How to select a Geometry in 3D graph

I drawed some lines in the 3D graph, I want to pick up a trigger when I click over the line.
Problem is : the line is in 3D, I can only get the 2D position of cursor by inputManager.getCursorPosition();
Is there any good way to get the result about which line is being choosed?

New to JME :grin:

Seriously, do the tutorials. What you want is picking.

understand, thanks…