An exploratory proof of concept of applying toggleable texlights onto `func_train`s and [in theory] `func_tracktrain`s.
Since the standard practice is to place func_[track]trains in a separate part of the map exclusively for lighting (also achievable with ZHLT's light_origin
property, it can theoretically be extended by also having switchable lights in that room, which then applies to the func_[track]train wherever they may be in the map.
The mechanism of turning the lights on or off is through `path_corner`s or `path_track`s, made to trigger the lights upon passing. Thus, carefully placing these path_* entities allows you to turn on/off lights on the train surface as they pass through the section.
A compelling use case for this would be to have trains pass through bright sunlight or environmental light and have their lighting respond in a somewhat convincing manner.
Caveat: You can only have a maximum of 4 toggleable lightmaps for any face of the train, per map.
EDIT: Also I want to point out that this is not a working example of the func_[track]trains throwing out light, but instead of light being thrown onto them instead. Prolly should've put a screenshot or 2. That's for later.