An additional question...
I'm trying to obtain positions of multiple picked points. In fact, I am able to realize this already.
My question is how to display all of those picked points? Whenever I picked a second point (or the third, fourth...etc), the first point (first n-1 points) will be removed from the screen. I just want to realize something like : whenever I picked one additional point, the former picked points won't be removed at all.
Use a WakeupOnAWTEvent to get notified when user clicks. Use the click position to pick using pickCanvas. Read the intersections back. If you need the intersection in world space you have to transform the intersection with the intersected nodes localtoVWorld transform.