Add make_foundation option

test by /spawnstruct nether_outpost without being on complete
(covering the sidelen) solid ground

mods/MAPGEN/mcl_nether_fortresses/init.lua

@@ -16,6 +16,7 @@ mcl_structures.register_structure("nether_outpost",{
 	biomes = {"Nether","SoulsandValley","WarpedForest","CrimsonForest","BasaltDelta"},
 	sidelen = 15,
 	solid_ground = true,
+	make_foundation = true,
 	y_min = mcl_vars.mg_lava_nether_max - 1,
 	y_max = mcl_vars.mg_nether_max - 30,
 	filenames = { modpath.."/schematics/nether_outpost.mts" },

mods/MAPGEN/mcl_structures/api.lua

@@ -11,16 +11,21 @@ function mcl_structures.place_structure(pos, def, pr)
 	end
 	if def.solid_ground and def.sidelen then
 		local node = minetest.get_node(vector.offset(pos,1,1,0))
-		local solid = minetest.find_nodes_in_area(vector.offset(pos,-def.sidelen/2,-1,-def.sidelen/2),vector.offset(pos,def.sidelen/2,-1,def.sidelen/2),{"group:solid"})
+		local ground_p1 = vector.offset(pos,-def.sidelen/2,-1,-def.sidelen/2)
+		local ground_p2 = vector.offset(pos,def.sidelen/2,-1,def.sidelen/2)
+		local solid = minetest.find_nodes_in_area(ground_p1,ground_p2,{"group:solid"})
 		local air = minetest.find_nodes_in_area(vector.offset(pos,-def.sidelen/2,1,-def.sidelen/2),vector.offset(pos,def.sidelen/2,4,def.sidelen/2),{"air"})
 		if #solid < ( def.sidelen * def.sidelen ) or
 		#air < (def.sidelen * def.sidelen ) then
-			if logging then
+			if def.make_foundation then
-				minetest.log("warning","[mcl_structures] "..def.name.." at "..minetest.pos_to_string(pos).." not placed. No solid ground.")
+				minetest.bulk_set_node(minetest.find_nodes_in_area(ground_p1,vector.offset(ground_p2,0,-30,0),{"air"}),node)
+			else
+				if logging then
+					minetest.log("warning","[mcl_structures] "..def.name.." at "..minetest.pos_to_string(pos).." not placed. No solid ground.")
+				end
+				return false
 			end
-			return false
 		end
-		--minetest.bulk_set_node(solid,node)
 	end
 	if def.on_place and not def.on_place(pos,def,pr) then
 		if logging then