2019-07-04 lunar landscape material

source(The pictures in the text need to climb over the wall to see):
Essential Material Concepts - An introductory document on UE4 Materials and how they work.
Materials - Controlling the appearance of surfaces in the world using shaders.
Landscape Materials - Setting up materials to work with Landscape terrains.

Blend Type	Function
LB Weight Blend	Use if you have layers coming in from an external program, like World Machine, or if you wanted to be able to paint any layer independent of one another without worrying about layer order.
LB Alpha Blend	Use if you want to paint in detail and if you want a defined layer order. For example, painting snow over rock and grass will occlude them, but erasing snow will reveal rock and grass beneath it.
LB Height Blend	This is the same as LB_WeightBlend but also adds detail to the transition between layers based on a height map. This allows, for example, dirt to appear in the gaps between rocks at the layer transition point, instead of just smoothly blending between rock and dirt.