Then no, you won't be able to do that. The BGFX library needs to have its shaders pre-compiled. I would be really happy if Branimir made the BGFX library able to support runtime shader compilation, but I really don't see that happening anytime soon, and in any case, the BGFX library has nothing to do with MAME other than being what my shader code interfaces with, so it's none of our concern at the end of the day.