Only carve through ground nodes

init.lua

@@ -486,27 +486,34 @@ function internal.mapgen(minp, maxp, blockseed, vm, va)
     -- they're in.
     local sva = VoxelArea(minp, maxp)
     local data = vm:get_data()
+    local ground = { [ minetest.CONTENT_AIR ] = false }
 
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.ceilings, sva, "node_roof"
+        data, va, used_biomes, classified_nodes.ceilings, sva, "node_roof",
+        ground
     )
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.contents, sva, "node_air"
+        data, va, used_biomes, classified_nodes.contents, sva, "node_air",
+        ground
     )
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.floors, sva, "node_floor"
+        data, va, used_biomes, classified_nodes.floors, sva, "node_floor",
+        ground
     )
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.walls, sva, "node_wall"
+        data, va, used_biomes, classified_nodes.walls, sva, "node_wall",
+        ground
     )
 
     -- Place floor decorations
     -- In case the dust has not been defined, place air nodes first
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.floor_decos, sva, "node_air"
+        data, va, used_biomes, classified_nodes.floor_decos, sva, "node_air",
+        ground
     )
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.floor_decos, sva, "node_dust"
+        data, va, used_biomes, classified_nodes.floor_decos, sva, "node_dust",
+        ground
     )
     local claimed_floor = internal.write_simple_floor_decorations(
         data, va, used_biomes, classified_nodes.floor_decos, sva
@@ -514,7 +521,8 @@ function internal.mapgen(minp, maxp, blockseed, vm, va)
 
     -- Place ceiling decorations
     internal.write_classified_node(
-        data, va, used_biomes, classified_nodes.ceiling_decos, sva, "node_air"
+        data, va, used_biomes, classified_nodes.ceiling_decos, sva, "node_air",
+        ground
     )
     local claimed_ceiling = internal.write_simple_ceiling_decorations(
         data, va, used_biomes, classified_nodes.ceiling_decos, sva
@@ -533,21 +541,6 @@ function internal.mapgen(minp, maxp, blockseed, vm, va)
     vm:write_to_map()
 end
 
--- Place items
-function internal.place_node_on_data(data, i, name)
-    if name == nil then
-        return
-    end
-
-    local node_id = minetest.get_content_id(name)
-
-    if node_id == nil then
-        return
-    end
-
-    data[i] = node_id
-end
-
 -- Register a new biome
 function internal.register_biome(biome)
     biome = internal.clean_biome_def(biome)
@@ -606,7 +599,7 @@ function internal.verticality_noise_params()
     }
 end
 
-function internal.write_classified_node(vm_data, va, used_biomes, classified_nodes, small_va, biome_key)
+function internal.write_classified_node(vm_data, va, used_biomes, classified_nodes, small_va, biome_key, ground_content_nodes)
     local default_biome = internal.default_biome()
 
     local biome_to_id = {}
@@ -635,7 +628,17 @@ function internal.write_classified_node(vm_data, va, used_biomes, classified_nod
         local content_id = biome_to_id[biome]
 
         if content_id ~= "" then
-            vm_data[va:index(pos.x, pos.y, pos.z)] = content_id
+            local vi = va:index(pos.x, pos.y, pos.z)
+            local vm_node = vm_data[vi]
+
+            if ground_content_nodes[vm_node] == nil then
+                local name = minetest.get_name_from_content_id(content_id)
+                ground_content_nodes[vm_node] = minetest.registered_nodes[name].is_ground_content or true
+            end
+
+            if ground_content_nodes[vm_node] then
+                vm_data[vi] = content_id
+            end
         end
     end
 end

lua/register.lua

@@ -68,9 +68,9 @@ ns_caves.register_decoration({
     deco_type = "simple",
     place_on = "ceiling",
     fill_ratio = 0.025,
-    decoration = "mcl_bamboo:bamboo_block",
+    decoration = "mcl_colorblocks:concrete_green",
     height = 3,
-    height_max = 16,
+    height_max = 7,
 })
 
 ns_caves.register_decoration({
@@ -79,6 +79,6 @@ ns_caves.register_decoration({
     fill_ratio = 0.025,
     decoration = "mcl_bamboo:bamboo_block",
     height = 3,
-    height_max = 16,
+    height_max = 7,
 })