Something Wayne is very familiar with, but GinGin might not have seen yet in FG - the rain splash shader in action:
On the pad, but no lauch today, rain gently tapping on the windows.
Don't do this unless you're a professional (and even then...) - CAT-I approach to KSC, if MLS doesn't lock on, you're so screwed...
(still need to adjust glare and the splash vector, and I actually want to use it to render a crack in the glass for a systems abort mode where debris from SRBSep damages the window - but at least I've managed to put a correctly oriented surface in, which for me always seems to take longest...)