[JAVA3D] Grouping problem ( non-affine transform )

[Morten Gustavsen]

Hi all, I want to group objects in such a way that when I pick the parent of the group, all children follows with it. But when I pick a child, the child should move freely and independent of the parent. The scenegraph is rearranged when objects are picked interactively by the user (all objects are live in the scene). I use the the "moveTo(BranchGroup bg)" method to create this structure of the scenegraph.                                   Locale                                     |                                 BGRoot                                     |                                 TGParent                              /           |                     BGchild1    BGChild2                            |              |                     TGChild1    TGChild2   When I move my TGParent all children follows with it, and if the TGParent is not rotated everything works just the way I want. The problem arises when I rotate the TGParent. When I then try to move one of its children, they move in the opposite way of what it should. To solve this problem I have tried to subtract the virtual world coordinates of the TGChild from the virtual world coordinates of the TGParent.  ( childTransform3d.sub(parentTransform3d)) ). When I then try to pick and move one of the child objects, I am not able to set the transform of the child-object. I get the error-message: javax.media.j3d.BadTransformException: TransformGroup: non-affine transform Could someone please help me if they have any thoughts about the problem -Morten Gustavsen