rainyday.js has this "rain on window" effect, i suppose it could be overlaid on top of krpano canvas (fixed to window), but that might look odd in some cases ?
projecting the "rainy window" on the entire sphere would also look kind of odd, like you were inside a plastic bubble inside the pano environment ?
rainyday.js does provide an interesting solution. I would like to add it to krpano except the blur effect.