Intersection math question (HUD related)

[cascade]

Hi, I'm having trouble with a hopefully simple math problem:

What I want to do:

Given a plane defined by a quadrilateral (not necessarily rectangular) and an intersection point lying in this plane.


What is the question:

How do I compute the (normalized) position of the intersection point relative to the plane ?


I think the special case of a rectangular quadrilateral is rather simple but I hope that someone might know how to solve it for the general case.

The idea behind this is to get normalized intersection positions on quads used for the HUD. So for an intersection point in the virtual world I get a callback telling me that this event occurred at (.07,.85) on quad(radar).

Thanks,
Ca$