# Frustum

VTKExamples/Cxx/GeometricObjects/Frustum

### Description

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

### Code

Frustum.cxx

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

    int main(int, char *[])
    {
      vtkSmartPointer<vtkCamera> camera =
        vtkSmartPointer<vtkCamera>::New();
      double planesArray[24];

      camera->GetFrustumPlanes(1, planesArray);

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

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

      vtkPolyData* frustum = frustumSource->GetOutput();

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
    #if VTK_MAJOR_VERSION <= 5
      mapper->SetInput(frustum);
    #else
      mapper->SetInputData(frustum);
    #endif

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      // a renderer and render window
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      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( .2, .1, .3); // Background color dark purple

      // 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 2.8)

    PROJECT(Frustum)

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

    add_executable(Frustum MACOSX_BUNDLE Frustum.cxx )

    target_link_libraries(Frustum ${VTK_LIBRARIES})

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