TrueGlass is a rain, icing, and fog effect for aircraft windshields in Prepar3D v4 exclusively. All rain drops are placed dynamically, and react to aircraft speed. Heavy rain will yield more drops and streaks than a light rain, which is quite noticeable when flying in and out of storms with a third party weather engine such as ActiveSky.
This is an entirely separate code base and implementation from the windshield rain effects present in Prepar3D v4.0. The effect must be implemented on a per-aircraft basis.
TrueGlass will be available first for our 717 in the near future. The goal is to work with other aircraft developers and implement TrueGlass into their products. Exact distribution and licensing details are still being worked out internally.
We originally started TrueGlass back in early 2016 in FSX, however the performance impact was too great when utilizing old technologies in that platform. P3D has introduced new technologies that have allowed us to achieve minimal to no performance impact.