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CellLocatorVisualization

Repository source: CellLocatorVisualization

Description

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

Note

It is not desirable to have CellsPerBucket 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 question about this example, please use the VTK Discourse Forum

Code

CellLocatorVisualization.cxx

#include <vtkActor.h>
#include <vtkCallbackCommand.h>
#include <vtkCellLocator.h>
#include <vtkMath.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkProperty2D.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSliderRepresentation2D.h>
#include <vtkSliderWidget.h>
#include <vtkSphereSource.h>
#include <vtkTextProperty.h>

namespace {

class vtkSliderCallback : public vtkCallbackCommand
{
public:
  static vtkSliderCallback* New()
  {
    return new vtkSliderCallback;
  }
  vtkSliderCallback() : CellLocator(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->CellLocator->GenerateRepresentation(this->Level, this->PolyData);
    this->Renderer->Render();
  }

  vtkCellLocator* CellLocator;
  int Level;
  vtkPolyData* PolyData;
  vtkRenderer* Renderer;
};

void SetSliderColors(vtkSliderRepresentation2D* slider);

} // namespace

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

  vtkNew<vtkSphereSource> inputSource;
  inputSource->SetPhiResolution(10);
  inputSource->SetThetaResolution(10);
  inputSource->Update();

  vtkNew<vtkPolyDataMapper> pointsMapper;
  pointsMapper->SetInputConnection(inputSource->GetOutputPort());

  vtkNew<vtkActor> pointsActor;
  pointsActor->SetMapper(pointsMapper);
  pointsActor->GetProperty()->SetInterpolationToFlat();
  pointsActor->GetProperty()->SetColor(
      colors->GetColor3d("MistyRose").GetData());

  // Create the tree.
  vtkNew<vtkCellLocator> cellLocator;
  cellLocator->SetDataSet(inputSource->GetOutput());
  cellLocator->BuildLocator();

  // Initialize the representation.
  vtkNew<vtkPolyData> polydata;
  cellLocator->GenerateRepresentation(0, polydata);

  vtkNew<vtkPolyDataMapper> locatorTreeMapper;
  locatorTreeMapper->SetInputData(polydata);

  vtkNew<vtkActor> locatorTreeActor;
  locatorTreeActor->SetMapper(locatorTreeMapper);
  locatorTreeActor->GetProperty()->SetInterpolationToFlat();
  locatorTreeActor->GetProperty()->SetRepresentationToWireframe();
  locatorTreeActor->GetProperty()->SetColor(
      colors->GetColor3d("Gold").GetData());

  // A renderer and render window.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("CellLocatorVisualization");

  // An interactor.
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene.
  renderer->AddActor(pointsActor);
  renderer->AddActor(locatorTreeActor);
  renderer->SetBackground(colors->GetColor3d("DarkSlateGray").GetData());

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

  vtkNew<vtkSliderRepresentation2D> sliderRep;
  sliderRep->SetMinimumValue(0);
  sliderRep->SetMaximumValue(cellLocator->GetLevel());
  sliderRep->SetValue(0);
  sliderRep->SetTitleText("MaxPointsPerRegion");
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint1Coordinate()->SetValue(.2, .1);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint2Coordinate()->SetValue(.8, .1);
  sliderRep->SetSliderLength(0.075);
  sliderRep->SetSliderWidth(0.05);
  sliderRep->SetEndCapLength(0.05);
  SetSliderColors(sliderRep);

  vtkNew<vtkSliderWidget> sliderWidget;
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  vtkNew<vtkSliderCallback> callback;
  callback->CellLocator = cellLocator;
  callback->PolyData = polydata;
  callback->Renderer = renderer;

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

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

namespace {

void SetSliderColors(vtkSliderRepresentation2D* slider)
{
  vtkNew<vtkNamedColors> colors;
  // Set color properties:
  // Change the color of the knob that slides.
  slider->GetSliderProperty()->SetColor(colors->GetColor3d("Peru").GetData());
  // Change the color of the text indicating what the slider controls.
  slider->GetTitleProperty()->SetColor(colors->GetColor3d("Silver").GetData());
  // Change the color of the text displaying the value.
  slider->GetLabelProperty()->SetColor(colors->GetColor3d("Silver").GetData());
  // Change the color of the knob when the mouse is held on it.
  slider->GetSelectedProperty()->SetColor(
      colors->GetColor3d("DeepPink").GetData());
  // Change the color of the bar.
  slider->GetTubeProperty()->SetColor(colors->GetColor3d("Teal").GetData());
  // Change the color of the ends of the bar.
  slider->GetCapProperty()->SetColor(colors->GetColor3d("Teal").GetData());
}

} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(CellLocatorVisualization)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  FiltersSources
  InteractionStyle
  InteractionWidgets
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "CellLocatorVisualization: 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(CellLocatorVisualization MACOSX_BUNDLE CellLocatorVisualization.cxx )
  target_link_libraries(CellLocatorVisualization PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS CellLocatorVisualization
  MODULES ${VTK_LIBRARIES}
)

Download and Build CellLocatorVisualization

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

cd CellLocatorVisualization/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:

./CellLocatorVisualization

WINDOWS USERS

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