# OrientedArrow

VTKExamples/Java/GeometricObjects/OrientedArrow

This example illustrates how to create and display an arrow that passes through two points.

It demonstrates two different ways to apply the transform: 1. Use vtkTransformPolyDataFilter to create a new transformed polydata. This method is useful if the transformed polydata is needed later in the pipeline, e.g. vtkGlyph3DFilter. 2. Apply the transform directly to the actor using vtkProp3D's SetUserMatrix. No new data is produced.

Author: Bharatesh Chakravarthi Affiliation: VE Lab, Chung Ang University, Seoul, South Korea.

### Code

OrientedArrow.java

    import java.awt.BorderLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;

    import javax.swing.JButton;
    import javax.swing.JFrame;
    import javax.swing.JPanel;
    import javax.swing.SwingUtilities;

    import vtk.vtkActor;
    import vtk.vtkArrowSource;
    import vtk.vtkNativeLibrary;
    import vtk.vtkPanel;
    import vtk.vtkPolyDataMapper;
    import vtk.vtkMinimalStandardRandomSequence;
    import vtk.vtkNamedColors;
    import vtk.vtkMath;
    import vtk.vtkMatrix4x4;
    import vtk.vtkTransform;
    import vtk.vtkTransformPolyDataFilter;
    import vtk.vtkSphereSource;

    //Author: Bharatesh Chakravarthi
    //Affiliation: VE Lab, Chung Ang University, Seoul, South Korea.

    public class OrientedArrow extends JPanel implements ActionListener {
          private static final long serialVersionUID = 1L;
          private vtkPanel renWin;
          private JButton exitButton;

          // -----------------------------------------------------------------
          // Load VTK library and print which library was not properly loaded
          static {
            if (!vtkNativeLibrary.LoadAllNativeLibraries()) {
              for (vtkNativeLibrary lib : vtkNativeLibrary.values()) {
                if (!lib.IsLoaded()) {
                  System.out.println(lib.GetLibraryName() + " not loaded");
                }
              }
            }
            vtkNativeLibrary.DisableOutputWindow(null);
          }
          // -----------------------------------------------------------------

          public OrientedArrow() {
            super(new BorderLayout());

            vtkNamedColors Color = new vtkNamedColors();

            //For Actor Color
            double StartActorColor[] = new double[4];
            double ArrowActorColor[] = new double[4];
            double EndActorColor[] = new double[4];
            //Renderer Background Color
            double BgColor[] = new double[4];

            //Change Color Name to Use your own Color for Change StartActor Color
            Color.GetColor("GreenYellow",StartActorColor);
            //Change Color Name to Use your own Color for Change StartActor Color
            Color.GetColor("Tomato",ArrowActorColor);
            //Change Color Name to Use your own Color for Change StartActor Color
            Color.GetColor("Yellow",EndActorColor);
            //Change Color Name to Use your own Color for Renderer Background
            Color.GetColor("SlateGray",BgColor);

          //Create a Arrow
          vtkArrowSource ArrowSource = new vtkArrowSource();

          double sp[] = new double[3];
          double ep[] = new double[3];

          // Generate a random start and end point
          vtkMinimalStandardRandomSequence RandomNumbers = new vtkMinimalStandardRandomSequence();
          RandomNumbers.SetSeed(8775070);
          for(int i=0;i<3;++i) {
              RandomNumbers.Next();
              sp[i]=RandomNumbers.GetRangeValue(-10, 10);
              RandomNumbers.Next();
              ep[i]=RandomNumbers.GetRangeValue(-10, 10);
          }

          // Compute a basis
          double normalizedX[] = new double[3];
          double normalizedY[] = new double[3];
          double normalizedZ[] = new double[3];

          // The X axis is a vector from start to end
          vtkMath ss = new vtkMath();
          ss.Subtract(ep, sp, normalizedX);
          double length;
          length=ss.Norm(normalizedX);
          ss.Normalize(normalizedX);

          // The Z axis is an arbitrary vector cross X
          double arbitary[] = new double[3];
          for(int i=0;i<3;++i) {
              RandomNumbers.Next();
              arbitary[i]=RandomNumbers.GetRangeValue(-10, 10);
          }
          ss.Cross(normalizedX, arbitary, normalizedZ);
          ss.Normalize(normalizedZ);
          // The Y axis is Z cross X
          ss.Cross(normalizedZ, normalizedX, normalizedY);
          vtkMatrix4x4 Matrix = new vtkMatrix4x4();

          // Create the direction cosine matrix
          Matrix.Identity();
          for(int i=0;i<3;i++) {
              Matrix.SetElement(i, 0, normalizedX[i]);
              Matrix.SetElement(i, 1, normalizedY[i]);
              Matrix.SetElement(i, 2, normalizedZ[i]);
          }

          //Apply the transforms
          vtkTransform Transform = new vtkTransform();
          Transform.Translate(sp);
          Transform.Concatenate(Matrix);
          Transform.Scale(length, length, length);

          // Transform the polydata
          vtkTransformPolyDataFilter TransformPD = new vtkTransformPolyDataFilter();
          TransformPD.SetTransform(Transform);
          TransformPD.SetInputConnection(ArrowSource.GetOutputPort());

          vtkPolyDataMapper Mapper = new vtkPolyDataMapper();
          vtkActor Actor = new vtkActor();
          Mapper.SetInputConnection(ArrowSource.GetOutputPort());

          Actor.SetMapper(Mapper);
          Actor.SetUserMatrix(Transform.GetMatrix());
          Actor.GetProperty().SetColor(ArrowActorColor);

          //Create spheres for start and end point
          vtkSphereSource SphereStartSource = new vtkSphereSource();
          SphereStartSource.SetCenter(sp);
          SphereStartSource.SetRadius(0.8);

          vtkPolyDataMapper SphereStartMapper = new vtkPolyDataMapper();
          SphereStartMapper.SetInputConnection(SphereStartSource.GetOutputPort());

          vtkActor SphereStartActor = new vtkActor();
          SphereStartActor.SetMapper(SphereStartMapper);
          SphereStartActor.GetProperty().SetColor(StartActorColor);

          vtkSphereSource SphereEndSource = new vtkSphereSource();
          SphereEndSource.SetCenter(ep);
          SphereEndSource.SetRadius(0.8);

          vtkPolyDataMapper SphereEndMapper = new vtkPolyDataMapper();
          SphereEndMapper.SetInputConnection(SphereEndSource.GetOutputPort());

          vtkActor SphereEndActor = new vtkActor();
          SphereEndActor.SetMapper(SphereEndMapper);
          SphereEndActor.GetProperty().SetColor(EndActorColor);

          renWin = new vtkPanel();
          renWin.GetRenderer().AddActor(Actor);
          renWin.GetRenderer().AddActor(SphereStartActor);
          renWin.GetRenderer().AddActor(SphereEndActor);
          renWin.GetRenderer().SetBackground(BgColor);;
          renWin.resetCamera();

          // Add Java UI components
          exitButton = new JButton("Exit");
          exitButton.addActionListener(this);

          add(renWin, BorderLayout.CENTER);
          add(exitButton, BorderLayout.SOUTH);
          }

          /** An ActionListener that listens to the button. */
          public void actionPerformed(ActionEvent e) {
            if (e.getSource().equals(exitButton)) {
              System.exit(0);
            }
          }

          public static void main(String s[]) {
            SwingUtilities.invokeLater(new Runnable() {
              public void run() {
                JFrame frame = new JFrame("Oriented Arrow");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.getContentPane().setLayout(new BorderLayout());
                frame.getContentPane().add(new OrientedArrow(), BorderLayout.CENTER);
                frame.setSize(400, 400);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
              }
            });
          }
        }