# IntermixedUnstructuredGrid

VTKExamples/Cxx/VolumeRendering/IntermixedUnstructuredGrid

### Code

IntermixedUnstructuredGrid.cxx

    /* converted from:
     *
    https://github.com/Kitware/VTK/blob/49fbbe479dfdf47c86c02d6cae48c41b9c844b04/Examples/VolumeRendering/Tcl/IntermixedUnstructuredGrid.tcl
    *
    */

    #include <vtkActor.h>
    #include <vtkColorTransferFunction.h>
    #include <vtkContourFilter.h>
    #include <vtkDataSetTriangleFilter.h>
    #include <vtkPiecewiseFunction.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSLCReader.h>
    #include <vtkSmartPointer.h>
    #include <vtkStructuredPointsReader.h>
    #include <vtkThreshold.h>
    #include <vtkUnstructuredGridVolumeRayCastMapper.h>
    #include <vtkVolumeProperty.h>

    int main(int argc, char *argv[])
    {
      if (argc < 3)
        {
        std::cerr << "Usage: " << argv[0] << " file.vtk file.slc" << std::endl;
        return EXIT_FAILURE;
        }

      // Create the reader for the data
      // This is the data the will be volume rendered
      vtkSmartPointer<vtkStructuredPointsReader> reader =
        vtkSmartPointer<vtkStructuredPointsReader>::New();
      reader->SetFileName(argv[1]);

      // create a reader for the other data that will
      // be contoured and displayed as a polygonal mesh
      vtkSmartPointer<vtkSLCReader> reader2 =
        vtkSmartPointer<vtkSLCReader>::New();
      reader2->SetFileName(argv[2]);

      // convert from vtkImageData to vtkUnstructuredGrid, remove
      // any cells where all values are below 80
      vtkSmartPointer<vtkThreshold> thresh =
        vtkSmartPointer<vtkThreshold>::New();
      thresh->ThresholdByUpper(80);
      thresh->AllScalarsOff();
      thresh->SetInputConnection(reader->GetOutputPort());

      vtkSmartPointer<vtkDataSetTriangleFilter> trifilter =
        vtkSmartPointer<vtkDataSetTriangleFilter>::New();
      trifilter->SetInputConnection(thresh->GetOutputPort());

      // Create transfer mapping scalar value to opacity
      vtkSmartPointer<vtkPiecewiseFunction> opacityTransferFunction =
        vtkSmartPointer<vtkPiecewiseFunction>::New();
      opacityTransferFunction->AddPoint(80,  0.0);
      opacityTransferFunction->AddPoint(120, 0.2);
      opacityTransferFunction->AddPoint(255, 0.2);

      // Create transfer mapping scalar value to color
      vtkSmartPointer<vtkColorTransferFunction> colorTransferFunction =
        vtkSmartPointer<vtkColorTransferFunction>::New();
      colorTransferFunction->AddRGBPoint( 80.0,0.0,0.0,0.0);
      colorTransferFunction->AddRGBPoint(120.0,0.0,0.0,1.0);
      colorTransferFunction->AddRGBPoint(160.0,1.0,0.0,0.0);
      colorTransferFunction->AddRGBPoint(200.0,0.0,1.0,0.0);
      colorTransferFunction->AddRGBPoint(255.0,0.0,1.0,1.0);

      // The property describes how the data will look
      vtkSmartPointer<vtkVolumeProperty> volumeProperty =
        vtkSmartPointer<vtkVolumeProperty>::New();
      volumeProperty->SetColor(colorTransferFunction);
      volumeProperty->SetScalarOpacity(opacityTransferFunction);
      volumeProperty->ShadeOff();
      volumeProperty->SetInterpolationTypeToLinear();

      // The mapper / ray cast function know how to render the data
      vtkSmartPointer<vtkUnstructuredGridVolumeRayCastMapper> volumeMapper =
        vtkSmartPointer<vtkUnstructuredGridVolumeRayCastMapper>::New();
      volumeMapper->SetInputConnection(trifilter->GetOutputPort());

      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->SetSize(640,512);
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();

      // contour the second dataset
      vtkSmartPointer<vtkContourFilter> contour =
        vtkSmartPointer<vtkContourFilter>::New();
      contour->SetValue(0, 80);
      contour->SetInputConnection(reader2->GetOutputPort());

      // create a mapper for the polygonal data
      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(contour->GetOutputPort());
      mapper->ScalarVisibilityOff();

      // create an actor for the polygonal data
      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      ren1->AddViewProp(actor);

      ren1->SetBackground(0.1,0.4,0.2);

      renWin->AddRenderer(ren1);

      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      vtkSmartPointer<vtkVolume> volume =
        vtkSmartPointer<vtkVolume>::New();
      volume->SetMapper(volumeMapper);
      volume->SetProperty(volumeProperty);

      ren1->AddVolume(volume);

      ren1->ResetCamera();

      // Render composite. In default mode. For coverage.
      renWin->Render();

      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(IntermixedUnstructuredGrid)

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

    add_executable(IntermixedUnstructuredGrid MACOSX_BUNDLE IntermixedUnstructuredGrid.cxx )

    target_link_libraries(IntermixedUnstructuredGrid ${VTK_LIBRARIES})

### Download and Build IntermixedUnstructuredGrid

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

    cd IntermixedUnstructuredGrid/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:

    ./IntermixedUnstructuredGrid

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.