Dynamic Rain Overlay

https://youtu.be/jdUY3IxLnS0

The Dynamic Rain Overlay system is a quick way to add dynamic
rain effects to your materials. Simply hook this material function
into your existing materials and edit Global Rain Amount material
parameter to control the amount of rain.

Comes with both animated and static impact droplets. And a macro
wetness / puddle overlay.

Tiling amounts, and intensity are all exposed, and can be easily
tweaked for each material. Puddles will automatically smooth the
normals of the geometry underneath, but this can easily be tweaked
to the user’s liking. In addition, world space tiling can be used
on static objects to prevent seams on UV borders.

All inputs are optional, and the material function has default
values. You would only need to override this values when
necessary.