Adding Two Spheres to Same Transform Group

Question

Should be a simple question. How do I add two spheres to the same TransformGroup?
With this code, only one sphere is displayed:
TransformGroup tg = new TransformGroup();
Sphere sphere001 = new Sphere(0.1f);
Vector3f vector = new Vector3f(0.0f, 0.0f, 0.0f);
Transform3D transform = new Transform3D();
transform.setTranslation(vector);
tg.setTransform(transform);
tg.addChild(sphere001);
Sphere sphere002 = new Sphere(0.1f);
Vector3f vector002 = new Vector3f(0.0f, 0.5f, 0.0f);
Transform3D transform2 = new Transform3D();
transform2.setTranslation(vector002);
tg.setTransform(transform2);
tg.addChild(sphere002);

Answer 1

Not totally sure but i think the second tg.setTransform() overwrites the previous transform thus both spheres are transformed to the same insertion point, so the 2nd sphere is "covering" the 1st? Maybe each transform group can only apply 1 common set of transform on all child objects.
I had a similar problem and the following works for me:
Try putting the 2 spheres in seperate BranchGroups, this ensures that there are 2 independent transforms. You can then add the 2 BranchGroups to either your SimpleUniverse to be displayed (i'm guessing thats your objective) or even to another common TransformGroup (say you want the 2 spheres to be inserted at 2 differnt points but then moved together to another location)
//1st BranchGroup contains some Transform Group
BranchGroup bg1 = new BranchGroup();
TransformGroup tg1 = new TransformGroup();
Sphere sphere001 = new Sphere(0.1f);
Vector3f vector = new Vector3f(0.0f, 0.0f, 0.0f);
Transform3D transform = new Transform3D();
transform.setTranslation(vector);
tg1.setTransform(transform);
tg1.addChild(sphere001);
bg1.addChild(tg1);
//2nd BranchGroup constains another Transform Group
BranchGroup bg2 = new BranchGroup();
TransformGroup tg2 = new TransformGroup();
Sphere sphere002 = new Sphere(0.1f);
Vector3f vector002 = new Vector3f(0.0f, 0.5f, 0.0f);
Transform3D transform2 = new Transform3D();
transform2.setTranslation(vector002);
tg2.setTransform(transform2);
tg2.addChild(sphere002);
bg2.addChild(tg2);
//eg, moving the 2 spheres together after they are inserted in different places
TransformGroup moveTogether = new TransformGroup();
Vector3f vector003 = new Vector3f(0.2f, 0.2f, 0.2f);
Transform3D transform3 = new Transform3D();
transform3.setTranslation(vector003 );
moveTogether.addChild(bg1);
moveTogether.addChild(bg2);