Adding a goemetry object in an already started applet, behvior ?

Question

Hello there,
I would like to add a geometric form (cube, box, cone etc..) in an already
started applet. I think creating a specific behavior would be the most
appropriate.
Has anybody done this kind of thing before ?
Many thanks.
Gwena�l

Answer 1

Great thread! I am having difficulty with removing objects from a scene graph. See source code below:
addTarget creates a grpahicsObject (class consisting of some data, mainly a 3d object which is attached to a transformGroup).
//function to add an aircrafat to display
     //attemps to create the aircraft in the specified location
     //returns false if the spot is not null
     public boolean addTarget(int location, float x, float y, float z)
          if(targets[location]!=null)
               return false;
          //create transform vector
          Vector3f targetTransform = new Vector3f(x,y,z);
          //create the object
          targets[location]= new GraphicsObject(targetTransform, TARGET_COLOR);
          //add it to the scene graph
          sadist.addObject(targets[location].getTransformGroup());
          return true;
//sadist is an object that contains my universe and pretty much controls my display
//the add object code adds the created to the scene graph by adding the transform group to a newly created branchgroup and than adding that to the mother branchgroup. The mother branchgroup was attached to the simple universe object (see code snipit)
private Applet CreateWorld()
          setLayout(new BorderLayout());
     //create a new canvas
     Canvas3D canvas3D = new Canvas3D(null); // NEED TO PASS IN SOMETHING
     //add canvas to applet
     add("Center", canvas3D);
     BranchGroup scene = createSceneGraph();
     mother = new BranchGroup();
          mother.setCapability(BranchGroup.ALLOW_DETACH);
          mother.setCapability(Group.ALLOW_CHILDREN_READ);
     mother.setCapability(Group.ALLOW_CHILDREN_WRITE);
     mother.setCapability(Group.ALLOW_CHILDREN_EXTEND);
     mother.addChild(scene);
     // SimpleUniverse is a Convenience Utility class
     // code reuse saves time
     simpleU = new SimpleUniverse(canvas3D);
          ViewingPlatform vp = simpleU.getViewingPlatform();
          TransformGroup steerTG = vp.getViewPlatformTransform();
          //create my transform
          Transform3D t3d = new Transform3D();
          steerTG.getTransform(t3d);
          //lookAt( from here, look here, vector up)
          t3d.lookAt( new Point3d (2,2,2),
                         new Point3d (0,0,0),
                         new Vector3d(0,1,0) );
          t3d.invert(); //inverted since the position is relative to the viewer
          //set the transform for the transform group
          steerTG.setTransform(t3d);
          simpleU.addBranchGraph(mother);
     return(this);
     //function to add transofrm group to scene graph
     public void addObject(TransformGroup object)
          //should I create a new branch graph, add the transform group, and then
          //add that to the simple u
          //I don't think this is right as I have no real way of identifying this
          //I need to look into a removeChild or something
          //could result in 1000's of null nodes on scene graph
          //yuck...
          System.out.println("going to add the transformg group to the branchgroup");
          BranchGroup t = new BranchGroup();
          t.setCapability(BranchGroup.ALLOW_DETACH);
          t.setCapability(Group.ALLOW_CHILDREN_READ);
          t.setCapability(Group.ALLOW_CHILDREN_WRITE);
     t.setCapability(Group.ALLOW_CHILDREN_EXTEND);
          t.addChild(object);
          t.compile();
          //simpleU.addBranchGraph(t);
          mother.addChild(t);
When I run the code with a tester function I can add the objects just fine but when I try to remove them (see code below) it doesn�t work.
//removal of targets will take place
     public void removeObject(int location) throws CapabilityNotSetException
          try
               //I tried detaching the branchgroup via the detach() function
               //howeve that wasn't successful either.
               mother.removeChild(location);
          catch(CapabilityNotSetException e)
               throw e;
Any advice you could give would be great.
Thanks,
Mike