Adding a branchgroup to a live scene with swing buttons

Question

Hi, please have a look on the following code.
I want to add "objects" in a live scene.
I've planned to do this by attaching a new branchgroup
to an existing alive structure.
The code of the new branchgroup is in the action of a swing button.
// method "addObject" called by the button
private class addObject extends BranchGroup implements ActionListener {
public void actionPerformed(ActionEvent event){
BranchGroup obj = new BranchGroup ();
// Creation of a sphere
Sphere sphere = new Sphere (0.3f);
System.out.println(sphere);
obj.addChild (sphere);
obj.addChild (this);
System.out.println("add action");
System.out.println(obj);
// definition of the button
     private JButton ajout = new JButton("Ajout");
     JPanel p2 = new JPanel();
ajout.addActionListener(new addObject());
p2.add(ajout);
// code to attach the branchgroup
     BranchGroup b2 = new addObject();
System.out.println("br "+b2);
objRoot.addChild(b2);
objRoot.compile();
return objRoot;
But, the Sphere is not seen on the scene
even if the action on the button seems to work.
And if i do twice, i get this error :
Exception occurred during event dispatching:
javax.media.j3d.MultipleParentException: Group.addChild: child already has a parent
     at javax.media.j3d.GroupRetained.checkValidChild(GroupRetained.java:442)
     at javax.media.j3d.GroupRetained.addChild(GroupRetained.java:451)
     at javax.media.j3d.Group.addChild(Group.java:266)
     at applet3d.Scene3D$addObject.actionPerformed(Scene3D.java:588)
     at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1450)
     at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1504)
     at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:378)
     at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250)
     at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:216)
     at java.awt.Component.processMouseEvent(Component.java:3715)
     at java.awt.Component.processEvent(Component.java:3544)
     at java.awt.Container.processEvent(Container.java:1164)
     at java.awt.Component.dispatchEventImpl(Component.java:2593)
     at java.awt.Container.dispatchEventImpl(Container.java:1213)
     at java.awt.Component.dispatchEvent(Component.java:2497)
     at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:2451)
     at java.awt.LightweightDispatcher.processMouseEvent(Container.java:2216)
     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2125)
     at java.awt.Container.dispatchEventImpl(Container.java:1200)
     at java.awt.Window.dispatchEventImpl(Window.java:914)
     at java.awt.Component.dispatchEvent(Component.java:2497)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:339)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:131)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:98)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:85)
Anyone can help ?
Thanks

Answer 1

I've changed the code a bit.
I don't have the exception anymore, and when i press the button, i really create instances of sphres, but they are not seen in the Scene.
Any idea someone ?
package applet3d;
import java.awt.*;
import java.awt.GraphicsConfiguration;
import java.awt.event.*;
import com.sun.j3d.utils.geometry.*;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.behaviors.mouse.*;
import com.sun.j3d.utils.behaviors.keyboard.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import javax.swing.*;
public class Scene3Db extends JFrame implements ActionListener, MouseListener {
     private static final long serialVersionUID = 1L;
     private SimpleUniverse su;
private BranchGroup sceneBG, mainBG, shapeBG, objRoot;
private TransformGroup mainTG, shapeTG, cameraTG;
private BoundingSphere bounds;
private Material material2;
private static int mycount = 1;
//declaration des elements du gui
private JLabel etiq1;
private JCheckBox couleur;
//constructeur
public Scene3Db() {
Container contentPane = getContentPane();
//BorderLayout bl = new BorderLayout();
//setLayout(bl);
GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();
Canvas3D c = new Canvas3D(config);
contentPane.add("Center", c);
JPanel p1 = new JPanel();
p1.add(presentationPanel());
contentPane.add("North", p1);
JPanel p2 = new JPanel();
JButton ajout = new JButton("Ajout");
addObject addObjBG = new addObject();
ajout.addActionListener(addObjBG);
//objRoot.addChild(addObjBG); //pb !
p2.add(ajout);
contentPane.add("South", p2);
SimpleUniverse su = new SimpleUniverse(c);
BranchGroup scene = createSceneGraph(su);
//scene.setCapability( BranchGroup.ALLOW_BOUNDS_READ );
su.getViewingPlatform().setNominalViewingTransform();
su.addBranchGraph(scene);
addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}});
setSize(800,600); //Taille Fenetre
show();
repaint();
//cr�ation du graphe de sc�ne
public BranchGroup createSceneGraph(SimpleUniverse su) {
//cr�ation d'un BG racine de l'arbre 3D
//BranchGroup objRoot = new BranchGroup();
objRoot = new BranchGroup();
objRoot.setCapability( BranchGroup.ALLOW_PICKABLE_READ );
objRoot.setCapability( BranchGroup.ALLOW_PICKABLE_WRITE );
objRoot.setCapability(BranchGroup.ALLOW_CHILDREN_EXTEND);
objRoot.setCapability(BranchGroup.ALLOW_DETACH);
objRoot.setCapability(Group.ALLOW_CHILDREN_READ);
objRoot.setCapability(Group.ALLOW_CHILDREN_WRITE);
objRoot.setCapability(Group.ALLOW_CHILDREN_EXTEND);
//cr�ation d'un bounds pour le fond et la lumi�re
BoundingSphere bounds =
new BoundingSphere(new Point3d(0.0,0.0,0.0), 100.0);
Color3f bgColor = new Color3f(0.05f, 0.05f, 0.2f);
Background bg = new Background(bgColor);
bg.setApplicationBounds(bounds);
objRoot.addChild(bg);
Color3f light1Color = new Color3f(1.0f, 1.0f, 0.9f);
Vector3f light1Direction = new Vector3f(4.0f, -7.0f, -12.0f);
DirectionalLight light1
= new DirectionalLight(light1Color, light1Direction);
light1.setInfluencingBounds(bounds);
objRoot.addChild(light1);
BranchGroup sceneObj = new BranchGroup();
//cr�ation d'un TG pour la gestion d'�chelle
TransformGroup objScale = new TransformGroup();
Transform3D t3d = new Transform3D();
t3d.setScale(0.4);
objScale.setTransform(t3d);
sceneObj.addChild(objScale);
//cr�ation d'un TG pour permettre la modification des objets visuels
TransformGroup objTrans = new TransformGroup();
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
objTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
objScale.addChild(objTrans);
MouseRotate myMouseRotate = new MouseRotate();
myMouseRotate.setTransformGroup(objTrans);
myMouseRotate.setSchedulingBounds(new BoundingSphere());
sceneObj.addChild(myMouseRotate);
MouseTranslate myMouseTranslate = new MouseTranslate();
myMouseTranslate.setTransformGroup(objTrans);
myMouseTranslate.setSchedulingBounds(new BoundingSphere());
sceneObj.addChild(myMouseTranslate);
MouseZoom myMouseZoom = new MouseZoom();
myMouseZoom.setTransformGroup(objTrans);
myMouseZoom.setSchedulingBounds(new BoundingSphere());
sceneObj.addChild(myMouseZoom);
//Canvas3D c = new Canvas3D(null);
//PickHighlightBehavior pickBeh = new
//PickHighlightBehavior(c, objRoot, bounds);
BranchGroup b2 = new addObject();
objRoot.addChild(b2);
//System.out.println("br "+b2);
objRoot.addChild(sceneObj);
//objRoot.addChild(b2);
objRoot.compile();
return objRoot;
public JPanel presentationPanel() {
     JPanel panel1 = new JPanel();
etiq1 = new JLabel
("Modelisation d'un environnement naturel en 3D / � 2005 cnam ubo");
panel1.add(etiq1);
return panel1;
//fonction ajout d'objet
private class addObject extends BranchGroup implements ActionListener {
private addObject () {
this.setCapability(BranchGroup.ALLOW_CHILDREN_EXTEND);
public void actionPerformed(ActionEvent event){
BranchGroup obj = new BranchGroup ();
// Cr�ation d'une sph�re
Sphere sphere = new Sphere (0.3f, Sphere.GENERATE_NORMALS, 20);
System.out.println(sphere);
Transform3D sphereRandromTransform = new Transform3D ();
sphereRandromTransform.setTranslation(new Vector3d(randomCoord(),randomCoord(),randomCoord()));
TransformGroup sphereTG = new TransformGroup (sphereRandromTransform);
sphereTG.addChild(sphere);
obj.addChild(sphereTG);
this.addChild(obj);
System.out.println("action ajout");
System.out.println(obj);
private double randomCoord () {
double coord = Math.random();
return coord>=0.5?-coord*5:coord*5;
public void mouseClicked( MouseEvent e ) {
public void mouseEntered( MouseEvent e ) {
public void mouseExited( MouseEvent e ) {
public void mousePressed( MouseEvent e ) {
// if (e.getSource()==reset) {
//setNominalPositionAndOrientation();
public void mouseReleased( MouseEvent e ) {
//mode = STILL;
public void actionPerformed(ActionEvent e) {
Object target = e.getSource();
if (target == couleur) {
if (couleur.isSelected()){
//scene.pickBeh;
public static void main(String[] args) {
     try {
//D�finition du type d'affichage boite de dialogue
//UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
          } catch (Exception exc) {
System.err.println("Erreur de chargement L&F: " + exc);
new Scene3Db();
}