Its interesting to see that the mirror reacts to the surroundings, but the effect is very dramatic. I wonder if they have made any custom shader or done some testing to get a working mirror. It could also be a problem with TrainGlassWeatherEffects shader if they have used that on the mirror. Not sure what loco that is, do they all act like that or only on repaints?
Thats the same romanian loco CFR 060 – EA 476-692-5 from Train Motion, that I started to fix) They all act like that. I would be more happy if it would be just texture, this flickering really annoying. Can you please point me where should I start my research?
Can you provide a download link? This needs looking into the GeoPcDx shader defs. If it's payware, the author should solve the issue. But maybe it was intended this way. Correct me if I'm wrong, but real mirrors would need portal rendering which is not possible in TS afaik.
I would ask Train Motion about the problem. First maybe do a clean install of the addon to check if any mods is causing this problem. Many devs have tried to make working mirrors in TS with custom shaders but to my knowledge nobody have had any success.
