By the way, is there some way to save each terrain splat painted layers to a texture map, sort of like alpha mask texture per file?
Viewing post in Fancy Procedural Terrain comments
Not in this tool. But notice the trees tweaking utility comes with source, including the B3D saving part.
Here I use a feature of copperlicht / webGL that allows to have two textures on one single mesh, whereby the mesh's vertex alpha value determines the visibility of the "top" texture. Additionally Vertex-RGB is used to taint seaground and add diffuse shade under trees.