glRotate and getting new vertices

Hello there,
I am doing an application for my project at university and didn’t know if there was a way to get new vertices just X and Y after a shape has been rotated via glRotatef().
My application is basically a crane which can pick up a box then move it around the crane’s position and place it back down. This shall then need to mark the location of the box and allow it to be left behind.

I have been trying for hours to achieve this, and if I can’t get this bit done, my application is basically useless.

Thanks Steve

Try looking at this example