No there was no LOD, the terrain layer meshes were used for blending the borders by using the alpha color of the outer vertices, invisible polygons on a layer were removed for the layer mesh. So there were several unique independent meshes that made the whole terrain. If you use a texture for blending the layers and a single terrain mesh, LOD should be doable like in a normal terrain.
Here is the basic layout for multilayer terrain with a shader (LOD-able, fast on decent Hardware):
- Lets say you have a single terrain mesh, and you have 3 layer textures you want to blend into the terrain.
- You also have one blending texture with RGB channels. The R part is for blending layer 1, B is for 2, and C is for 3.
- The blending texture must be UV mapped / stretched to the whole terrain. The layer textures use this UV coordinates but multiply/scale it in the shader to tile more than once.
- Assign the textures to the texture channels of the hardware, both the layer and the blending textures. This takes 4 texture channels in this example.
- Now use a shader to blend the layer textures. This is realy simple shader that just combines the layer textures based on the blending texture and scale the UV for the layer textures.
I haven't used that myself tho.