I'm doing some 3d plotter with OpenTK and I need the user to be able to select each individual plotted point and know the coordinates of it. Obviously I know the 3Dcoordinates of all points because that's how i plot them. What I'm not sure how to do is to get the coordinates FROM the glControl with is what the user interacts with. It would be nice if the user could click some point in the glcontrol and know its coordinates. Any ideas/examples of how to do that?