This Blender [tutorial][1] by Andrew Price at 11:31 demonstrates what I am trying to achieve in Unreal Engine 4. (I tried to import the finished *.blend file into UE4 without success.)
I am working on a material Earth, which would be applied to a sphere. The material combines various Earth images including ground color, clouds, normal map, and night lights to create an Earth.
I have set the emissive property of the night lights image texture so that the city lights show on the night side of the earth. I would like to come up with some kind of a dynamic mask or some technique that will suppress the emissive property when that portion of the texture is lit by a directional light. (City lights aren’t visible from orbit on the day-side of the earth.)
In the Blender tutorial Price uses shader nodes to add a mix node with a grayscale node and a color ramp
http://www.blenderguru.com/wp-content/uploads/sites/3/2011/06/realistic-earth.png
Any pointers? Is this doable in Unreal Engine 4?
Regards,
James R. Mireles
Houston, TX