Scinawa / spiral

I was at EndSummerCamp and i was around 20 when i wrote this. A guy I have never met before (i rememeber he was coding for openstreetmaps) asked me the algoritm to draw a spiral: their problem was that their maps was slow to load complitely on screen, and since they started to load the page from the top left, they had to change strategy. and they needed an algorithm. maybe they where moking me because i dont think openstreetmaps guy ignore how to write spirals but stil.. here it is.