I’m trying to think how to approach a “wetness” shader creation. Basically, if it rains, every surface facing up would get “wet”, meaning dropping its roughness way down. This is probably achievable by using world Z-up position, much like in many of the snow shaders out there. Now for the tricky part, I would like to also include rain drop ripples added on top of that. I can imagine one ripple being a normal map flipbook texture, for instance, but I have no idea how to multiply that with z-up vector part and make it random in position/scale so it feels natural.
Would be great to hear any ideas or see some examples of how to do that.