# Delaunay3DDemo

VTKExamples/Cxx/Modelling/Delaunay3DDemo

### Description

This example creates a tetrahedral mesh from unorganized points. The example uses the vtkDelaunay3D filter. The resulting mesh will be a solid convex hull of the original points. The example takes the points from a XML PolyData file (.vtp) produces the 3D Delaunay tetrahedralization (both with alpha = 0 and a non-zero alpha), and displays the result on the screen.

For alpha != 0 (right window), the tetra are yellow, the lines are blue and the triangles are red.

Alpha can be changed interactively to see its affect on the resulting surface.

### Code

Delaunay3DDemo.cxx

    #include <vtkDelaunay3D.h>
    #include <vtkSmartPointer.h>

    #include <vtkCellArray.h>
    #include <vtkProperty.h>
    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkPoints.h>
    #include <vtkPolyData.h>
    #include <vtkPolygon.h>
    #include <vtkMath.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkCleanPolyData.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkCellIterator.h>
    #include <vtkCellData.h>
    #include <vtkUnsignedCharArray.h>
    #include <vtkNamedColors.h>

    #include <vtkTextProperty.h>
    #include <vtkTextMapper.h>
    #include <vtkActor2D.h>

    #include <vtkCommand.h>
    #include <vtkSliderWidget.h>
    #include <vtkSliderRepresentation2D.h>

    #include <sstream>

    #include <vtksys/SystemTools.hxx>
    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkSphereSource.h>

    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName);
    }
    namespace
    {
    void MakeWidget(vtkSmartPointer<vtkSliderWidget> &,
                    vtkSmartPointer<vtkDelaunay3D> &,
                    vtkSmartPointer<vtkTextMapper> &,
                    vtkSmartPointer<vtkRenderer> &,
                    vtkSmartPointer<vtkRenderWindowInteractor> &);
    }

    int main ( int argc, char *argv[] )
    {
      if(argc < 2)
      {
        std::cout << "Usage: " << argv[0]
                  << " filename.vtp" << std::endl;
        return EXIT_FAILURE;
      }

      vtkSmartPointer<vtkPolyData> polyData = ReadPolyData(argc > 1 ? argv[1] : "");

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

      vtkSmartPointer<vtkDataSetMapper> originalMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      originalMapper->SetInputData(polyData);
      originalMapper->ScalarVisibilityOff();
      originalMapper->SetScalarModeToUseCellData();

      vtkSmartPointer<vtkActor> originalActor =
        vtkSmartPointer<vtkActor>::New();
      originalActor->SetMapper(originalMapper);
      originalActor->GetProperty()->SetColor(color->GetColor3d("tomato").GetData());
      originalActor->GetProperty()->SetInterpolationToFlat();

      // Clean the polydata. This will remove duplicate points that may be
      // present in the input data.
      vtkSmartPointer<vtkCleanPolyData> cleaner =
        vtkSmartPointer<vtkCleanPolyData>::New();
      cleaner->SetInputData (polyData);

      // Generate a tetrahedral mesh from the input points. By
      // default, the generated volume is the convex hull of the points.
      vtkSmartPointer<vtkDelaunay3D> delaunay3D =
        vtkSmartPointer<vtkDelaunay3D>::New();
      delaunay3D->SetInputConnection (cleaner->GetOutputPort());

      vtkSmartPointer<vtkDataSetMapper> delaunayMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      delaunayMapper->SetInputConnection(delaunay3D->GetOutputPort());
      delaunayMapper->SetScalarModeToUseCellData();

      vtkSmartPointer<vtkActor> delaunayActor =
        vtkSmartPointer<vtkActor>::New();
      delaunayActor->SetMapper(delaunayMapper);
      delaunayActor->GetProperty()->SetColor(color->GetColor3d("banana").GetData());
      delaunayActor->GetProperty()->SetInterpolationToFlat();

      // Generate a mesh from the input points. If Alpha is non-zero, then
      // tetrahedra, triangles, edges and vertices that lie within the
      // alpha radius are output.
      vtkSmartPointer<vtkDelaunay3D> delaunay3DAlpha =
        vtkSmartPointer<vtkDelaunay3D>::New();
      delaunay3DAlpha->SetInputConnection (cleaner->GetOutputPort());
      delaunay3DAlpha->SetAlpha(.5);
      delaunay3DAlpha->Update();

      vtkSmartPointer<vtkUnsignedCharArray> cellData =
        vtkSmartPointer<vtkUnsignedCharArray>::New();
      cellData->SetNumberOfComponents(3);

      int numTetras = 0;
      int numLines = 0;
      int numTris = 0;
      int numVerts = 0;

      vtkCellIterator *it = delaunay3DAlpha->GetOutput()->NewCellIterator();
      for (it->InitTraversal(); !it->IsDoneWithTraversal(); it->GoToNextCell())
      {
        if (it->GetCellType() == VTK_TETRA)
        {
          numTetras++;
          cellData->InsertNextTypedTuple(color->GetColor3ub("Banana").GetData());
        }
        else if (it->GetCellType() == VTK_LINE)
        {
          numLines++;
          cellData->InsertNextTypedTuple(color->GetColor3ub("Peacock").GetData());
        }
        else if (it->GetCellType() == VTK_TRIANGLE)
        {
          numTris++;
          cellData->InsertNextTypedTuple(color->GetColor3ub("Tomato").GetData());
        }
        else if (it->GetCellType() == VTK_VERTEX)
        {
          numVerts++;
          cellData->InsertNextTypedTuple(color->GetColor3ub("Lime").GetData());
        }
      }
      it->Delete();

      std::stringstream ss;
      ss << "numTetras: " << numTetras << std::endl;
      ss << "numLines: " << numLines << std::endl;
      ss << "numTris: " << numTris << std::endl;
      ss << "numVerts: " << numVerts;

      // Set the cell color depending on cell type
      delaunay3DAlpha->GetOutput()->GetCellData()->SetScalars(cellData);

      vtkSmartPointer<vtkDataSetMapper> delaunayAlphaMapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      delaunayAlphaMapper->SetInputConnection(delaunay3DAlpha->GetOutputPort());
      delaunayAlphaMapper->SetScalarModeToUseCellData();

      vtkSmartPointer<vtkActor> delaunayAlphaActor =
        vtkSmartPointer<vtkActor>::New();
      delaunayAlphaActor->SetMapper(delaunayAlphaMapper);
      delaunayAlphaActor->GetProperty()->SetPointSize(5.0);
      delaunayAlphaActor->GetProperty()->SetInterpolationToFlat();

      // Visualize

      vtkSmartPointer<vtkTextProperty> textProperty =
        vtkSmartPointer<vtkTextProperty>::New();
      textProperty->SetFontSize(16);
      textProperty->SetColor(color->GetColor3d("Black").GetData());

      vtkSmartPointer<vtkTextMapper> textMapper =
        vtkSmartPointer<vtkTextMapper>::New();
      textMapper->SetInput(ss.str().c_str());
      textMapper->SetTextProperty(textProperty);

      vtkSmartPointer<vtkActor2D> textActor =
        vtkSmartPointer<vtkActor2D>::New();
      textActor->SetMapper(textMapper);
      textActor->SetPosition(10, 10);

      // Define viewport ranges
      // (xmin, ymin, xmax, ymax)
      double leftViewport[4] = {0.0, 0.0, 0.33, 1.0};
      double centerViewport[4] = {0.33, 0.0, 0.66, 1.0};
      double rightViewport[4] = {0.66, 0.0, 1.0, 1.0};

      // Shared camera
      vtkSmartPointer<vtkCamera> sharedCamera =
        vtkSmartPointer<vtkCamera>::New();

      // Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> originalRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      originalRenderer->SetActiveCamera(sharedCamera);

      vtkSmartPointer<vtkRenderer> delaunayRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      delaunayRenderer->SetActiveCamera(sharedCamera);

      vtkSmartPointer<vtkRenderer> delaunayAlphaRenderer =
        vtkSmartPointer<vtkRenderer>::New();
      delaunayAlphaRenderer->SetActiveCamera(sharedCamera);

      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(900,300);

      renderWindow->AddRenderer(originalRenderer);
      originalRenderer->SetViewport(leftViewport);
      renderWindow->AddRenderer(delaunayRenderer);
      delaunayRenderer->SetViewport(centerViewport);
      renderWindow->AddRenderer(delaunayAlphaRenderer);
      delaunayAlphaRenderer->SetViewport(rightViewport);

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

      vtkSmartPointer<vtkSliderWidget> widget =
        vtkSmartPointer<vtkSliderWidget>::New();
      MakeWidget(widget, delaunay3DAlpha, textMapper, delaunayAlphaRenderer, renderWindowInteractor);

      originalRenderer->AddActor(originalActor);
      delaunayRenderer->AddActor(delaunayActor);
      delaunayAlphaRenderer->AddActor(delaunayAlphaActor);
      delaunayAlphaRenderer->AddViewProp(textActor);

      originalRenderer->SetBackground(
        color->GetColor3d("Slate_Grey").GetData());
      delaunayRenderer->SetBackground(
        color->GetColor3d("Light_Grey").GetData());
      delaunayAlphaRenderer->SetBackground(
        color->GetColor3d("Grey").GetData());

      originalRenderer->ResetCamera();
      renderWindow->Render();

      // Render and interact
      renderWindowInteractor->Start();
      return EXIT_SUCCESS;
    }

    namespace
    {
    // These callbacks do the actual work.
    // Callbacks for the interactions
    class SliderCallbackAlpha : public vtkCommand
    {
    public:
      static SliderCallbackAlpha *New()
      {
        return new SliderCallbackAlpha;
      }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkSliderWidget *sliderWidget =
          reinterpret_cast<vtkSliderWidget*>(caller);
        double value = static_cast<vtkSliderRepresentation2D *>(sliderWidget->GetRepresentation())->GetValue();
        this->Delaunay3D->SetAlpha(value);
        this->Delaunay3D->Update();

        vtkSmartPointer<vtkUnsignedCharArray> cellData =
          vtkSmartPointer<vtkUnsignedCharArray>::New();
        cellData->SetNumberOfComponents(3);

        // Set the cell color depending on cell type
        vtkSmartPointer<vtkNamedColors> color =
          vtkSmartPointer<vtkNamedColors>::New();
        int numTetras = 0;
        int numLines = 0;
        int numTris = 0;
        int numVerts = 0;

        vtkCellIterator *it = this->Delaunay3D->GetOutput()->NewCellIterator();
        for (it->InitTraversal(); !it->IsDoneWithTraversal(); it->GoToNextCell())
        {
          if (it->GetCellType() == VTK_TETRA)
          {
            numTetras++;
            cellData->InsertNextTypedTuple(color->GetColor3ub("Banana").GetData());
          }
          else if (it->GetCellType() == VTK_LINE)
          {
            numLines++;
            cellData->InsertNextTypedTuple(color->GetColor3ub("Peacock").GetData());
          }
          else if (it->GetCellType() == VTK_TRIANGLE)
          {
            numTris++;
            cellData->InsertNextTypedTuple(color->GetColor3ub("Tomato").GetData());
          }
          else if (it->GetCellType() == VTK_VERTEX)
          {
            numVerts++;
            cellData->InsertNextTypedTuple(color->GetColor3ub("Lime").GetData());
          }
        }
        it->Delete();
        this->Delaunay3D->GetOutput()->GetCellData()->SetScalars(cellData);
        std::stringstream ss;
        ss << "numTetras: " << numTetras << std::endl;
        ss << "numLines: " << numLines << std::endl;
        ss << "numTris: " << numTris << std::endl;
        ss << "numVerts: " << numVerts;
        this->TextMapper->SetInput(ss.str().c_str());

      }
      SliderCallbackAlpha():Delaunay3D(0),TextMapper(0) {}
      vtkDelaunay3D *Delaunay3D;
      vtkTextMapper *TextMapper;
    };

    void
    MakeWidget(vtkSmartPointer<vtkSliderWidget> &widget,
               vtkSmartPointer<vtkDelaunay3D> &delaunay3D,
               vtkSmartPointer<vtkTextMapper> &textMapper,
               vtkSmartPointer<vtkRenderer> &renderer,
               vtkSmartPointer<vtkRenderWindowInteractor> &interactor)
    {
      // Setup a slider widget for each varying parameter
      double tubeWidth(.02);
      double sliderLength(.04);
      double titleHeight(.04);
      double labelHeight(.04);

      vtkSmartPointer<vtkSliderRepresentation2D> sliderRepAlpha =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();

      sliderRepAlpha->SetRenderer(renderer);

      sliderRepAlpha->SetMinimumValue(0.0001);
      sliderRepAlpha->SetMaximumValue(1.0);
      sliderRepAlpha->SetValue(delaunay3D->GetAlpha());
      sliderRepAlpha->SetTitleText("Alpha");
      sliderRepAlpha->SetRenderer(renderer);
      sliderRepAlpha->GetPoint1Coordinate()->SetValue(0.1, .1);
      sliderRepAlpha->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedViewport();
      sliderRepAlpha->GetPoint2Coordinate()->SetValue(.9, .1);
      sliderRepAlpha->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedViewport();

      sliderRepAlpha->SetTubeWidth(tubeWidth);
      sliderRepAlpha->SetSliderLength(sliderLength);
      sliderRepAlpha->SetTitleHeight(titleHeight);
      sliderRepAlpha->SetLabelHeight(labelHeight);
      sliderRepAlpha->SetEndCapLength(tubeWidth*1.5);
      sliderRepAlpha->SetSliderWidth(tubeWidth*1.5);
      sliderRepAlpha->BuildRepresentation();

      widget->SetRepresentation(sliderRepAlpha);
      widget->SetAnimationModeToAnimate();
      widget->SetNumberOfAnimationSteps(2);
      widget->SetInteractor(interactor);
      widget->EnabledOn();

      vtkSmartPointer<SliderCallbackAlpha> callbackAlpha =
        vtkSmartPointer<SliderCallbackAlpha>::New();
      callbackAlpha->Delaunay3D = delaunay3D;
      callbackAlpha->TextMapper = textMapper;

      widget->AddObserver(vtkCommand::InteractionEvent,callbackAlpha);
    }
    }
    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName)
    {
      vtkSmartPointer<vtkPolyData> polyData;
      std::string extension = vtksys::SystemTools::GetFilenameExtension(std::string(fileName));
      if (extension == ".ply")
      {
        vtkSmartPointer<vtkPLYReader> reader =
          vtkSmartPointer<vtkPLYReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtp")
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".obj")
      {
        vtkSmartPointer<vtkOBJReader> reader =
          vtkSmartPointer<vtkOBJReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".stl")
      {
        vtkSmartPointer<vtkSTLReader> reader =
          vtkSmartPointer<vtkSTLReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtk")
      {
        vtkSmartPointer<vtkPolyDataReader> reader =
          vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".g")
      {
        vtkSmartPointer<vtkBYUReader> reader =
          vtkSmartPointer<vtkBYUReader>::New();
        reader->SetGeometryFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> source =
          vtkSmartPointer<vtkSphereSource>::New();
        source->Update();
        polyData = source->GetOutput();
      }
      return polyData;
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(Delaunay3DDemo)

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

    add_executable(Delaunay3DDemo MACOSX_BUNDLE Delaunay3DDemo.cxx )

    target_link_libraries(Delaunay3DDemo ${VTK_LIBRARIES})

### Download and Build Delaunay3DDemo

Click here to download Delaunay3DDemo and its CMakeLists.txt file. Once the tarball Delaunay3DDemo.tar has been downloaded and extracted,

    cd Delaunay3DDemo/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:

    ./Delaunay3DDemo

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.