# PolyDataToUnstructuredGrid

VTKExamples/Cxx/PolyData/PolyDataToUnstructuredGrid

### Description

There is not a filter whose sole purpose is converting a vtkPolyData to a vtkUnstructuredGrid. However, the append filter can accept any type of input, and produces a vtkUnstructuredGrid, so we can use it for this purpose.

### Code

PolyDataToUnstructuredGrid.cxx

    #include <vtkAppendFilter.h>
    #include <vtkPolyData.h>
    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkVersion.h>
    #include <vtkXMLUnstructuredGridWriter.h>

    int main(int, char *[])
    {
      // Create a sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(0.0, 0.0, 0.0);
      sphereSource->SetRadius(5.0);
      sphereSource->Update();

      // Combine the two data sets
      vtkSmartPointer<vtkAppendFilter> appendFilter =
        vtkSmartPointer<vtkAppendFilter>::New();
    #if VTK_MAJOR_VERSION <= 5
      appendFilter->AddInput(sphereSource->GetOutput());
    #else
      appendFilter->AddInputData(sphereSource->GetOutput());
    #endif
      appendFilter->Update();

      vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid =
         vtkSmartPointer<vtkUnstructuredGrid>::New();
      unstructuredGrid->ShallowCopy(appendFilter->GetOutput());

      // Write the unstructured grid
      vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
        vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
      writer->SetFileName("UnstructuredGrid.vtu");
      #if VTK_MAJOR_VERSION <= 5
        writer->SetInput(unstructuredGrid);
      #else
        writer->SetInputData(unstructuredGrid);
      #endif
      writer->Write();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(PolyDataToUnstructuredGrid)

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

    add_executable(PolyDataToUnstructuredGrid MACOSX_BUNDLE PolyDataToUnstructuredGrid.cxx )

    target_link_libraries(PolyDataToUnstructuredGrid ${VTK_LIBRARIES})

### Download and Build PolyDataToUnstructuredGrid

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

    cd PolyDataToUnstructuredGrid/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:

    ./PolyDataToUnstructuredGrid

WINDOWS USERS

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