# TubeFilter

VTKExamples/Cxx/PolyData/TubeFilter

### Description

This example creates a tube around a line. This is helpful because when you zoom the camera, the thickness of a line remains constant, while the thickness of a tube varies.

### Code

TubeFilter.cxx

    #include <vtkSmartPointer.h>
    #include <vtkLine.h>
    #include <vtkCellArray.h>
    #include <vtkTubeFilter.h>
    #include <vtkLineSource.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkProperty.h>

    /*
     * This example creates a tube around a line.
     * This is helpful because when you zoom the camera,
     * the thickness of a line remains constant,
     * while the thickness of a tube varies.
     * */

    int main(int, char *[])
    {
      // Create a line
      vtkSmartPointer<vtkLineSource> lineSource =
        vtkSmartPointer<vtkLineSource>::New();
      lineSource->SetPoint1(1.0, 0.0, 0.0);
      lineSource->SetPoint2(0.0, 1.0, 0.0);

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> lineMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      lineMapper->SetInputConnection(lineSource->GetOutputPort());
      vtkSmartPointer<vtkActor> lineActor =
        vtkSmartPointer<vtkActor>::New();
      lineActor->GetProperty()->SetColor(0.0,0.0,0.1); // Give some color to the line
      lineActor->SetMapper(lineMapper);

      // Create a tube (cylinder) around the line
      vtkSmartPointer<vtkTubeFilter> tubeFilter =
        vtkSmartPointer<vtkTubeFilter>::New();
      tubeFilter->SetInputConnection(lineSource->GetOutputPort());
      tubeFilter->SetRadius(.025); //default is .5
      tubeFilter->SetNumberOfSides(50);
      tubeFilter->Update();

      // Create a mapper and actor
      vtkSmartPointer<vtkPolyDataMapper> tubeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      tubeMapper->SetInputConnection(tubeFilter->GetOutputPort());
      vtkSmartPointer<vtkActor> tubeActor =
        vtkSmartPointer<vtkActor>::New();
      tubeActor->GetProperty()->SetOpacity(0.5); //Make the tube have some transparency.
      tubeActor->SetMapper(tubeMapper);

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // Add the actor to the scene
      renderer->AddActor(tubeActor);
      renderer->AddActor(lineActor);
      renderer->SetBackground(0,1,0);

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(TubeFilter)

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

    add_executable(TubeFilter MACOSX_BUNDLE TubeFilter.cxx )

    target_link_libraries(TubeFilter ${VTK_LIBRARIES})

### Download and Build TubeFilter

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

    cd TubeFilter/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:

    ./TubeFilter

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.