# ZBuffer

VTKExamples/Cxx/Utilities/ZBuffer

### Code

ZBuffer.cxx

    // This demo creates depth map for a polydata instance by extracting
    // exact ZBuffer values.
    #include <vtkSmartPointer.h>

    #include <vtkPolyDataMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkXMLPolyDataReader.h>
    #include <vtkBMPWriter.h>
    #include <vtkWindowToImageFilter.h>
    #include <vtkImageShiftScale.h>

    int main(int argc, char *argv[])
    {
      if (argc < 3)
      {
          std::cout << "Usage: " << argv[0]
                    << " input(.vtp) output(.bmp)"
                    << std::endl;
          return EXIT_FAILURE;
      }

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      vtkSmartPointer<vtkRenderWindowInteractor> interactor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      vtkSmartPointer<vtkXMLPolyDataReader> fileReader =
        vtkSmartPointer<vtkXMLPolyDataReader>::New();
      vtkSmartPointer<vtkWindowToImageFilter> filter =
        vtkSmartPointer<vtkWindowToImageFilter>::New();
      vtkSmartPointer<vtkBMPWriter> imageWriter =
        vtkSmartPointer<vtkBMPWriter>::New();
      vtkSmartPointer<vtkImageShiftScale> scale =
        vtkSmartPointer<vtkImageShiftScale>::New();

      // Read .vtp file
      fileReader->SetFileName(argv[1]);

      //Build visualization enviroment
      mapper->SetInputConnection(fileReader->GetOutputPort());
      actor->SetMapper(mapper);
      renderer->AddActor(actor);
      renWin->AddRenderer(renderer);
      interactor->SetRenderWindow(renWin);
      renWin->Render();

      // Create Depth Map
      filter->SetInput(renWin);
    #if VTK_MAJOR_VERSION > 8 || VTK_MAJOR_VERSION == 8 && VTK_MINOR_VERSION >= 1
      filter->SetScale(1);
    #else
      filter->SetMagnification(1);
    #endif
      filter->SetInputBufferTypeToZBuffer();        //Extract z buffer value

      scale->SetOutputScalarTypeToUnsignedChar();
      scale->SetInputConnection(filter->GetOutputPort());
      scale->SetShift(0);
      scale->SetScale(-255);

      // Write depth map as a .bmp image
      imageWriter->SetFileName(argv[2]);
      imageWriter->SetInputConnection(scale->GetOutputPort());
      imageWriter->Write();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ZBuffer)

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

    add_executable(ZBuffer MACOSX_BUNDLE ZBuffer.cxx )

    target_link_libraries(ZBuffer ${VTK_LIBRARIES})

### Download and Build ZBuffer

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

    cd ZBuffer/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:

    ./ZBuffer

WINDOWS USERS

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