# PlatonicSolids

VTKExamples/Cxx/GeometricObjects/PlatonicSolids

### Description

Display all five Platonic solids in a grid.

Platonic solids are regular, convex polyhedrons. They are constructed by congruent (identical in shape and size) regular (all angles equal and all sides equal) polygonal faces with the same number of faces meeting at each vertex.

Five solids satisfy the above criteria:

Figure | Tetrahedron | Cube | Octahedron | Icosahedron | Dodecahedron
--- | --- | --- | --- | --- | ---
Vertices | 4 | 8 | 6 (2 × 3) | 12 (4 × 3) | 20 (8 + 4 × 3)
Edges | 6 | 12 | 12 | 30 | 30
Faces | 4 | 6 | 8 | 20 | 12

The relationship between vertices, edges and faces is given by Euler's formula:

    V - E + F = 2

Other Languages

See (Python)

### Code

PlatonicSolids.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkLookupTable.h>
    #include <vtkNamedColors.h>
    #include <vtkPlatonicSolidSource.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSmartPointer.h>
    #include <vtkTextActor.h>
    #include <vtkTextMapper.h>
    #include <vtkTextProperty.h>

    #include <string>
    #include <vector>

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

      // Each face has a different cell scalar
      // Here we create a lookup table with a different colour
      // for each face. The colors have been carefully
      // chosen so that adjacent cells are colored distinctly.
      vtkSmartPointer<vtkLookupTable> lut =
        vtkSmartPointer<vtkLookupTable>::New();
      lut->SetNumberOfTableValues(20);
      lut->SetTableRange(0.0, 19.0);
      lut->Build();
      lut->SetTableValue(0, 0.1, 0.1, 0.1);
      lut->SetTableValue(1, 0, 0, 1);
      lut->SetTableValue(2, 0, 1, 0);
      lut->SetTableValue(3, 0, 1, 1);
      lut->SetTableValue(4, 1, 0, 0);
      lut->SetTableValue(5, 1, 0, 1);
      lut->SetTableValue(6, 1, 1, 0);
      lut->SetTableValue(7, 0.9, 0.7, 0.9);
      lut->SetTableValue(8, 0.5, 0.5, 0.5);
      lut->SetTableValue(9, 0.0, 0.0, 0.7);
      lut->SetTableValue(10, 0.5, 0.7, 0.5);
      lut->SetTableValue(11, 0, 0.7, 0.7);
      lut->SetTableValue(12, 0.7, 0, 0);
      lut->SetTableValue(13, 0.7, 0, 0.7);
      lut->SetTableValue(14, 0.7, 0.7, 0);
      lut->SetTableValue(15, 0, 0, 0.4);
      lut->SetTableValue(16, 0, 0.4, 0);
      lut->SetTableValue(17, 0, 0.4, 0.4);
      lut->SetTableValue(18, 0.4, 0, 0);
      lut->SetTableValue(19, 0.4, 0, 0.4);

      std::vector<vtkSmartPointer<vtkPolyDataMapper>> mappers;
      std::vector<vtkSmartPointer<vtkActor>> actors;
      std::vector<vtkSmartPointer<vtkTextMapper>> textMappers;
      std::vector<vtkSmartPointer<vtkActor2D>> textActors;
      std::vector<vtkSmartPointer<vtkRenderer>> renderers;

      // Create a common text property.
      vtkSmartPointer<vtkTextProperty> textProperty =
        vtkSmartPointer<vtkTextProperty>::New();
      textProperty->SetFontSize(16);
      textProperty->SetJustificationToCentered();

      // Create the render window and interactor.
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->SetWindowName("Platonic Solids");
      vtkSmartPointer<vtkRenderWindowInteractor> iRen =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iRen->SetRenderWindow(renWin);

      // There are five platonic solids.
      std::vector<std::string> names{"Tetrahedron", "Cube", "Octahedron",
                                     "Icosahedron", "Dodecahedron"};
      std::vector<vtkSmartPointer<vtkPlatonicSolidSource>> PlatonicSolids;
      for (auto i = 0; i < names.size(); ++i)
      {
        PlatonicSolids.push_back(vtkSmartPointer<vtkPlatonicSolidSource>::New());
        PlatonicSolids[i]->SetSolidType(i);

        mappers.push_back(vtkSmartPointer<vtkPolyDataMapper>::New());
        mappers[i]->SetInputConnection(PlatonicSolids[i]->GetOutputPort());
        mappers[i]->SetLookupTable(lut);
        mappers[i]->SetScalarRange(0, 19);

        actors.push_back(vtkSmartPointer<vtkActor>::New());
        actors[i]->SetMapper(mappers[i]);

        textMappers.push_back(vtkSmartPointer<vtkTextMapper>::New());
        textMappers[i]->SetInput(names[i].c_str());
        textMappers[i]->SetTextProperty(textProperty);

        textActors.push_back(vtkSmartPointer<vtkActor2D>::New());
        textActors[i]->SetMapper(textMappers[i]);
        textActors[i]->SetPosition(120, 16);

        renderers.push_back(vtkSmartPointer<vtkRenderer>::New());
        renderers[i]->AddActor(actors[i]);
        renderers[i]->AddViewProp(textActors[i]);

        renWin->AddRenderer(renderers[i]);
      }

      // Setup the viewports
      auto xGridDimensions = 3;
      auto yGridDimensions = 2;
      auto rendererSize = 300;
      renWin->SetSize(rendererSize * xGridDimensions,
                      rendererSize * yGridDimensions);
      for (auto row = 0; row < yGridDimensions; ++row)
      {
        for (auto col = 0; col < xGridDimensions; ++col)
        {
          auto index = row * xGridDimensions + col;

          // (xmin, ymin, xmax, ymax)
          double viewport[4] = {
            static_cast<double>(col) / xGridDimensions,
            static_cast<double>(yGridDimensions - (row + 1)) / yGridDimensions,
            static_cast<double>(col + 1) / xGridDimensions,
            static_cast<double>(yGridDimensions - row) / yGridDimensions};
          if (index > (actors.size() - 1))
          {
            // Add a renderer even if there is no actor.
            // This makes the render window background all the same color.
            vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
            ren->SetBackground(colors->GetColor3d("SlateGray").GetData());
            ren->SetViewport(viewport);
            renWin->AddRenderer(ren);
            continue;
          }

          renderers[index]->SetViewport(viewport);
          renderers[index]->SetBackground(
            colors->GetColor3d("SlateGray").GetData());
          renderers[index]->ResetCamera();
          renderers[index]->GetActiveCamera()->Azimuth(4.5);
          renderers[index]->GetActiveCamera()->Elevation(-18);
          renderers[index]->ResetCameraClippingRange();
        }
      }

      iRen->Initialize();
      renWin->Render();
      iRen->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(PlatonicSolids)

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

### Download and Build PlatonicSolids

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

    cd PlatonicSolids/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:

    ./PlatonicSolids

WINDOWS USERS

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