I think zuikki1, and probably many others, deserve to get an answer.
Correct me if I'm wrong, but please do reply.
The rx thing started as an experiment, the single purpose was to add newer shader version support to RBR (ie. the "night mod") but later things got complicated because the original mesh format is not adequate so one thing got to another and instead of just replacing shaders it ended up rendering the whole track. The goal wasn't, at any moment, to replace or support every single feature from RBR, surely it would be awesome it that would happen, but as things are now the original goal was acheived.
For those complaining about "missing features": i'm quite tired of reading it and frankly i kinda wish i've never made the plugin, because it seems the things would be much easier for everybody, but since is here please remember rx was always free and it was never advertised as something more than it is; there is nobody more aware than me about what the plugin can and can't do and ofcourse i wish all the features to be supported. If for any reason you're not happy with how the things are now well, you know the cliché, don't like don't use it.
As about future of the plugin i have no clue whatsoever, all i can say is curently i don't even have the game installed and it's been more than 3 years since i've opened RBR just to have fun so take this as an answer.
I can't say anything about BTB as i'm not involved but frankly i would not be surprised for a second if RBR support would be dropped all together because the whole thing, despite being fun and interesting for a while, it turned into a world of pain for Piddy as well - and i do feel guilty and ashamed as i realise is very possible he could have been in a better situation now if the whole rx thing never existed.
All in all, the plugin is free, there are demos available for both rx tracks and BTB and there are atleast 3 forums dedicated so anybody can easily learn whatever there is to know about the whole thing first hand so there is no misrepresenting that i'm aware of... i recall threads like this being started here before and at RSC and even at BHM, always the same people, same questions and same answers so forgive me saying it's getting old and i really don't see the point.
Have a good day, i certainly don't have one.
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