PolyDataConnectivityFilter SpecifiedRegion

vtk-examples/Cxx/PolyData/PolyDataConnectivityFilter_SpecifiedRegion

Description¶

This example creates two spheres and combines them together into one polydata. The vtkPolyDataConnectivityFilter is used to find the two spheres as they are separate regions (disconnected). If region 0 is selected, the small sphere is extracted. If region 1 is selected, the large sphere is extracted.

The original vtkPolyData is red, on top. The extracted region is yellow, on the bottom.

Note

Contrast this with PolyDataConnectivityFilter_LargestRegion.

Note

Contributed by: Jinyoung Hwang

Other languages

See (CSharp)

Question

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

Code¶

PolyDataConnectivityFilter_SpecifiedRegion.cxx

#include <vtkActor.h>
#include <vtkAppendPolyData.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyDataConnectivityFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>

#include <vtkNamedColors.h>

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

  vtkNew<vtkSphereSource> sphereSource1;
  sphereSource1->SetRadius(5);

  vtkNew<vtkSphereSource> sphereSource2;
  sphereSource2->SetRadius(10);
  sphereSource2->SetCenter(25, 0, 0);

  vtkNew<vtkAppendPolyData> appendFilter;
  appendFilter->AddInputConnection(sphereSource1->GetOutputPort());
  appendFilter->AddInputConnection(sphereSource2->GetOutputPort());

  vtkNew<vtkPolyDataConnectivityFilter> connectivityFilter;
  connectivityFilter->SetInputConnection(appendFilter->GetOutputPort());
  connectivityFilter->SetExtractionModeToSpecifiedRegions();
  connectivityFilter->AddSpecifiedRegion(0); // select the region to extract
                                             // here
  connectivityFilter->Update();

  // Create a mapper and actor for original data
  vtkNew<vtkPolyDataMapper> originalMapper;
  originalMapper->SetInputConnection(appendFilter->GetOutputPort());

  vtkNew<vtkActor> originalActor;
  originalActor->SetMapper(originalMapper);
  originalActor->GetProperty()->SetColor(
      colors->GetColor3d("Tomato").GetData());

  // create a mapper and actor for extracted data
  vtkNew<vtkPolyDataMapper> extractedMapper;
  extractedMapper->SetInputConnection(connectivityFilter->GetOutputPort());

  vtkNew<vtkActor> extractedActor;
  extractedActor->SetMapper(extractedMapper);
  extractedActor->GetProperty()->SetColor(
      colors->GetColor3d("Banana").GetData());
  extractedActor->SetPosition(0, -20, 0);

  // create a renderer
  vtkNew<vtkRenderer> renderer;
  renderer->AddActor(originalActor);
  renderer->AddActor(extractedActor);
  renderer->GradientBackgroundOn();
  renderer->SetBackground(colors->GetColor3d("Gold").GetData());
  renderer->SetBackground2(colors->GetColor3d("Silver").GetData());

  // create a render window
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("PolyDataConnectivityFilter_SpecifiedRegion");

  // create an interactor
  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);
  renderWindow->Render();
  interactor->Initialize();
  interactor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(PolyDataConnectivityFilter_SpecifiedRegion)

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

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

Download and Build PolyDataConnectivityFilter_SpecifiedRegion¶

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

cd PolyDataConnectivityFilter_SpecifiedRegion/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:

./PolyDataConnectivityFilter_SpecifiedRegion

WINDOWS USERS

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