

    //  std::cout << "With maxLevel = " << maxLevel << " there are " << kdtree->GetNumberOfLeafNodes() << " leaf nodes." << std::endl;

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

      timer->StopTimer();

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

      return timer->GetElapsedTime();
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(KDTreeTimingDemo)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(KDTreeTimingDemo MACOSX_BUNDLE KDTreeTimingDemo.cxx)

    target_link_libraries(KDTreeTimingDemo ${VTK_LIBRARIES})

### Download and Build KDTreeTimingDemo

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

    cd KDTreeTimingDemo/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:

    ./KDTreeTimingDemo

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