# Hexahedron

VTKExamples/Cxx/GeometricObjects/Hexahedron

### Description

This example creates eight points and creates a hexahedron from the points.

### Code

Hexahedron.cxx

    #include <vtkVersion.h>
    #include <vtkCellArray.h>
    #include <vtkPoints.h>
    #include <vtkHexahedron.h>
    #include <vtkUnstructuredGrid.h>

    #include <vtkSmartPointer.h>
    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>

    int main(int, char *[])
    {
      // Setup the coordinates of eight points
      // (the two faces must be in counter clockwise order as viewd from the outside)
      double P0[3] = {0.0, 0.0, 0.0};
      double P1[3] = {1.0, 0.0, 0.0};
      double P2[3] = {1.0, 1.0, 0.0};
      double P3[3] = {0.0, 1.0, 0.0};
      double P4[3] = {0.0, 0.0, 1.0};
      double P5[3] = {1.0, 0.0, 1.0};
      double P6[3] = {1.0, 1.0, 1.0};
      double P7[3] = {0.0, 1.0, 1.0};

      // Create the points
      vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(P0);
      points->InsertNextPoint(P1);
      points->InsertNextPoint(P2);
      points->InsertNextPoint(P3);
      points->InsertNextPoint(P4);
      points->InsertNextPoint(P5);
      points->InsertNextPoint(P6);
      points->InsertNextPoint(P7);

      // Create a hexahedron from the points
      vtkSmartPointer<vtkHexahedron> hex =
        vtkSmartPointer<vtkHexahedron>::New();
      hex->GetPointIds()->SetId(0,0);
      hex->GetPointIds()->SetId(1,1);
      hex->GetPointIds()->SetId(2,2);
      hex->GetPointIds()->SetId(3,3);
      hex->GetPointIds()->SetId(4,4);
      hex->GetPointIds()->SetId(5,5);
      hex->GetPointIds()->SetId(6,6);
      hex->GetPointIds()->SetId(7,7);

      // Add the hexahedron to a cell array
      vtkSmartPointer<vtkCellArray> hexs =
        vtkSmartPointer<vtkCellArray>::New();
      hexs->InsertNextCell(hex);

      // Add the points and hexahedron to an unstructured grid
      vtkSmartPointer<vtkUnstructuredGrid> uGrid =
        vtkSmartPointer<vtkUnstructuredGrid>::New();
      uGrid->SetPoints(points);
      uGrid->InsertNextCell(hex->GetCellType(), hex->GetPointIds());

      // Visualize
      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
    #if VTK_MAJOR_VERSION <= 5
      mapper->SetInputConnection(uGrid->GetProducerPort());
    #else
      mapper->SetInputData(uGrid);
    #endif

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

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      renderer->AddActor(actor);
      renderer->SetBackground(.2, .3, .4);

      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(Hexahedron)

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

    add_executable(Hexahedron MACOSX_BUNDLE Hexahedron.cxx )

    target_link_libraries(Hexahedron ${VTK_LIBRARIES})

### Download and Build Hexahedron

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

    cd Hexahedron/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:

    ./Hexahedron

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.