# NegativeIndices

VTKExamples/Cxx/Images/NegativeIndices

### Code

NegativeIndices.cxx

    #include <vtkVersion.h>
    #include <vtkSmartPointer.h>
    #include <vtkImageData.h>

    int main(int, char *[])
    {
      // Create an image data
      vtkSmartPointer<vtkImageData> imageData =
        vtkSmartPointer<vtkImageData>::New();

      // Specify the size of the image data
      imageData->SetExtent(-5, 5, -5, 5, -5, 5);

      // Fill every entry of the image data with "2.0"
      int* extent = imageData->GetExtent();

    #if VTK_MAJOR_VERSION <= 5
      imageData->SetNumberOfScalarComponents(1);
    #else
      imageData->AllocateScalars(VTK_UNSIGNED_CHAR,1);
    #endif

      std::cout << "Extent: " << " xmin: " << extent[0] << " xmax: " << extent[1]
                << " ymin: " << extent[2] << " ymax: " << extent[3]
                << " zmin: " << extent[4] << " zmax: " << extent[5] << std::endl;

      for (int z = extent[4]; z < extent[5]; z++)
      {
        for (int y = extent[2]; y < extent[3]; y++)
        {
          for (int x = extent[0]; x < extent[1]; x++)
          {
            imageData->SetScalarComponentFromDouble(x,y,z,0,2.0);
          }
        }
      }

      // Retrieve the entries from the image data and print them to the screen
      for (int z = extent[4]; z < extent[5]; z++)
      {
        for (int y = extent[2]; y < extent[3]; y++)
        {
          for (int x = extent[0]; x < extent[1]; x++)
          {
            // Zero is the component, add another loop if you have more
            // than one component
            double v = imageData->GetScalarComponentAsDouble(x,y,z,0);
            // Eo something with v
            std::cout << v << " ";
          }
          std::cout << std::endl;
        }
        std::cout << std::endl;
      }
      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(NegativeIndices)

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

    add_executable(NegativeIndices MACOSX_BUNDLE NegativeIndices.cxx)

    target_link_libraries(NegativeIndices ${VTK_LIBRARIES})

### Download and Build NegativeIndices

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

    cd NegativeIndices/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:

    ./NegativeIndices

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.