UPDATE: draws the curvature of 1st side PREVIOUS: you can drag the lines and dots. ABOUT LONG-TERM GOAL: eventually I want to have it draw the lens (with 0 meaning infinite and the radii values defining the curvatures), have a system for finding the direction of the normal for any point on the edge, use laws of refraction to bend any light ray inwards, and then outwards, and project it inwards to demonstrate the way that a lens works and how it curves light. maybe eventually be able to mathematically define the focal point, the kind of lens, have input protection, and other things. please see http://en.wikipedia.org/wiki/Lens_%28optics%29
