Yup, I've been working a a shader using Nvidia's new SSDO algorithm http://kayru.org/articles/dssdo/
to approximate global illumination effects to simulate light and the new "Godray" shader. I've got it working to the point where Cloud is the global light can finally be controlled.https://developer.nvidia.com/sites/default/files/akamai/gameworks/events/gdc14/GDC_14_From%20Terrain%20to%20Godrays%20-%20Better%20Use%20of%20DirectX11CantlayTatarinov.pdf
Now the global light can be assigned to any character even invisible ones that can be placed strategically. But that's not the hurdle I'm trying to clear. I'm trying to find the best way for the light to effect the 2D backgrounds - and I think I've got it. I can actually single out a very specific color key and tell it one of three things. Does it Absorb Light? Generate Light? or Reflect Light.
Hard to imagine from this
informative video but I'm imagining real shadows cast and sun glare on the world map. Glowing objects will now shade the character, so on and so fourth. Anyway progress is slow but I made some headway tonight.https://youtu.be/BEjx0uiQavU
Sorry don't have much more to show y'all. The video depicts Cloud as a global light and you can see the light shifts with him, also the light peaks through the cracks in the vents. Now what this video unintentionally has is light beaming from everywhere that is because I assigned it to colors that are commonly found to test to see if the light was shifting. But with some tweaking to a scene maybe I can show you my overall vision better...
Using Sweet.fx to load a specific tone map when a scene loads seems like one possible way.