How to do wrap lighting

Is there a way for me to make a material (either using nodes or normal materials) that has wrap lighting - where the diffuse light also shines on the back side of the material. I’ve tried using the ramp shader, but that maps the left side of the ramp to where the angle-of-incidence is 90deg, so I can’t control the shading of the back side.

Some background:
I’m looking to use Blender to render out (many) cubemaps for prebaked lighting for human skin. This will be pulled into a realtime shader in the Unity game engine (where spec etc is added).

Sorry if this is a noob post, but I’ve been fighting for a few days and I just couldn’t get it to work. I DID consider adding some darklights to the back side of the proxy object, but we have so many light sources that it would be impractical.

Any ideas?

Naturally I figured out a solution after posting: Have 3 toon shaders with max smoothness. This makes each cover approx 1/3 of the AOI range. Then I used ‘size’ to offset them, and added all of them together in the shader graph. This gave me a grayscale gradient I could feed into a color ramp for full control.

Are you talking about sub-surface scattering? If so, search on SSS here and find what others have tried to do.
I’m not up on it, so not sure if you’ve used a similar technique, but it sounds interesting. Can you post a couple of shots?

Let me try to elaborate: This is one part of a fake SSS effect for in-game usage.

Basically, I bake a cubemap by rendering a sphere in blender - basically a light probe. This we then use to light all ingame models. For skin, I need a light probe that exhibits lighting turning a bit reddish on the back side of the object (part of the SSS effect). Later I’ll be brighning it up a bit around the edges, as well as adding spec highlights for perspiration.

Below are what I’ve got so far:
1st picture are shot with ‘cloudy’ illumination (lots of skylight, weak sun), the second is no ambient, one directional at full strength.

In each image there are 3 versions: A basic diffuse shader, a hacked version of nvidia’s dawn shader and the new one I’m working on.

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Interesting, thanks! Looks like your method really brightens up the object. The reddish backlight sounds like a good idea.
I understand the SSS concept, but haven’t done the research of true SSS nor fake methods to tell if something is accurate or not.
How accurate is the Cloudy picture? It looks almost identical to the Sun picture.
Speaking of which, why is there no ambient on the Sun image, shouldn’t there be even more ambient since there will be more light reflected from images? Or is it set like that due to balance between the relative direct & ambient levels?

The one-light no ambient is mainly for debugging purposes. I just have a dropdown where I can select from a list of lighting environments. (dawn, sunset, cloudy, sunlight, night, debug). These are Cloudy & debug.