TFDi Design, the developers that have brought us SmartCARS and the 717 have just announced their latest product. It is going by the name of TrueGlass and will provide rain droplet effects for P3D v4 only. TFDi have created custom rain drops which look to have turned out very nicely.
The droplets will interact with the windscreen wipers, being removed when wipers are turned on. They will also interact with speed changes and move off the windscreen as speed increases.
At this stage, it only works with TFDi’s 717 but they are in contact with other developers to make it compatible.