# Frustum

VTKExamples/Cxx/GeometricObjects/Frustum

### Description

This example gets the frustum from a camera and displays it on the screen.

Other Languages

See (Python), (Java), (CSharp)

### Code

Frustum.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkFrustumSource.h>
    #include <vtkMapper.h>
    #include <vtkNamedColors.h>
    #include <vtkPlanes.h>
    #include <vtkPolyData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkShrinkPolyData.h>
    #include <vtkSmartPointer.h>

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

      vtkSmartPointer<vtkCamera> camera =
        vtkSmartPointer<vtkCamera>::New();
      camera->SetClippingRange(.1, .4);
      double planesArray[24];

      camera->GetFrustumPlanes(1.0, planesArray);

      vtkSmartPointer<vtkPlanes> planes =
        vtkSmartPointer<vtkPlanes>::New();
      planes->SetFrustumPlanes(planesArray);

      vtkSmartPointer<vtkFrustumSource> frustumSource =
        vtkSmartPointer<vtkFrustumSource>::New();
      frustumSource->ShowLinesOff();
      frustumSource->SetPlanes(planes);

      vtkSmartPointer<vtkShrinkPolyData> shrink =
        vtkSmartPointer<vtkShrinkPolyData>::New();
      shrink->SetInputConnection(frustumSource->GetOutputPort());
      shrink->SetShrinkFactor(.9);

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(shrink->GetOutputPort());

      vtkSmartPointer<vtkProperty> back =
        vtkSmartPointer<vtkProperty>::New();
      back->SetColor(colors->GetColor3d("Tomato").GetData());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->EdgeVisibilityOn();
      actor->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
      actor->SetBackfaceProperty(back);

      // a renderer and render window
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetWindowName("Frustum");
      renderWindow->AddRenderer(renderer);

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

      // add the actors to the scene
      renderer->AddActor(actor);
      renderer->SetBackground(colors->GetColor3d("Silver").GetData());

      // Position the camera so that we can see the frustum
      renderer->GetActiveCamera()->SetPosition(1, 0, 0);
      renderer->GetActiveCamera()->SetFocalPoint(0, 0, 0);
      renderer->GetActiveCamera()->SetViewUp(0, 1, 0);
      renderer->GetActiveCamera()->Azimuth(30);
      renderer->GetActiveCamera()->Elevation(30);
      renderer->ResetCamera();

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

      // begin mouse interaction
      renderWindowInteractor->Start();
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Frustum)

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

### Download and Build Frustum

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

    cd Frustum/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:

    ./Frustum

WINDOWS USERS

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