How about vector displaced decal w/ light/emission material inside? Does that work?
Didn't try it myself, but i've heard that light material and self illumination are working with decals just fine. I wouldn't be too much surprised to find that vector displacement is possible too :]
light emission, self illumination is working
vector displacement unfortunately not - all advanced displacement properties are taken from the base layer
light emission, self illumination is working
Light emission (using a light material as decal material) works only with restrictions:
The entire mesh receiving the decal gets turned into lights. Projecting a light material onto some car model creates 1:1 the triangle count of the car of lights. I expect that some hit depth/count parameter (if technically possible) could resolve this.
Directionallity does not work, seems to be zero regardless of the light materials value, same with other light material settings like visibility (which is obviously a technical restriction).
Backfaces get a pitch black decal. Here as well, hit count may solve it. No idea if it could be handled otherwise.
Good Luck
Yes, those are quite hard to solve efficiently, why I asked. I'd also like to see/know how glass, translucency, subsurface, layered, ray-switcher, shadow catcher... complex shaders behave.
Then, since decals are a hack (and almost exclusively used for exteriors), so could be shaders; are now any plans to expand some in a way that'll be more user friendly (uber-like) and handle decals better (ie. single sheet SSS, 2-sided, parallax mapping...)?
Finally, how soon or late can C4D users expect to taste it?
:)
Keep up the good work!