Convert X,Y (Window) to X,Y,Z World Coordinates (OpenGL)

How do i convert a windows coordinates (X,Y) to OpenGL coordinates (X,Y,Z)? I have heard about gluUnProject(…) but i’am not using C and i don’t know how to get this function (file) for Delphi!

The Opengl - Delphi site:
has a delphi source / tutorial called >>Aiming - function ‘glReadPixels’<<
I have used this to transfer the object coordinates to a statusbar, when the mouse is over an object.

Håber det hjælper dig