# Motor

VTKExamples/Cxx/VisualizationAlgorithms/Motor

### Description

This is an example of texture clipping using a transparent texture map. The motor shown consists of five complex parts, some of which are hidden by the outer casing. To see the inside of the motor, we define an implicit clipping function. This function is simply the intersection of two planes to form a clipping "corner". The object * vtkImplicitTextureCoords** is used in combination with this implicit function to generate texture coordinates. These objects are then rendered with the appropriate texture map and the internal parts of the motor can be seen.

The texture map consists of three regions (as described previously in the chapter). The concealed region is transparent. The transition region is opaque but with a black (zero intensity) color. The highlighted region is full intensity and opaque. As can be seen from the result , the boundaries appear as black borders giving a nice visual effect.

Note the use of vectors in the C++ version and lists in the Python version to reduce repetitious code.

Info

See Figure 9-53 in Chapter 9 The VTK Textbook.

Other Languages

See (Python)

### Code

Motor.cxx

    /*
    This code is based on the VTK file: /IO/Geometry/Testing/Python/motor.py.
    */

    #include <vtkActor.h>
    #include <vtkBYUReader.h>
    #include <vtkCamera.h>
    #include <vtkDataSetMapper.h>
    #include <vtkFloatArray.h>
    #include <vtkImplicitTextureCoords.h>
    #include <vtkNamedColors.h>
    #include <vtkPlanes.h>
    #include <vtkPoints.h>
    #include <vtkPolyDataNormals.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkStructuredPointsReader.h>
    #include <vtkTexture.h>

    #include <string>
    #include <vector>

    int main(int argc, char* argv[])
    {
      if (argc < 3)
      {
        std::cout << "Usage: " << argv[0] << " textureFile motorFile" << std::endl;
        std::cout << "where: textureFile is the texture file: texThres2.vtk."
                  << std::endl;
        std::cout << "       motorFile is ihe motor file: motor.g." << std::endl;
        return EXIT_FAILURE;
      }

      std::string textureFile = argv[1];
      std::string motorFile = argv[2];

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      // Create the Renderer, RenderWindow and RenderWindowInteractor.
      vtkSmartPointer<vtkRenderer> ren = vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren);
      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      // Create the cutting planes.
      vtkSmartPointer<vtkPlanes> planes = vtkSmartPointer<vtkPlanes>::New();
      vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
      vtkSmartPointer<vtkFloatArray> norms = vtkSmartPointer<vtkFloatArray>::New();

      norms->SetNumberOfComponents(3);
      points->InsertPoint(0, 0.0, 0.0, 0.0);
      norms->InsertTuple3(0, 0.0, 0.0, 1.0);
      points->InsertPoint(1, 0.0, 0.0, 0.0);
      norms->InsertTuple3(1, -1.0, 0.0, 0.0);
      planes->SetPoints(points);
      planes->SetNormals(norms);

      // Get the texture.
      vtkSmartPointer<vtkStructuredPointsReader> texReader =
        vtkSmartPointer<vtkStructuredPointsReader>::New();
      texReader->SetFileName(textureFile.c_str());
      vtkSmartPointer<vtkTexture> texture = vtkSmartPointer<vtkTexture>::New();
      texture->SetInputConnection(texReader->GetOutputPort());
      texture->InterpolateOff();
      texture->RepeatOff();

      // Set up the pipelines for the parts of the motor.
      // We will use lists of pipeline objects.
      auto numberOfParts = 5;
      std::vector<vtkSmartPointer<vtkBYUReader>> byu;
      std::vector<vtkSmartPointer<vtkPolyDataNormals>> normals;
      std::vector<vtkSmartPointer<vtkImplicitTextureCoords>> tex;
      std::vector<vtkSmartPointer<vtkDataSetMapper>> byuMapper;
      std::vector<vtkSmartPointer<vtkActor>> byuActor;
      std::vector<std::string> partColours{"cold_grey", "peacock", "raw_sienna",
                                           "banana", "peach_puff"};
      // Use this to control which parts to display.
      std::vector<bool> displayParts(numberOfParts, true);
      // If displayParts[2] = false; then an image like that in the VTK tests is
      // produced.

      for (auto i = 0; i < numberOfParts; ++i)
      {
        byu.push_back(vtkSmartPointer<vtkBYUReader>::New());
        byu[i]->SetGeometryFileName(motorFile.c_str());
        byu[i]->SetPartNumber(i + 1);

        normals.push_back(vtkSmartPointer<vtkPolyDataNormals>::New());
        normals[i]->SetInputConnection(byu[i]->GetOutputPort());

        tex.push_back(vtkSmartPointer<vtkImplicitTextureCoords>::New());
        tex[i]->SetInputConnection(normals[i]->GetOutputPort());
        tex[i]->SetRFunction(planes);
        // tex[i]->FlipTextureOn();

        byuMapper.push_back(vtkSmartPointer<vtkDataSetMapper>::New());
        byuMapper[i]->SetInputConnection(tex[i]->GetOutputPort());

        byuActor.push_back(vtkSmartPointer<vtkActor>::New());
        byuActor[i]->SetMapper(byuMapper[i]);
        byuActor[i]->SetTexture(texture);
        byuActor[i]->GetProperty()->SetColor(
          colors->GetColor3d(partColours[i]).GetData());

        ren->AddActor(byuActor[i]);
        if (displayParts[i])
        {
          byuActor[i]->VisibilityOn();
        }
        else
        {
          byuActor[i]->VisibilityOff();
        }
      }

      ren->SetBackground(colors->GetColor3d("AliceBlue").GetData());

      renWin->SetSize(512, 512);

      vtkSmartPointer<vtkCamera> camera = vtkSmartPointer<vtkCamera>::New();
      camera->SetFocalPoint(0.0286334, 0.0362996, 0.0379685);
      camera->SetPosition(1.37067, 1.08629, -1.30349);
      camera->SetViewAngle(17.673);
      camera->SetClippingRange(1, 10);
      camera->SetViewUp(-0.376306, -0.5085, -0.774482);
      ren->SetActiveCamera(camera);

      // Render the image.
      renWin->Render();
      iren->Initialize();
      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(Motor)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersCore
      vtkFiltersTexture
      vtkIOGeometry
      vtkIOLegacy
      vtkInteractionStyle
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping Motor: ${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(Motor MACOSX_BUNDLE Motor.cxx )
      target_link_libraries(Motor PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(Motor MACOSX_BUNDLE Motor.cxx )
      target_link_libraries(Motor PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS Motor
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build Motor

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

    cd Motor/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:

    ./Motor

WINDOWS USERS

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