Chanllage about advanced mouse picking

[allked]

Recently, i am creating some visualization about buildings, i made a hole building in 3dsmax, it has four floors,but my problem is how to use mouse to pick different floors with only 1 3ds mesh loaded, i thought to create 4 invisible box ,not actual mesh,just use the code to determine which floor is.and simply,is this a collision problem between 3dline and a 3d box?
but how to do in Irrlicht,any detial? thanks

[JP]

create your 3D line, you might find some methods in CollisionSceneManager useful for that, and then get each box and in turn use its method to see if the line intersects with that box.