[chowells]

Almost completely irrelevant side note: atan2 is immensely useful because it actually does more than calculate the arctangent. It handles all the corner cases in converting a 2d vector to an angle. There's no chance of division by zero, it gets the answer into the correct quadrant automatically, and so on. Those things add up to an annoying series of if statements if all you have is an arctangent function.