Screen space to world space?

Hey everyone,
quick simple question: I have an object (red cross on screenshots below) moving in screen space e.g. from -1 to 1, how can I map this coordinates to “corresponding” point in world space, e.g. coordinates of green square?


Okay, for some reason screenshots didn’t attached. So, here they are:

have a look at the intersect nodes and their help patches (press F1 on selected node).

i think they are doing exactly what you are looking for…