Add two underground structures.

init.lua

@@ -51,6 +51,7 @@ end
 ancient_world.registry = {}
 function ancient_world.register(name, def)
     local d = {
+        chance = 0.1,
         offset = {x=0, y=0, z=0},
         limit_y = {max = 31000, min = -31000},
     }
@@ -79,6 +80,11 @@ minetest.register_on_generated(function(minp, maxp, seed)
                     {x=minp.x, y=math.max(minp.y, def.limit_y.min), z=minp.z},
                     {x=maxp.x, y=math.min(maxp.y, def.limit_y.max), z=maxp.z},
                     def.on)
+            elseif def.type == "embedded" then
+                possible = minetest.find_nodes_in_area(
+                    {x=minp.x, y=math.max(minp.y, def.limit_y.min), z=minp.z},
+                    {x=maxp.x, y=math.min(maxp.y, def.limit_y.max), z=maxp.z},
+                    def.inside)
             end
             if #possible > 0 then
                 local r = table.copy(def.replacements or {})

structures.lua

@@ -1,7 +1,6 @@
 -- Old guardtower/outpost upon desert sand.
 ancient_world.register("ancient_world:ruin_desert_sand_1:desert_sand", {
     schematic = minetest.get_modpath("ancient_world") .. "/schematics/ruin_desert_sand_1.mts",
-    chance = 0.1,
     type = "decoration",
     offset = {
         x = 0,
@@ -21,7 +20,6 @@ ancient_world.register("ancient_world:ruin_desert_sand_1:desert_sand", {
 -- Normal sand.
 ancient_world.register("ancient_world:ruin_desert_sand_1:sand", {
     schematic = minetest.get_modpath("ancient_world") .. "/schematics/ruin_desert_sand_1.mts",
-    chance = 0.1,
     type = "decoration",
     offset = {
         x = 0,
@@ -44,7 +42,6 @@ ancient_world.register("ancient_world:ruin_desert_sand_1:sand", {
 -- Silver sand.
 ancient_world.register("ancient_world:ruin_desert_sand_1:silver_sand", {
     schematic = minetest.get_modpath("ancient_world") .. "/schematics/ruin_desert_sand_1.mts",
-    chance = 0.1,
     type = "decoration",
     offset = {
         x = 0,
@@ -64,3 +61,25 @@ ancient_world.register("ancient_world:ruin_desert_sand_1:silver_sand", {
     },
 })
 
+ancient_world.register("ancient_world:underground_hovel_1", {
+    schematic = minetest.get_modpath("ancient_world") .. "/schematics/underground_hovel_1.mts",
+    type = "decoration",
+    limit_y = {
+        max = -64,
+        min = -31000,
+    },
+    on = {"default:stone"},
+    random_replacements = {
+        ["ancient_world:placeholder_1"] = true,
+    },
+})
+
+ancient_world.register("ancient_world:underground_hovel_2", {
+    schematic = minetest.get_modpath("ancient_world") .. "/schematics/underground_hovel_2.mts",
+    type = "decoration",
+    limit_y = {
+        max = -64,
+        min = -31000,
+    },
+    on = {"default:stone"},
+})