TFDi Design announced a new technology at the Flight Sim Show 2017 in Cosford called TrueGlass.
It is primarily a windscreen precipitation effect and wiper system that will also support icing and condensation in the future.
Essentially, it is a new custom solution to add rain effects to the windscreen of the aircraft. It supports speed transitions, wipers, as well as other weather variables other than rain. It works in Prepar3D version 4 but does not rely on the default rain effects in the simulator.
Based on user testing and reporting, the rain effects have little to no effect on simulator performance. This technology is available to developers to license on a per aircraft basis. For developers, it is an easily configurable file and minor model modification.
This will be a free update for the TFDi Design 717 and will be available via the Community Opt-In Beta for testing and verification, then we will be rolling it out in a future update to the rest of the license holders of the 717.