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# OrientedArrow

VTKEx/Java/GeometricObjects/OrientedArrow

### Description

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.

Other languages

See (Cxx), (Python), (CSharp)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### 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);
            }
          });
      }
    }