# CylinderExample

VTKExamples/Cxx/GeometricObjects/CylinderExample

### Description

This example creates a minimal visualization program, demonstrating VTK's basic rendering and pipeline creation.

Note

This original C++ source code for this example is here.

Other Languages

See (Python), (Java)

### Code

CylinderExample.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkCylinderSource.h>
    #include <vtkNamedColors.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSmartPointer.h>

    #include <array>

    int main(int, char *[]) {
      vtkSmartPointer<vtkNamedColors> colors =
          vtkSmartPointer<vtkNamedColors>::New();

      // Set the background color.
      std::array<unsigned char, 4> bkg{{26, 51, 102, 255}};
      colors->SetColor("BkgColor", bkg.data());

      // This creates a polygonal cylinder model with eight circumferential facets
      // (i.e, in practice an octagonal prism).
      vtkSmartPointer<vtkCylinderSource> cylinder =
          vtkSmartPointer<vtkCylinderSource>::New();
      cylinder->SetResolution(8);

      // The mapper is responsible for pushing the geometry into the graphics
      // library. It may also do color mapping, if scalars or other attributes are
      // defined.
      vtkSmartPointer<vtkPolyDataMapper> cylinderMapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      cylinderMapper->SetInputConnection(cylinder->GetOutputPort());

      // The actor is a grouping mechanism: besides the geometry (mapper), it
      // also has a property, transformation matrix, and/or texture map.
      // Here we set its color and rotate it around the X and Y axes.
      vtkSmartPointer<vtkActor> cylinderActor = vtkSmartPointer<vtkActor>::New();
      cylinderActor->SetMapper(cylinderMapper);
      cylinderActor->GetProperty()->SetColor(
          colors->GetColor4d("Tomato").GetData());
      cylinderActor->RotateX(30.0);
      cylinderActor->RotateY(-45.0);

      // The renderer generates the image
      // which is then displayed on the render window.
      // It can be thought of as a scene to which the actor is added
      vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
      renderer->AddActor(cylinderActor);
      renderer->SetBackground(colors->GetColor3d("BkgColor").GetData());
      // Zoom in a little by accessing the camera and invoking its "Zoom" method.
      renderer->ResetCamera();
      renderer->GetActiveCamera()->Zoom(1.5);

      // The render window is the actual GUI window
      // that appears on the computer screen
      vtkSmartPointer<vtkRenderWindow> renderWindow =
          vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(300, 300);
      renderWindow->AddRenderer(renderer);
      renderWindow->SetWindowName("Cylinder");

      // The render window interactor captures mouse events
      // and will perform appropriate camera or actor manipulation
      // depending on the nature of the events.
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
          vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      // This starts the event loop and as a side effect causes an initial render.
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(CylinderExample)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkFiltersSources
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping CylinderExample: ${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(CylinderExample MACOSX_BUNDLE CylinderExample.cxx )
      target_link_libraries(CylinderExample PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(CylinderExample MACOSX_BUNDLE CylinderExample.cxx )
      target_link_libraries(CylinderExample PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS CylinderExample
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build CylinderExample

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

    cd CylinderExample/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:

    ./CylinderExample

WINDOWS USERS

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