we used WPF library come from http://3dtools.codeplex.com, we used TrackballDecorator and ScreenSpaceLines3D to display 3d lines and 3d axis.
the ScreenSpaceLines3D provide rotation and zoom functions. we want added a HitTest method for 3d lines. we can highlight the line when mouse move on it.
we plan to get current position in 3d, but the position always returns is wrong when we rotate the viewer or we changed Positon and LookDirection of the camera.