Maybe this is problem solved a long ago. I’ve searched but gotten no satisifying results. My question is as simple as below:
How to get the 3D coordinates when I click on the stage (View3D)?
I’ve found there are project/unproject functions decleared in View3D/Camera3D, however I don’t quite understand these two functions,e.g. when i click on the stage I get 2D coordinates while the function unproject receives 3 coordinates. What’s the third parameter? May I just pass it 0?

Thanks a lot!