I am interested in solving the null geodesic between two points in the presence of a gravitational mass, assuming that everything takes place in 2 dimensions (i.e., no Z coordinate). The following is known: -x and y coordinates of first point -x and y coordinates of second point -x and y coordinates of gravitational mass -mass of gravitational body I need an equation describing the curve of the null geodesic. The purpose of this is for use in a basic computer simulation I'm toying around with, so a basic function with the above variables for input would be very helpful - integrals and derivatives, not so much. So I am hoping for a solution relating x and y in a 2D flat plane (since that's easiest to represent on a computer screen) Is there a simple solution that can work in the general case, given the above inputs (or at least an approximation, up to only a few orders in x or y)? If the solution is not so simple (i.e., integrals and derivatives), is there at least just one solution that I could solve with not too much effort? I hope I've provided enough to describe my problem - feel free to ask more if I haven't.