PointLocatorVisualization

VTKEx/Cxx/PolyData/PointLocatorVisualization

Description

The idea of this example is to navigate levels of a uniform spatial tree vtkPointLocator) using a slider.

Note

It is not desirable to have PointsPerBucket set "too small". This is because at some point, refining a bucket will result in each cell in that bucket to also be in the bucket's children. This only wastes memory and computation. The value that is "too small" is dependent on the grid but in general a value between 10 and 100 should work well (the default value is 25).

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

PointLocatorVisualization.cxx

#include <vtkPointSource.h>
#include <vtkSphereSource.h>
#include <vtkPointLocator.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkSliderWidget.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>
#include <vtkCommand.h>
#include <vtkWidgetEvent.h>
#include <vtkCallbackCommand.h>
#include <vtkWidgetEventTranslator.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkSliderWidget.h>
#include <vtkSliderRepresentation2D.h>
#include <vtkProperty.h>

#include <vtkMath.h>

class vtkSliderCallback : public vtkCommand
{
public:
  static vtkSliderCallback *New()
  {
    return new vtkSliderCallback;
  }
  vtkSliderCallback():PointLocator(0), Level(0), PolyData(0), Renderer(0){}

  virtual void Execute(vtkObject *caller, unsigned long, void*)
  {
    vtkSliderWidget *sliderWidget =
      reinterpret_cast<vtkSliderWidget*>(caller);
    this->Level = vtkMath::Round(static_cast<vtkSliderRepresentation *>(sliderWidget->GetRepresentation())->GetValue());
    this->PointLocator->GenerateRepresentation(this->Level, this->PolyData);
    this->Renderer->Render();
  }

  vtkPointLocator* PointLocator;
  int Level;
  vtkPolyData* PolyData;
  vtkRenderer* Renderer;
};

int main (int, char *[])
{
  vtkSmartPointer<vtkSphereSource> inputSource =
    vtkSmartPointer<vtkSphereSource>::New();
  inputSource->SetPhiResolution(10);
  inputSource->SetThetaResolution(10);
  inputSource->Update();

  vtkSmartPointer<vtkPolyDataMapper> pointsMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  pointsMapper->SetInputConnection(inputSource->GetOutputPort());

  vtkSmartPointer<vtkActor> pointsActor =
    vtkSmartPointer<vtkActor>::New();
  pointsActor->SetMapper(pointsMapper);
  pointsActor->GetProperty()->SetInterpolationToFlat();

  // Create the tree
  vtkSmartPointer<vtkPointLocator> pointLocator =
    vtkSmartPointer<vtkPointLocator>::New();
  pointLocator->SetDataSet(inputSource->GetOutput());
  pointLocator->BuildLocator();

  // Initialize the representation
  vtkSmartPointer<vtkPolyData> polydata =
    vtkSmartPointer<vtkPolyData>::New();
  pointLocator->GenerateRepresentation(0, polydata);

  vtkSmartPointer<vtkPolyDataMapper> locatorTreeMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  locatorTreeMapper->SetInputData(polydata);

  vtkSmartPointer<vtkActor> locatorTreeActor =
    vtkSmartPointer<vtkActor>::New();
  locatorTreeActor->SetMapper(locatorTreeMapper);
  locatorTreeActor->GetProperty()->SetInterpolationToFlat();
  locatorTreeActor->GetProperty()->SetRepresentationToWireframe();

  // A renderer and render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  // An interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene
  renderer->AddActor(pointsActor);
  renderer->AddActor(locatorTreeActor);

  // Render an image (lights and cameras are created automatically)
  renderWindow->Render();

  vtkSmartPointer<vtkSliderRepresentation2D> sliderRep =
    vtkSmartPointer<vtkSliderRepresentation2D>::New();
  sliderRep->SetMinimumValue(0);
  sliderRep->SetMaximumValue(pointLocator->GetLevel());
  sliderRep->SetValue(0);
  sliderRep->SetTitleText("MaxPointsPerRegion");
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint1Coordinate()->SetValue(.2, .2);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint2Coordinate()->SetValue(.8, .2);
  sliderRep->SetSliderLength(0.075);
  sliderRep->SetSliderWidth(0.05);
  sliderRep->SetEndCapLength(0.05);

  vtkSmartPointer<vtkSliderWidget> sliderWidget =
    vtkSmartPointer<vtkSliderWidget>::New();
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  vtkSmartPointer<vtkSliderCallback> callback =
    vtkSmartPointer<vtkSliderCallback>::New();
  callback->PointLocator = pointLocator;
  callback->PolyData = polydata;
  callback->Renderer = renderer;

  sliderWidget->AddObserver(vtkCommand::InteractionEvent,callback);

  renderWindowInteractor->Initialize();
  renderWindow->Render();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(PointLocatorVisualization)

find_package(VTK COMPONENTS 
  vtkvtkCommonCore
  vtkvtkCommonDataModel
  vtkvtkFiltersSources
  vtkvtkInteractionStyle
  vtkvtkInteractionWidgets
  vtkvtkRenderingContextOpenGL2
  vtkvtkRenderingCore
  vtkvtkRenderingFreeType
  vtkvtkRenderingGL2PSOpenGL2
  vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping PointLocatorVisualization: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(PointLocatorVisualization MACOSX_BUNDLE PointLocatorVisualization.cxx )
  target_link_libraries(PointLocatorVisualization PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(PointLocatorVisualization MACOSX_BUNDLE PointLocatorVisualization.cxx )
  target_link_libraries(PointLocatorVisualization PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS PointLocatorVisualization
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build PointLocatorVisualization

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

cd PointLocatorVisualization/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:

./PointLocatorVisualization

WINDOWS USERS

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