The object I'm trying to model is made mostly of a material which requires subsurface scattering. Parts of the object are coated by a thin metal foil. I'd like this foil to properly darken the material that surrounds it, but so far the only approach that has worked is by creating real geometry to cast this shadow. Is there a better way to set this up? Ultimately I was hoping to use a texture to specify which areas are metal foil and which ones aren't.
Here's an example:
The bottom left circle selects the metal foil via a texture which drives a Mix Shader node. The top left star is a face with the foil material assigned to it. The circle on the right is a separate object very close to the surface of the main plane, and is the only one that correctly darkens the subsurface scattered light.
I've also noticed that EEVEE darkens the scattered light correctly at least when a whole face has the metal film material applied:
I suppose it makes sense that the Mix Shader approach does not create a shadow. Is there another way to use a texture to select between these two materials?
