I've maybe explained it a bit badly - I was thinking "like the soil triangle", but for sexuality. So you'd have the "100% gay corner" rather than "100% sandy".

edit: oh, yeah. A "straight line" between 100% straight and 100% gay would be too simple, in that there should be more options. Should have used a different term, but what I mean is that you can't just assign people a single number here, people are more complex than that.