# HAVSVolumeMapper

VTKExamples/Cxx/VolumeRendering/HAVSVolumeMapper

### Code

HAVSVolumeMapper.cxx

    #include <vtkSmartPointer.h>
    #include <vtkHAVSVolumeMapper.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkStructuredPointsReader.h>
    #include <vtkSLCReader.h>
    #include <vtkStructuredPoints.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkThreshold.h>
    #include <vtkDataSetTriangleFilter.h>
    #include <vtkPiecewiseFunction.h>
    #include <vtkColorTransferFunction.h>
    #include <vtkVolumeProperty.h>
    #include <vtkVolume.h>
    #include <vtkContourFilter.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkStdString.h>
    #include <vtkTextActor.h>
    #include <vtkTextProperty.h>

    int main(int argc, char*argv[])
    {
      if(argc < 3)
      {
        std::cerr << "Required arguments: volumeVTKFile contourVTKFile" << std::endl;
        return EXIT_FAILURE;
      }

      // This is the data that will be volume rendered.
      std::string volumeFilename = argv[1]; // "/Data/ironProt.vtk";

      // Create a reader for the other data that will be contoured and
      // displayed as a polygonal mesh.
      std::string contourFilename = argv[2]; // "/Data/neghip.slc";

      // Create the standard renderer, render window, and interactor.
      vtkSmartPointer<vtkRenderer> ren1 =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(ren1);
      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);
      iren->SetDesiredUpdateRate(3);

      // Create the reader for the data.
      vtkSmartPointer<vtkStructuredPointsReader> reader =
        vtkSmartPointer<vtkStructuredPointsReader>::New();
      reader->SetFileName(volumeFilename.c_str());

      vtkSmartPointer<vtkSLCReader> reader2 =
        vtkSmartPointer<vtkSLCReader>::New();
      reader2->SetFileName(contourFilename.c_str());

      // 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());

      // Make sure we have only tetrahedra.
      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,  0.0);
      opacityTransferFunction->AddPoint(120.0, 0.2);
      opacityTransferFunction->AddPoint(255.0, 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 that renders the volume data.
      vtkSmartPointer<vtkHAVSVolumeMapper> volumeMapper =
        vtkSmartPointer<vtkHAVSVolumeMapper>::New();
      volumeMapper->SetInputConnection(trifilter->GetOutputPort());
      volumeMapper->SetLevelOfDetail(false);
      volumeMapper->SetGPUDataStructures(false);
      volumeMapper->SetKBufferSizeTo2();

      // The volume holds the mapper and the property and can be used to
      // position/orient the volume.
      vtkSmartPointer<vtkVolume> volume =
        vtkSmartPointer<vtkVolume>::New();
      volume->SetMapper(volumeMapper);
      volume->SetProperty(volumeProperty);

      // 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);

      // First test if mapper is supported
      renWin->SetSize(300, 300);
      renWin->Render();

      int supported = volumeMapper->SupportedByHardware(ren1);

      vtkSmartPointer<vtkTextActor> textActor =
        vtkSmartPointer<vtkTextActor>::New();
      textActor->SetInput("Required Extensions\nNot Supported");
      textActor->SetDisplayPosition( 150, 150 );
      textActor->GetTextProperty()->SetJustificationToCentered();
      textActor->GetTextProperty()->SetFontSize(30);

      if(!supported)
      {
        ren1->AddViewProp(textActor);
      }
      else
      {
        ren1->AddViewProp(actor);
        ren1->AddViewProp(volume);
      }

      ren1->ResetCamera();
      ren1->GetActiveCamera()->Azimuth(20.0);
      ren1->GetActiveCamera()->Elevation(10.0);
      ren1->GetActiveCamera()->Zoom(1.5);

      // Test default settings
      renWin->Render();

      // Test kbuffer size 6
      volumeMapper->SetKBufferSizeTo6();
      renWin->Render();

      // Test GPU Data structures
      volumeMapper->SetGPUDataStructures(true);
      renWin->Render();

      // Test Field Level of Detail
      volumeMapper->SetLevelOfDetail(true);
      volumeMapper->SetLevelOfDetailMethodField();
      renWin->Render();

      // Test Area Level of Detail
      volumeMapper->SetLevelOfDetailMethodArea();
      renWin->Render();

      // Return to default KBuffer size and Level of Detail
      volumeMapper->SetLevelOfDetail(false);
      volumeMapper->SetKBufferSizeTo2();
      renWin->Render();

      iren->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(HAVSVolumeMapper)

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

    add_executable(HAVSVolumeMapper MACOSX_BUNDLE HAVSVolumeMapper.cxx)

    target_link_libraries(HAVSVolumeMapper ${VTK_LIBRARIES})

### Download and Build HAVSVolumeMapper

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

    cd HAVSVolumeMapper/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:

    ./HAVSVolumeMapper

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.