add some support for special handling of leaf decay

settlements/buildings.lua

@@ -37,6 +37,22 @@ local function get_corner_pos(center_pos, schematic, rotation)
 	return corner1, corner2
 end
 
+local group_ids = {}
+local is_in_group = function(c_id, groupname)
+	local grouplist = group_ids[groupname]
+	if grouplist then
+		return grouplist[c_id]
+	end
+	grouplist = {}
+	for name, def in pairs(minetest.registered_nodes) do
+		if minetest.get_item_group(name, groupname) > 0 then
+			grouplist[minetest.get_content_id(name)] = true
+		end
+	end
+	group_ids[groupname] = grouplist
+	return grouplist[c_id]
+end
+
 -- function clear space above baseplate
 local function terraform(data, va, settlement_info)
 	local c_air = minetest.get_content_id(settlement_info.def.platform_air or "air")
@@ -56,7 +72,12 @@ local function terraform(data, va, settlement_info)
 		end
 		if build_platform == nil then
 			build_platform = true
-		end	
+		end
+
+		local skip_group_above = schematic_data.platform_ignore_group_above
+		if skip_group_above then
+			skip_group_above = skip_group_above:gsub("^group:", "")
+		end
 
 		local size = schematic_data.schematic.size
 		local pos = built_house.build_pos_min
@@ -82,8 +103,11 @@ local function terraform(data, va, settlement_info)
 						local p = {x=pos.x+xi, y=pos.y, z=pos.z+zi}
 						ground(p, data, va, c_shallow, c_deep)
 					elseif replace_air then
-						local vi = va:index(pos.x+xi, pos.y+yi, pos.z+zi)
-						data[vi] = c_air
+						local p = vector.new(pos.x+xi, pos.y+yi, pos.z+zi)
+						local vi = va:indexp(p)
+						if not (skip_group_above and is_in_group(data[vi], skip_group_above)) then
+							data[vi] = c_air
+						end
 					end
 				end
 			end
@@ -539,6 +563,16 @@ function settlements.place_building(vm, built_house, settlement_info)
 		force_place)
 end
 
+local trigger_timer_for_group = function(minp, maxp, nodenames)
+	if not nodenames then
+		return
+	end
+	local targets = minetest.find_nodes_in_area(minp, maxp, nodenames)
+	for _, pos in ipairs(targets) do
+		minetest.get_node_timer(pos):start(math.random(20, 120) / 10)
+	end
+end
+
 local data = {} -- for better memory management, use externally-allocated buffer
 settlements.generate_settlement_vm = function(vm, va, minp, maxp, existing_settlement_name)
 	vm:get_data(data)
@@ -568,6 +602,7 @@ settlements.generate_settlement_vm = function(vm, va, minp, maxp, existing_settl
 
 	-- evaluate settlement_info and initialize furnaces and chests
 	initialize_nodes(settlement_info)
+	trigger_timer_for_group(minp, maxp, settlement_info.def.trigger_timers_for_nodes)
 	return true
 end
 

settlements_medieval/init.lua

@@ -89,6 +89,10 @@ local townhall_schematic = {
 					-- So for example, 0.1 means at most 1 of these buildings in a 10-building settlement and 2 in a 20-building settlement.
 	replace_nodes_optional = true, -- If true, default:cobble will be replaced with a random wall material
 	initialize_node = initialize_node, -- allows additional post-creation actions to be executed on schematic nodes once they're constructed
+	platform_ignore_group_above = "group:leafdecay", -- causes special handling of nodes belonging to this group. If 
+		-- the node is in the space above the schematic being placed it will not be turned into air.
+		-- For leaves, make sure to add trigger_timers_for_nodes = "group:leafdecay" to the settlement settings to clean
+		-- up blobs of leaves that might be left over from trunks that have been removed.
 }
 local kingsmarket_schematic = {
 	name = "kingsmarket",
@@ -97,6 +101,7 @@ local kingsmarket_schematic = {
 	max_num = 0.1,
 	replace_nodes_optional = true,
 	initialize_node = initialize_node,
+	platform_ignore_group_above = "group:leafdecay",
 }
 
 -- list of schematics
@@ -107,6 +112,7 @@ local schematic_table = {
 		buffer = 2,
 		max_num = 0.045,
 		height_adjust = -2, -- adjusts the y axis of where the schematic is built, to allow for "basement" stuff
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "hut",
@@ -115,36 +121,42 @@ local schematic_table = {
 		max_num = 0.9,
 		replace_nodes_optional = true,
 		initialize_node = initialize_node,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "garden",
 		schematic = dofile(schem_path.."medieval_garden.lua"),
 		max_num = 0.1,
 		initialize_node = initialize_node,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "lamp",
 		schematic = dofile(schem_path.."medieval_lamp.lua"),
 		buffer = 3,
 		max_num = 0.05,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "tower",
 		schematic = dofile(schem_path.."medieval_tower.lua"),
 		buffer = 3,
 		max_num = 0.055,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "church",
 		schematic = dofile(schem_path.."medieval_church.lua"),
 		buffer = 2,
 		max_num = 0.075,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	{
 		name = "blacksmith",
 		schematic = dofile(schem_path.."medieval_blacksmith.lua"),
 		buffer = 2,
 		max_num = 0.050,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 	kingsmarket_schematic,
 	{
@@ -154,6 +166,7 @@ local schematic_table = {
 		max_num = 0.025,
 		replace_nodes_optional = true,
 		initialize_node = initialize_node,
+		platform_ignore_group_above = "group:leafdecay",
 	},
 }
 
@@ -170,7 +183,7 @@ local medieval_settlements = {
 		"default:silver_sand",
 		"default:snow_block",
 	},
-	
+
 	-- TODO: add a biome list. The tricky part here is, what if a biome list but not a surface materials list is provided?
 	-- How to find the surface, and how to know what to replace surface material nodes with in the schematic?
 
@@ -242,6 +255,11 @@ local medieval_settlements = {
 	end,
 
 	generate_book = generate_book,
+
+	-- This is a special-purpose property used for cleaning up leaf blobs that might have been left behind
+	-- when tree trunks got removed by buildings. It goes through every node in the mapchunk and sets the
+	-- node's timer going if it matches (using find_nodes_in_area).
+	trigger_timers_for_nodes = "group:leafdecay",
 }
 
 settlements.register_settlement("medieval", medieval_settlements)