I realise this has been covered before, but having read all the relevant threads I've not found a solution.

What I'd like to do is know whether a 3d object in 3d space is under the cursor or not.

The sensible way to do this seems to me to take the x/y screen position of the cursor, give it a z position (all my objects are at the same depth, handily, so this is known and constant) and 'ask' processing where it is.

I've come across modelX/Y/Z and screenX/Y/Z, it seemed that feeding the values described above into modelX/Y was what I was after, but doing that and creating a box at the returned vales, well, the box doesn't follow the cursor. It seems to do something similar to creating a box at mouseX, mouseY and a known Z.

What I would like to know is whether there is an inbuilt way of doing this. Am I just using modelX etc wrong?

I realise I could do this mathematically but that seems to me to negate the point of using a 3d engine.

Would appreciate any help/pointers.

I'll rephrase because I'm not the best at explaining:

I'd like an object to follow the mouse pointer exactly, yet exist in 3d space at a known Z position.

I'd wondered about that but was trying to avoid it because of the number of objects on screen (bout 5000, although they're all just boxes, mostly of the same dimensions).

I'd wanted to avoid extra loops, but you've made me realise I don't need one, I can do it when it loops through to draw them.

Thank you.