Just dropping this one here. I know that nVidia is pushing for real time Ray Tracing graphics with their new RTX cards, and how these will make reflections, colour mixing and shadows appear true to life. According to them, reflections could only be done by resorting to the use of reflection maps, which TS uses for the shiny shaders, but... How is TSW managing to do real time reflections almost 2 years prior to RTX being launched? On Pascal cards nonetheless?
These are standard screen-space reflections, nothing special. It doesn't calculate it in a physically correct way, it just takes already rendered part of the screen (on the left in your shot) and uses it as a reflection on a train, warping it according to hull unevenness and various other mesh features. Do you wonder why HST nose lacks reflections? Because there's nothing rendered beyond left side of screen, so there's nothing to reflect. That's very popular method, because it's cheap in terms of performance and produces good reflections majority of the time, unless you specifically looking at them. On the other hand, raytracing produces physically correct reflections and lighting/shading for entire scene, including things beyond your screen, and it's expensive as hell. Here's a detailed article on SSR [pdf]
That's the reason why we don't have working mirrors on the CSX locos, the reflections on the trains are just mirrored like Jef-F explained. If there where allready raytracing we had working mirrors. I hope raytracing will be in the future added to TSW.
Well, you can make mirrors without raytracing, but you need to setup virtual viewports for every mirror, render everything they "see" just like the main camera view and project onto mirrors' surface... takes time for poking around and, obviously, some performance hit.
It'll be a few years until raytracing is cheap enough (both computationally and in terms of hardware) that a majority of players can use it. Regarding mirrors, raytracing would be useful in that a fixed camera would be hard to program (think how depending on where you stop changes how many doors of the train you could see). I can think of a bodge to approximate the required camera angle in UE4 but raytracing is the best method. For CCTV it's very easy to just set up a camera for each set of doors (which makes it pretty easy to check the doors on underground and certain UK routes).
