don't nil-out the recheck list, just empty it.

since nothing much is normally found outside that range anyway

only enqueue blocks that are within that range, or within
the range specfied by all of the mods that make generate_plant() calls,
whichever covers more volume.

API.txt

@@ -112,9 +112,9 @@ biome = {
 	depth_max = num,	-- If the object spawns on top of a water source, the
 						-- water must be at most this deep.  Defaults to 1.
 	min_elevation = num, -- Surface must be at this altitude or higher to
-						-- spawn at all.  Defaults to -31000...
+						 -- spawn at all.  Defaults to -16 meters.
-	max_elevation = num, -- ...but must be no higher than this altitude.
+	max_elevation = num, -- Surface must be no higher than this altitude.
-						-- Defaults to +31000.
+						 -- Defaults to +48.
 	near_nodes = {table}, -- List of nodes that must be somewhere in the
 						-- vicinity in order for the plant to spawn. Can also
 						-- be a string with a single node name.  If not
@@ -270,8 +270,8 @@ biome = {
 	depth = num,		-- How deep/thick of a layer the spawned-on node must
 						-- be.  Typically used for water.
 	min_elevation = num, -- Minimum elevation in meters/nodes.  Defaults to
-						-- -31000 (unlimited).
+						-- -16 meters.
-	max_elevation = num, -- Max elevation.  Defaults to +31000 (unlimited).
+	max_elevation = num, -- Max elevation.  Defaults to +48m.
 	near_nodes = {table}, -- what nodes must be in the general vicinity of the
 						-- object being spawned.
 	near_nodes_size = num, -- how wide of a search area to look for the nodes

README.md

@@ -25,4 +25,6 @@ It is primarily intended for mapgen v6, but it should work fine when used with m
 * biome_lib:find_valid_wall()
 * biome_lib:is_node_loaded()
 
-For a complete description of these functions as well as several of the internal variables within the mod, [read the API.txt document](https://raw.githubusercontent.com/minetest-mods/biome_lib/master/API.txt) included in this package.
+For a complete description of these functions as well as several of the internal variables within the mod, see `API.txt`.
+
+**Configuration:** This mod has several variables you can set in your `minetest.conf` to change things a bit, from the default nodes it uses, to the debug log level and the block queue behavior.  For a list with complete descriptions, see `settingtypes.txt`.

init.lua

@@ -33,6 +33,10 @@ biome_lib.actionslist_no_aircheck = {}
 biome_lib.surfaceslist_aircheck = {}
 biome_lib.surfaceslist_no_aircheck = {}
 
+-- the mapgen rarely creates useful surfaces outside this range, but mods can
+-- still specify a wider range if needed.
+biome_lib.mapgen_elevation_limit = { ["min"] = -16, ["max"] = 48 } 
+
 biome_lib.modpath = minetest.get_modpath("biome_lib")
 
 local function tableize(s)
@@ -72,8 +76,8 @@ biome_lib.default_grow_nodes =   c5 and tableize(c5) or {"default:dirt_with_gras
 
 biome_lib.debug_log_level = tonumber(minetest.settings:get("biome_lib_debug_log_level")) or 0
 
-local rr = tonumber(minetest.settings:get("biome_lib_queue_run_ratio")) or -100
+local rr = tonumber(minetest.settings:get("biome_lib_queue_ratio")) or -200
-biome_lib.queue_run_ratio = 100 - rr
+biome_lib.queue_ratio = 100 - rr
 biome_lib.entries_per_step = math.max(-rr, 1)
 
 -- the timer that manages the block timeout is in microseconds, but the timer
@@ -153,8 +157,8 @@ end
 
 function biome_lib:set_defaults(biome)
 	biome.seed_diff = biome.seed_diff or 0
-	biome.min_elevation = biome.min_elevation or -31000
+	biome.min_elevation = biome.min_elevation or biome_lib.mapgen_elevation_limit.min
-	biome.max_elevation = biome.max_elevation or 31000
+	biome.max_elevation = biome.max_elevation or biome_lib.mapgen_elevation_limit.max
 	biome.temp_min = biome.temp_min or 1
 	biome.temp_max = biome.temp_max or -1
 	biome.humidity_min = biome.humidity_min or 1
@@ -206,6 +210,9 @@ function biome_lib:register_generate_plant(biomedef, nodes_or_function_or_model)
 		biome_lib.dbg("Warning: Registered function call using deprecated string method: "..dump(nodes_or_function_or_model), 2)
 	end
 
+	biome_lib.mapgen_elevation_limit.min = math.min(biomedef.min_elevation or 0, biome_lib.mapgen_elevation_limit.min)
+	biome_lib.mapgen_elevation_limit.max = math.max(biomedef.max_elevation or 0, biome_lib.mapgen_elevation_limit.max)
+
 	if biomedef.check_air == false then 
 		biome_lib.dbg("Register no-air-check mapgen hook: "..dump(nodes_or_function_or_model), 3)
 		biome_lib.actionslist_no_aircheck[#biome_lib.actionslist_no_aircheck + 1] = { biomedef, nodes_or_function_or_model }
@@ -511,8 +518,13 @@ function biome_lib.generate_block(shutting_down)
 			biome_lib.pos_hash.surface_node_list = airflag
 				and minetest.find_nodes_in_area_under_air(minp, maxp, biome_lib.surfaceslist_aircheck)
 				or minetest.find_nodes_in_area(minp, maxp, biome_lib.surfaceslist_no_aircheck)
-			biome_lib.pos_hash.action_index = 1
+			if #biome_lib.pos_hash.surface_node_list == 0 then
-			if #biome_lib.pos_hash.surface_node_list > 0 then
+				biome_lib.dbg("Mapblock at "..minetest.pos_to_string(minp).." dequeued:  no detected surfaces.", 4)
+				table.remove(blocklog, 1)
+				biome_lib.pos_hash = nil
+				return
+			else
+				biome_lib.pos_hash.action_index = 1
 				biome_lib.dbg("Mapblock at "..minetest.pos_to_string(minp)..
 					" has "..#biome_lib.pos_hash.surface_node_list..
 					" surface nodes to work on (airflag="..dump(airflag)..")", 4)
@@ -559,7 +571,7 @@ end
 minetest.register_globalstep(function(dtime)
 	if not biome_lib.block_log[1] then return end -- the block log is empty
 
-	if math.random(100) > biome_lib.queue_run_ratio then return end
+	if math.random(100) > biome_lib.queue_ratio then return end
 	for s = 1, biome_lib.entries_per_step do
 		biome_lib.generate_block()
 	end
@@ -617,7 +629,7 @@ minetest.register_on_shutdown(function()
 	end
 
 	biome_lib.dbg("Stand by, purging the mapblock log "..
-		"(there are "..(#biome_lib.block_log + #biome_lib.block_recheck_list).." entries) ...", 0)
+		"(there are "..biome_lib.starting_count.." entries) ...", 0)
 
 	while #biome_lib.block_log > 0 do
 		biome_lib.generate_block(true)
@@ -626,6 +638,7 @@ minetest.register_on_shutdown(function()
 
 	if #biome_lib.block_recheck_list > 0 then
 		biome_lib.block_log = table.copy(biome_lib.block_recheck_list)
+		biome_lib.block_recheck_list = {}
 		while #biome_lib.block_log > 0 do
 			biome_lib.generate_block(true)
 			biome_lib.check_remaining_time()
@@ -853,6 +866,8 @@ end
 minetest.after(0, function()
 	biome_lib.dbg("Registered a total of "..(#biome_lib.surfaceslist_aircheck)+(#biome_lib.surfaceslist_no_aircheck).." surface types to be evaluated, spread", 0)
 	biome_lib.dbg("across "..#biome_lib.actionslist_aircheck.." actions with air-checking and "..#biome_lib.actionslist_no_aircheck.." actions without.", 0)
+	biome_lib.dbg("within an elevation range of "..biome_lib.mapgen_elevation_limit.min.." and "..biome_lib.mapgen_elevation_limit.max.." meters.", 0)
+
 end)
 
 biome_lib.dbg("[Biome Lib] Loaded", 0)

search_functions.lua

@@ -57,18 +57,26 @@ end
 
 minetest.register_on_generated(function(minp, maxp, blockseed)
 	local timestamp = minetest.get_us_time()
-	for x = 0, 4 do
+	for y = 0, 4 do
-		local minx = minp.x + x*16
+		local miny = minp.y + y*16
-		for y = 0, 4 do
-			local miny = minp.y + y*16
-			for z = 0, 4 do
-				local minz = minp.z + z*16
 
-				local bmin = {x=minx, y=miny, z=minz}
+		if miny >= biome_lib.mapgen_elevation_limit.min
-				local bmax = {x=minx + 15, y=miny + 15, z=minz + 15}
+		  and (miny + 15) <= biome_lib.mapgen_elevation_limit.max then
-				biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, true, timestamp }
+
-				biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, false, timestamp }
+			for x = 0, 4 do
+				local minx = minp.x + x*16
+
+				for z = 0, 4 do
+					local minz = minp.z + z*16
+
+					local bmin = {x=minx, y=miny, z=minz}
+					local bmax = {x=minx + 15, y=miny + 15, z=minz + 15}
+					biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, true, timestamp }
+					biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, false, timestamp }
+				end
 			end
+		else
+			biome_lib.dbg("Did not enqueue mapblocks at elevation "..miny.."m, they're out of range of any generate_plant() calls.", 4)
 		end
 	end
 	biome_lib.run_block_recheck_list = true

settingtypes.txt

@@ -28,7 +28,7 @@ biome_lib_default_ground_nodes (List of default root nodes) string default:dirt_
 # that many actions are executed on every single tick, skipping none.
 # More negative means more throughput, at the expense of lag.  On fast PC's,
 # a setting of between -500 and -2000 might be good.
-biome_lib_queue_run_ratio (Queue run ratio) int -100
+biome_lib_queue_ratio (Queue run ratio) int -200
 
 # Minetest's map generator allows neighboring areas to overflow into one
 # another, to create smooth terrain, but it often hands the map blocks that