I know that atan2 gives me the absolute angle of any vector. But it doesn't give a value from 0 to 360 degrees. Instead, it gives a value (if I'm not mistaken), between 0 and 180, or between 0 and ...
(Related, but somewhat different, to my previous question) How can I determine in a fragment shader if a fragment is in the shadow of a sphere? That is, if it is occluded by the sphere and is past ...