VTK/Examples/Cxx/PolyData/PointLocator

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VTK Examples Baseline PolyData TestPointLocator.png

Create a point locator for a set of points. The 'n' (next) and 'p' (previous) keys change the resolution of the cells.

PointLocator.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkPolyDataMapper.h>
#include <vtkObjectFactory.h>
#include <vtkPointSource.h>
#include <vtkPolyData.h>
#include <vtkPointLocator.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
 
class KeyPressInteractorStyle3 : public vtkInteractorStyleTrackballCamera
{
  public:
    static KeyPressInteractorStyle3* New();
 
    KeyPressInteractorStyle3() : PointsPerBucket(1) {}
 
    virtual void OnChar() 
    {
      vtkRenderWindowInteractor *rwi = this->Interactor;		
      char ch = rwi->GetKeyCode() ;
 
      switch (ch) 
      {
        case 'n':
          cout << "Next." << endl;
          this->PointsPerBucket++;
          break;
        case 'p':
          cout << "Previous." << endl;
          if(this->PointsPerBucket > 1)
            {
            this->PointsPerBucket--;
            }
          break ;
        default:
          std::cout << "An unhandled key was pressed." << std::endl;
          break;
      }
 
      std::cout << "PointsPerBucket = " << this->PointsPerBucket << std::endl;
 
      // Create the tree
      pointLocator->SetNumberOfPointsPerBucket(this->PointsPerBucket);
      pointLocator->BuildLocator();
      pointLocator->GenerateRepresentation(1, polydata);
 
      renderWindow->Render();
 
      // Forward events
      vtkInteractorStyleTrackballCamera::OnChar();
    }
 
    vtkPointLocator* pointLocator;
    vtkRenderWindow* renderWindow;
    vtkPolyData* polydata;
 
  private:
    unsigned int PointsPerBucket;
};
 
vtkStandardNewMacro(KeyPressInteractorStyle3);
 
int main(int, char *[])
{
  vtkSmartPointer<vtkPointSource> pointSource = 
    vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(4000);
  pointSource->Update();
 
  // Create the tree
  vtkSmartPointer<vtkPointLocator> pointLocator = 
    vtkSmartPointer<vtkPointLocator>::New();
  pointLocator->SetDataSet(pointSource->GetOutput());
  pointLocator->AutomaticOn();
  pointLocator->SetNumberOfPointsPerBucket(2);
  pointLocator->BuildLocator();
 
  std::cout << "There are " << pointLocator->GetLevel() << " levels." << std::endl;
  std::cout << "There are " << pointLocator->GetNumberOfPointsPerBucket() 
            << " points per bucket." << endl;
 
  vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
  pointLocator->GenerateRepresentation(pointLocator->GetLevel(), polydata);
 
  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInput(polydata);
#else
  mapper->SetInputData(polydata);
#endif
 
  vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
 
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
 
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  vtkSmartPointer<KeyPressInteractorStyle3> style = 
    vtkSmartPointer<KeyPressInteractorStyle3>::New();
  style->pointLocator = pointLocator;
  style->renderWindow = renderWindow;
  style->polydata = polydata;
 
  renderWindowInteractor->SetInteractorStyle( style );
 
  renderer->AddActor(actor);
  renderer->SetBackground(1,1,1); // Background color white
 
  renderWindow->Render();
 
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
 
PROJECT(PointLocator)
 
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
 
add_executable(PointLocator MACOSX_BUNDLE PointLocator.cxx)
 
if(VTK_LIBRARIES)
  target_link_libraries(PointLocator ${VTK_LIBRARIES})
else()
  target_link_libraries(PointLocator vtkHybrid vtkWidgets)
endif()

Download and Build PointLocator

Click here to download PointLocator. and its CMakeLists.txt file.

Once the tarball PointLocator.tar has been downloaded and extracted,

cd PointLocator/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:

./PointLocator

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.

Output image is bad.