Merge pull request 'Implement MC-like kelps in terms of growing and destroying' (#1354) from iliekprogrammar/MineClone2:kelp into master

Reviewed-on: https://git.minetest.land/MineClone2/MineClone2/pulls/1354

mods/ITEMS/REDSTONE/mesecons_mvps/init.lua

@@ -74,6 +74,7 @@ function mesecon.is_mvps_unsticky(node, pulldir, stack, stackid)
 end
 
 -- Functions to be called on mvps movement
+-- See also the callback
 function mesecon.register_on_mvps_move(callback)
 	mesecon.on_mvps_move[#mesecon.on_mvps_move+1] = callback
 end
@@ -405,17 +406,20 @@ mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_brown")
 mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_light_blue")
 mesecon.register_mvps_unsticky("mcl_colorblocks:glazed_terracotta_pink")
 
+-- Includes node heat when moving them
 mesecon.register_on_mvps_move(mesecon.move_hot_nodes)
 
--- Check for falling after moving node
 mesecon.register_on_mvps_move(function(moved_nodes)
 	for i = 1, #moved_nodes do
 		local moved_node = moved_nodes[i]
+		-- Check for falling after moving node
 		mesecon.on_placenode(moved_node.pos, moved_node.node)
 		minetest.after(0, function()
 			minetest.check_for_falling(moved_node.oldpos)
 			minetest.check_for_falling(moved_node.pos)
 		end)
+
+		-- Callback for on_mvps_move stored in nodedef
 		local node_def = minetest.registered_nodes[moved_node.node.name]
 		if node_def and node_def.mesecon and node_def.mesecon.on_mvps_move then
 			node_def.mesecon.on_mvps_move(moved_node.pos, moved_node.node,

mods/ITEMS/mcl_ocean/init.lua

@@ -1,3 +1,5 @@
+mcl_ocean = {}
+
 -- Prismarine (includes sea lantern)
 dofile(minetest.get_modpath(minetest.get_current_modname()).."/prismarine.lua")
 

mods/ITEMS/mcl_ocean/kelp.lua

@@ -1,71 +1,494 @@
+-- TODO: whenever it becomes possible to fully implement kelp without the
+-- plantlike_rooted limitation, please update accordingly.
+--
+-- TODO: In MC, you can't actually destroy kelp by bucket'ing water in the middle.
+-- However, because of the plantlike_rooted hack, we'll just allow it for now.
+
 local S = minetest.get_translator("mcl_ocean")
 local mod_doc = minetest.get_modpath("doc") ~= nil
 
--- List of supported surfaces for seagrass and kelp
-local surfaces = {
-	{ "dirt", "mcl_core:dirt" },
-	{ "sand", "mcl_core:sand", 1 },
-	{ "redsand", "mcl_core:redsand", 1 },
-	{ "gravel", "mcl_core:gravel", 1 },
-}
+--------------------------------------------------------------------------------
+-- local-ify runtime functions
+--------------------------------------------------------------------------------
+-- objects
+local mt_registered_items = minetest.registered_items
+local mt_registered_nodes = minetest.registered_nodes
 
-local function get_kelp_top(pos, node)
-	local size = math.ceil(node.param2 / 16)
-	local pos_water = table.copy(pos)
-	pos_water.y = pos_water.y + size
-	return pos_water, minetest.get_node(pos_water)
+-- functions
+local mt_log = minetest.log
+local mt_add_item = minetest.add_item
+local mt_get_item_group = minetest.get_item_group
+local mt_get_node = minetest.get_node
+local mt_get_node_level = minetest.get_node_level
+local mt_get_node_max_level = minetest.get_node_max_level
+local mt_get_node_or_nil = minetest.get_node_or_nil
+local mt_get_node_timer = minetest.get_node_timer
+local mt_get_meta = minetest.get_meta
+local mt_hash_node_position = minetest.hash_node_position
+local mt_set_node = minetest.set_node
+local mt_swap_node = minetest.swap_node
+local mt_pos_to_string = minetest.pos_to_string
+local mt_is_protected = minetest.is_protected
+local mt_record_protection_violation = minetest.record_protection_violation
+
+local mt_is_creative_enabled = minetest.is_creative_enabled
+local mt_sound_play = minetest.sound_play
+
+local math_min = math.min
+local math_max = math.max
+local math_ceil = math.ceil
+local math_floor = math.floor
+local math_random = math.random
+local string_format = string.format
+local table_copy = table.copy
+local table_insert = table.insert
+
+-- DEBUG: functions
+-- local log = minetest.log
+-- local chatlog = minetest.chat_send_all
+
+--------------------------------------------------------------------------------
+-- Kelp API
+--------------------------------------------------------------------------------
+
+local kelp = {}
+mcl_ocean.kelp = kelp
+
+-- Kelp minimum and maximum age. Once reached the maximum, kelp no longer grows.
+kelp.MIN_AGE = 0
+kelp.MAX_AGE = 25
+
+-- Tick interval (in seconds) for updating kelp.
+kelp.TICK = 0.2
+
+-- Tick interval (in seconds) to store kelp meta.
+kelp.META_TICK = 2
+
+-- Max age queue length
+kelp.MAX_AGE_QUEUE = 20
+
+-- The average amount of growth for kelp in a day is 2.16 (https://youtu.be/5Bp4lAjAk3I)
+-- Normally, a day lasts 20 minutes, meaning kelp.next_grow() is executed
+-- 1200 / TICK times. Per tick probability = (216/100) / (1200/TICK)
+-- NOTE: currently, we can't exactly use the same type of randomness MC does, because
+-- it has multiple complicated sets of PRNGs.
+-- NOTE: Small loss of precision, should be 10 to preserve it.
+-- kelp.ROLL_GROWTH_PRECISION = 10
+-- kelp.ROLL_GROWTH_NUMERATOR = 216 * kelp.TICK * kelp.ROLL_GROWTH_PRECISION
+-- kelp.ROLL_GROWTH_DENOMINATOR = 100 * 1200 * kelp.ROLL_GROWTH_PRECISION
+kelp.ROLL_GROWTH_PRECISION = 1
+kelp.ROLL_GROWTH_NUMERATOR = 216 * kelp.TICK
+kelp.ROLL_GROWTH_DENOMINATOR = 100 * 1200
+
+-- Sounds used to dig and place kelp.
+kelp.leaf_sounds = mcl_sounds.node_sound_leaves_defaults()
+
+-- Pool storing nodetimers
+kelp.timers_pool = {}
+
+-- Pool storing age, indexed by pos_hash.
+kelp.age_pool = {}
+
+-- Queue(List) of hashed positions to save their ages.
+-- Invalid ones may still persist in this queue.
+kelp.age_queue = {}
+-- Stores only valid positions of each hashed postiions.
+kelp.age_queue_pos = {}
+
+
+-- is age in the growable range?
+function kelp.is_age_growable(age)
+	return age >= 0 and age < kelp.MAX_AGE
 end
 
-local function get_submerged(node_water)
-	local def_water = minetest.registered_nodes[node_water.name]
-	-- Submerged in water?
-	if minetest.get_item_group(node_water.name, "water") then
-		if def_water.liquidtype == "source" then
-			return "source"
-		elseif def_water.liquidtype == "flowing" then
-			return "flowing"
-		end
+
+-- Is this water?
+-- Returns the liquidtype, if indeed water.
+function kelp.is_submerged(node)
+	if mt_get_item_group(node.name, "water") ~= 0 then
+		-- Expected only "source" and "flowing" from water liquids
+		return mt_registered_nodes[node.name].liquidtype
 	end
 	return false
 end
 
-local function grow_param2_step(param2, snap_into_grid)
-	local old_param2 = param2
-	param2 = param2 + 16
-	if param2 > 240 then
-		param2 = 240
+
+-- Is the water downward flowing?
+-- (kelp can grow/be placed inside downward flowing water)
+function kelp.is_downward_flowing(pos, node, pos_above, node_above, __is_above__)
+	-- Function params: (pos[, node]) or (node, pos_above) or (node, node_above)
+	local node = node or mt_get_node(pos)
+
+	local result = (math_floor(node.param2 / 8) % 2) == 1
+	if not (result or __is_above__) then
+		-- If not, also check node above.
+		-- (this is needed due a weird quirk in the definition of "downwards flowing"
+		-- liquids in Minetest)
+		local pos_above = pos_above or {x=pos.x,y=pos.y+1,z=pos.z}
+		local node_above = node_above or mt_get_node(pos_above)
+		result = kelp.is_submerged(node_above)
+			or kelp.is_downward_flowing(nil, node_above, nil, nil, true)
 	end
-	if snap_into_grid and (param2 % 16 ~= 0) then
-		param2 = param2 - (param2 % 16)
-	end
-	return param2, param2 ~= old_param2
+	return result
 end
 
-local function kelp_check_place(pos_above, node_above, def_above)
-	if minetest.get_item_group(node_above.name, "water") == 0 then
+
+-- Will node fall at that position?
+-- This only checks if a node would fall, meaning that node need not be at pos.
+function kelp.is_falling(pos, node, is_falling, pos_bottom, node_bottom, def_bottom)
+	-- Optional params: is_falling, pos_bottom, node_bottom, def_bottom
+
+	-- NOTE: Modified from check_single_for_falling in builtin.
+	-- Please update accordingly.
+	local nodename = node.name
+
+	if is_falling == false or
+		is_falling == nil and mt_get_item_group(nodename, "falling_node") == 0 then
 		return false
 	end
-	local can_place = false
-	if (def_above.liquidtype == "source") then
-		can_place = true
-	elseif (def_above.liquidtype == "flowing") then
-		-- Check if bit 3 (downwards flowing) is set
-		can_place = (math.floor(node_above.param2 / 8) % 2) == 1
-		if not can_place then
-			-- If not, also check node above (this is needed due a weird quirk in the definition of
-			-- "downwards flowing" liquids in Minetest)
-			local node_above_above = minetest.get_node({x=pos_above.x,y=pos_above.y+1,z=pos_above.z})
-			local naa_def = minetest.registered_nodes[node_above_above.name]
-			can_place = naa_def.liquidtype == "source"
-			if not can_place then
-				can_place = (naa_def.liquidtype == "flowing") and ((math.floor(node_above_above.param2 / 8) % 2) == 1)
+
+	local pos_bottom = pos_bottom or {x = pos.x, y = pos.y - 1, z = pos.z}
+	-- get_node_or_nil: Only fall if node below is loaded
+	local node_bottom = node_bottom or mt_get_node_or_nil(pos_bottom)
+	local nodename_bottom = node_bottom.name
+	local def_bottom = def_bottom or node_bottom and mt_registered_nodes[nodename_bottom]
+	if not def_bottom then
+		return false
 	end
+
+	local same = nodename == nodename_bottom
+	-- Let leveled nodes fall if it can merge with the bottom node
+	if same and def_bottom.paramtype2 == "leveled" and
+			mt_get_node_level(pos_bottom) <
+			mt_get_node_max_level(pos_bottom) then
+		return true
 	end
+
+	-- Otherwise only if the bottom node is considered "fall through"
+	if not same and
+			(not def_bottom.walkable or def_bottom.buildable_to) and
+			(mt_get_item_group(nodename, "float") == 0 or
+			def_bottom.liquidtype == "none") then
+		return true
 	end
-	return can_place
+
+	return false
 end
 
-local function kelp_on_place(itemstack, placer, pointed_thing)
+
+-- Roll whether to grow kelp or not.
+function kelp.roll_growth(numerator, denominator)
+	-- Optional params: numerator, denominator
+	return math_random(denominator or kelp.ROLL_GROWTH_DENOMINATOR) <= (numerator or kelp.ROLL_GROWTH_NUMERATOR)
+end
+
+
+-- Roll initial age for kelp.
+function kelp.roll_init_age(min, max)
+	-- Optional params
+	return math_random(min or kelp.MIN_AGE, (max or kelp.MAX_AGE)-1)
+end
+
+
+-- Converts param2 to kelp height.
+function kelp.get_height(param2)
+	return math_floor(param2 / 16)
+end
+
+
+-- Obtain pos and node of the tip of kelp.
+function kelp.get_tip(pos, param2)
+	-- Optional params: param2
+	local height = kelp.get_height(param2 or mt_get_node(pos).param2)
+	local pos_tip = {x=pos.x, y=pos.y, z=pos.z}
+	pos_tip.y = pos_tip.y + height + 1
+	return pos_tip, mt_get_node(pos_tip), height
+end
+
+
+-- Obtain position of the first kelp unsubmerged.
+function kelp.find_unsubmerged(pos, node, height)
+	-- Optional params: node, height
+	local node = node or mt_get_node(pos)
+	local height = height or kelp.get_height(node.param2)
+
+	local walk_pos = {x=pos.x, z=pos.z}
+	local y = pos.y
+	for i=1,height do
+		walk_pos.y = y + i
+		local walk_node = mt_get_node(walk_pos)
+		if not kelp.is_submerged(walk_node) then
+			return walk_pos, walk_node, height, i
+		end
+	end
+	return nil, nil, height, height
+end
+
+
+-- Obtain next param2.
+function kelp.next_param2(param2)
+	return param2+16 - param2 % 16
+end
+
+
+-- Stores age from kelp.age_queue* into their respective meta
+function kelp.store_meta()
+	local count = 0
+	for _ in pairs(kelp.age_queue_pos) do
+		count = count + 1
+	end
+	-- chatlog(string_format("Storing age metadata: %d in queue", #kelp.age_queue))
+	-- chatlog(string_format("Storing age metadata: %d valid in queue", count))
+	for i=1,#kelp.age_queue do
+		local pos_hash = kelp.age_queue[i]
+		local pos = kelp.age_queue_pos[pos_hash]
+		-- queued hashes may no longer point to a valid pos, e.g. kelp is destroyed.
+		if pos then
+			mt_get_meta(pos):set_int("mcl_ocean:kelp_age", kelp.age_pool[pos_hash])
+		end
+	end
+	kelp.age_queue = {}
+	kelp.age_queue_pos = {}
+end
+
+
+-- Store and queue a kelp's age to be saved into meta later.
+function kelp.store_age(age, pos, pos_hash)
+	-- Watched params: pos
+	-- Optional params: pos_hash
+	local pos_hash = pos_hash or mt_hash_node_position(pos)
+
+	kelp.age_pool[pos_hash] = age
+	if not kelp.age_queue_pos[pos_hash] then
+		table_insert(kelp.age_queue, pos_hash)
+		kelp.age_queue_pos[pos_hash] = pos
+		return true, pos_hash
+	end
+
+	return false, pos_hash
+end
+
+
+-- Initialise a kelp's age.
+function kelp.init_age(pos, age, pos_hash, meta)
+	-- Watched params: pos
+	-- Optional params: age, pos_hash, meta
+	local pos_hash = pos_hash or mt_hash_node_position(pos)
+	local meta = meta or mt_get_meta(pos)
+
+	local age = age
+	if age then
+		kelp.store_age(age, pos, pos_hash)
+	elseif not meta:contains("mcl_ocean:kelp_age") then
+		age = kelp.roll_init_age()
+		kelp.store_age(age, pos, pos_hash)
+	else
+		age = meta:get_int("mcl_ocean:kelp_age")
+		if not kelp.age_pool[pos_hash] then
+			kelp.age_pool[pos_hash] = age
+		end
+	end
+
+	return age, pos_hash, meta
+end
+
+
+-- Initialise kelp nodetimer.
+function kelp.init_timer(pos, pos_hash)
+	-- Optional params: pos_hash
+	local pos_hash = pos_hash or mt_hash_node_position(pos)
+
+	local timer = kelp.timers_pool[pos_hash]
+	if not timer then
+		timer = mt_get_node_timer(pos)
+		kelp.timers_pool[pos_hash] = timer
+	end
+	if not timer:is_started() then
+		timer:start(kelp.TICK)
+	end
+
+	return pos_hash
+end
+
+
+-- Apply next kelp height.
+function kelp.next_height(pos, node, pos_tip, node_tip, submerged, downward_flowing)
+	-- Modified params: node
+	-- Optional params: node, set_node, pos_tip, node_tip, submerged, downward_flowing
+	local node = node or mt_get_node(pos)
+	local pos_tip = pos_tip
+	local node_tip = node_tip or (pos_tip and mt_get_node(pos_tip))
+	if not pos_tip then
+		pos_tip,node_tip = kelp.get_tip(pos)
+	end
+	local downward_flowing = downward_flowing or
+		(submerged or kelp.is_submerged(node_tip)
+		 and kelp.is_downward_flowing(pos_tip, node_tip))
+
+	-- Liquid source: Grow normally.
+	node.param2 = kelp.next_param2(node.param2)
+	mt_swap_node(pos, node)
+
+	-- Flowing liquid: Grow 1 step, but also turn the tip node into a liquid source.
+	if downward_flowing then
+		local alt_liq = mt_registered_nodes[node_tip.name].liquid_alternative_source
+		if alt_liq then
+			mt_set_node(pos_tip, {name=alt_liq})
+		end
+	end
+
+	return node, pos_tip, node_tip, submerged, downward_flowing
+end
+
+
+-- Grow next kelp.
+function kelp.next_grow(age, pos, node, pos_hash, pos_tip, node_tip, submerged, downward_flowing)
+	-- Watched params: pos
+	-- Modified params: node
+	-- Optional params: node, pos_hash, pos_tip, node_tip, submerged, downward_flowing
+	local node = node or mt_get_node(pos)
+	local pos_hash = pos_hash or mt_hash_node_position(pos)
+	local pos_tip = pos_tip
+	local node_tip = node_tip or (pos_tip and mt_get_node(pos_tip))
+	if not pos_tip then
+		pos_tip,node_tip = kelp.get_tip(pos)
+	end
+
+	-- New kelp must also be submerged in water.
+	local downward_flowing = downward_flowing or kelp.is_downward_flowing(pos_tip, node_tip)
+	if not (submerged or kelp.is_submerged(node_tip)) then
+		return
+	end
+
+	kelp.next_height(pos, node, pos_tip, node_tip, submerged, downward_flowing)
+
+	return kelp.store_age(age, pos, pos_hash), node, pos_hash, pos_tip, node_tip, submerged, downward_flowing
+end
+
+
+-- Drops the items for detached kelps.
+function kelp.detach_drop(pos, param2)
+	-- Optional params: param2
+	local height = kelp.get_height(param2 or mt_get_node(pos).param2)
+	local y = pos.y
+	local walk_pos = {x=pos.x, z=pos.z}
+	for i=1,height do
+		walk_pos.y = y+i
+		mt_add_item(walk_pos, "mcl_ocean:kelp")
+	end
+	return true
+end
+
+
+-- Detach the kelp at dig_pos, and drop their items.
+-- Synonymous to digging the kelp.
+-- NOTE: this is intended for whenever kelp truly becomes segmented plants
+-- instead of rooted to the floor. Don't try to remove dig_pos.
+function kelp.detach_dig(dig_pos, pos, node, drop)
+	-- Optional params: drop
+
+	local param2 = node.param2
+	-- pos.y points to the surface, offset needed to point to the first kelp.
+	local new_height = dig_pos.y - (pos.y+1)
+
+	-- Digs the entire kelp.
+	if new_height <= 0 then
+		if drop then
+			kelp.detach_drop(dig_pos, param2)
+		end
+		mt_set_node(pos, {
+			name=mt_registered_nodes[node.name].node_dig_prediction,
+			param=node.param,
+			param2=0 })
+
+	-- Digs the kelp beginning at a height.
+	else
+		if drop then
+			kelp.detach_drop(dig_pos, param2 - new_height)
+		end
+		mt_swap_node(pos, {name=node.name, param=node.param, param2=16*new_height})
+	end
+end
+
+
+--------------------------------------------------------------------------------
+-- Kelp callback functions
+--------------------------------------------------------------------------------
+
+function kelp.surface_on_dig(pos, node, digger)
+	kelp.detach_dig(pos, pos, node, true)
+end
+
+
+function kelp.surface_after_dig_node(pos, node)
+	return mt_set_node(pos, {name=registred_nodes[node.name].node_dig_prediction})
+end
+
+
+function kelp.surface_on_timer(pos)
+	local node = mt_get_node(pos)
+	local pos_hash
+
+	-- Update detahed kelps
+	local dig_pos = kelp.find_unsubmerged(pos, node)
+	if dig_pos then
+		pos_hash = mt_hash_node_position(pos)
+		mt_sound_play(mt_registered_nodes[node.name].sounds.dug, { gain = 0.5, pos = dig_pos }, true)
+		kelp.detach_dig(dig_pos, pos, node, true)
+		kelp.store_age(kelp.roll_init_age(), pos, pos_hash)
+	end
+
+	-- Grow kelp on chance
+	if kelp.roll_growth() then
+		pos_hash = pos_hash or mt_hash_node_position(pos)
+		local age = kelp.age_pool[pos_hash]
+		if kelp.is_age_growable(age) then
+			kelp.next_grow(age+1, pos, node, pos_hash)
+		end
+	end
+
+	return true
+end
+
+function kelp.surface_on_construct(pos)
+	local pos_hash = mt_hash_node_position(pos)
+	kelp.init_age(pos, nil, pos_hash)
+	kelp.init_timer(pos, pos_hash)
+end
+
+
+function kelp.surface_on_destruct(pos)
+	local node = mt_get_node(pos)
+	local pos_hash = mt_hash_node_position(pos)
+
+	-- on_falling callback. Activated by pistons for falling nodes too.
+	if kelp.is_falling(pos, node) then
+		kelp.detach_drop(pos, node.param2)
+	end
+
+	-- Removes position from queue
+	kelp.age_queue_pos[pos_hash] = nil
+end
+
+
+
+function kelp.surface_on_mvps_move(pos, node, oldpos, nodemeta)
+	-- Pistons moving falling nodes will have already activated on_falling callback.
+	kelp.detach_dig(pos, pos, node, mt_get_item_group(node.name, "falling_node") ~= 1)
+end
+
+
+-- NOTE: Old ABM implementation.
+-- local function surface_unsubmerged_abm(pos, node)
+-- 	local dig_pos = find_unsubmerged(pos, node)
+-- 	if dig_pos then
+-- 		detach_dig(dig_pos, pos, node, true)
+-- 	end
+-- 	return true
+-- end
+
+
+function kelp.kelp_on_place(itemstack, placer, pointed_thing)
 	if pointed_thing.type ~= "node" or not placer then
 		return itemstack
 	end
@@ -73,133 +496,142 @@ local function kelp_on_place(itemstack, placer, pointed_thing)
 	local player_name = placer:get_player_name()
 	local pos_under = pointed_thing.under
 	local pos_above = pointed_thing.above
-	local node_under = minetest.get_node(pos_under)
-	local node_above = minetest.get_node(pos_above)
-	local def_under = minetest.registered_nodes[node_under.name]
-	local def_above = minetest.registered_nodes[node_above.name]
+	local node_under = mt_get_node(pos_under)
+	local nu_name = node_under.name
+	local def_under = mt_registered_nodes[nu_name]
 
+	-- Allow rightclick to override place.
 	if def_under and def_under.on_rightclick and not placer:get_player_control().sneak then
 		return def_under.on_rightclick(pos_under, node_under,
 				placer, itemstack, pointed_thing) or itemstack
 	end
 
-	if minetest.is_protected(pos_under, player_name) or
-			minetest.is_protected(pos_above, player_name) then
-		minetest.log("action", player_name
+	-- Protection
+	if mt_is_protected(pos_under, player_name) or
+			mt_is_protected(pos_above, player_name) then
+		mt_log("action", player_name
 			.. " tried to place " .. itemstack:get_name()
 			.. " at protected position "
-			.. minetest.pos_to_string(pos_under))
-		minetest.record_protection_violation(pos_under, player_name)
+			.. mt_pos_to_string(pos_under))
+		mt_record_protection_violation(pos_under, player_name)
 		return itemstack
 	end
 
-	local grow_kelp = false
-	-- Select a kelp node when placed on surface node
-	if node_under.name == "mcl_core:dirt" then
-		node_under.name = "mcl_ocean:kelp_dirt"
-	elseif node_under.name == "mcl_core:sand" then
-		node_under.name = "mcl_ocean:kelp_sand"
-	elseif node_under.name == "mcl_core:redsand" then
-		node_under.name = "mcl_ocean:kelp_redsand"
-	elseif node_under.name == "mcl_core:gravel" then
-		node_under.name = "mcl_ocean:kelp_gravel"
-	elseif minetest.get_item_group(node_under.name, "kelp") == 1 then
-		-- Place kelp on kelp = grow kelp by 1 node length
-		node_under.param2, grow_kelp = grow_param2_step(node_under.param2)
-		if not grow_kelp then
-			return itemstack
-		end
-	else
-		return itemstack
-	end
-	local submerged = false
-	if grow_kelp then
-		-- Kelp placed on kelp ...
-		-- Kelp can be placed on top of another kelp to make it grow
-		if pos_under.y >= pos_above.y or pos_under.x ~= pos_above.x or pos_under.z ~= pos_above.z then
-			-- Placed on side or below node, abort
-			return itemstack
-		end
-		-- New kelp top must also be submerged in water
-		local top_pos, top_node = get_kelp_top(pos_under, node_under)
-		local top_def = minetest.registered_nodes[top_node.name]
-		submerged = kelp_check_place(top_pos, top_node, top_def)
-		if not submerged then
-			-- Not submerged in water, abort
-			return itemstack
-		end
-	else
-		-- New kelp placed ...
+
+	local pos_tip, node_tip, def_tip, new_kelp
+	-- Kelp must also be placed on the top/tip side of the surface/kelp
 	if pos_under.y >= pos_above.y then
-			-- Placed on side or below node, abort
 		return itemstack
 	end
-		-- Kelp can be placed inside a water source or water flowing downwards on top of a surface node
-		local can_place = kelp_check_place(pos_above, node_above, def_above)
-		if not can_place then
+
+	-- When placed on kelp.
+	if mt_get_item_group(nu_name, "kelp") == 1 then
+		pos_tip,node_tip = kelp.get_tip(pos_under, node_under.param2)
+		def_tip = mt_registered_nodes[node_tip.name]
+
+	-- When placed on surface.
+	else
+		new_kelp = false
+		for _,surface in pairs(kelp.surfaces) do
+			if nu_name == surface.nodename then
+				node_under.name = "mcl_ocean:kelp_" ..surface.name
+				node_under.param2 = 0
+				new_kelp = true
+				break
+			end
+		end
+		-- Surface must support kelp
+		if not new_kelp then
 			return itemstack
 		end
-		node_under.param2 = minetest.registered_items[node_under.name].place_param2 or 16
+
+		pos_tip = pos_above
+		node_tip = mt_get_node(pos_above)
+		def_tip = mt_registered_nodes[node_tip.name]
 	end
-	-- Place or grow kelp
-	local def_node = minetest.registered_items[node_under.name]
+
+	-- New kelp must also be submerged in water.
+	local downward_flowing = kelp.is_downward_flowing(pos_tip, node_tip)
+	local submerged = kelp.is_submerged(node_tip)
+	if not submerged then
+		return itemstack
+	end
+
+	-- Play sound, place surface/kelp and take away an item
+	local def_node = mt_registered_items[nu_name]
 	if def_node.sounds then
-		minetest.sound_play(def_node.sounds.place, { gain = 0.5, pos = pos_under }, true)
+		mt_sound_play(def_node.sounds.place, { gain = 0.5, pos = pos_under }, true)
 	end
-	minetest.set_node(pos_under, node_under)
-	if not minetest.is_creative_enabled(player_name) then
+	kelp.next_height(pos_under, node_under, pos_tip, node_tip, def_tip, submerged, downward_flowing)
+	if not mt_is_creative_enabled(player_name) then
 		itemstack:take_item()
 	end
 
+	-- Initialize age and timer when it's a new kelp
+	local pos_hash = mt_hash_node_position(pos_under)
+	if new_kelp then
+		kelp.init_age(pos_under, nil, pos_hash)
+		kelp.init_timer(pos_under, pos_hash)
+	else
+		kelp.store_age(kelp.roll_init_age(), pos_under, pos_hash)
+	end
+
 	return itemstack
 end
 
-local get_kelp_height = function(param2)
-	return math.floor(param2 / 16)
+
+function kelp.lbm_register_nodetimer(pos, node)
+	local pos_hash = mt_hash_node_position(pos)
+	kelp.init_age(pos, nil, pos_hash)
+	kelp.init_timer(pos, pos_hash)
 end
 
-minetest.register_craftitem("mcl_ocean:kelp", {
-	description = S("Kelp"),
-	_tt_help = S("Grows in water on dirt, sand, gravel"),
-	_doc_items_create_entry = false,
-	inventory_image = "mcl_ocean_kelp_item.png",
-	wield_image = "mcl_ocean_kelp_item.png",
-	on_place = kelp_on_place,
-	groups = { deco_block = 1 },
-})
 
--- Kelp nodes: kelp on a surface node
+local gstep_time = 0
+function kelp.globalstep(dtime)
+	if #kelp.age_queue > kelp.MAX_AGE_QUEUE then
+		kelp.store_meta()
+	end
 
-for s=1, #surfaces do
-	local def = minetest.registered_nodes[surfaces[s][2]]
-	local alt
-	if surfaces[s][3] == 1 then
-		alt = surfaces[s][2]
+	gstep_time = gstep_time + dtime
+	if gstep_time < kelp.META_TICK then
+		return
 	end
-	local sounds = table.copy(def.sounds)
-	local leaf_sounds = mcl_sounds.node_sound_leaves_defaults()
-	sounds.dig = leaf_sounds.dig
-	sounds.dug = leaf_sounds.dug
-	sounds.place = leaf_sounds.place
-	local tt_help, doc_longdesc, doc_img, desc
-	if surfaces[s][1] == "dirt" then
-		doc_longdesc = S("Kelp grows inside water on top of dirt, sand or gravel.")
-		desc = S("Kelp")
-		doc_create = true
-		doc_img = "mcl_ocean_kelp_item.png"
-	else
-		doc_create = false
+	gstep_time = 0
+
+	if #kelp.age_queue > 0 then
+		kelp.store_meta()
 	end
-	minetest.register_node("mcl_ocean:kelp_"..surfaces[s][1], {
-		_doc_items_entry_name = desc,
-		_doc_items_longdesc = doc_longdesc,
-		_doc_items_create_entry = doc_create,
-		_doc_items_image = doc_img,
+end
+
+
+function kelp.on_shutdown()
+	if #kelp.age_queue > 0 then
+		kelp.store_meta()
+	end
+end
+
+--------------------------------------------------------------------------------
+-- Kelp registration API
+--------------------------------------------------------------------------------
+
+-- List of supported surfaces for seagrass and kelp.
+kelp.surfaces = {
+	{ name="dirt",    nodename="mcl_core:dirt",    },
+	{ name="sand",    nodename="mcl_core:sand",    },
+	{ name="redsand", nodename="mcl_core:redsand", },
+	{ name="gravel",  nodename="mcl_core:gravel",  },
+}
+kelp.registered_surfaces = {}
+
+-- Commented properties are the ones obtained using register_kelp_surface.
+-- If you define your own properties, it overrides the default ones.
+kelp.surface_deftemplate = {
 	drawtype = "plantlike_rooted",
 	paramtype = "light",
 	paramtype2 = "leveled",
 	place_param2 = 16,
-		tiles = def.tiles,
+	--tiles = def.tiles,
 	special_tiles = {
 		{
 		image = "mcl_ocean_kelp_plant.png",
@@ -207,7 +639,7 @@ for s=1, #surfaces do
 		tileable_vertical = true,
 		}
 	},
-		inventory_image = "("..def.tiles[1]..")^mcl_ocean_kelp_item.png",
+	--inventory_image = "("..def.tiles[1]..")^mcl_ocean_kelp_item.png",
 	wield_image = "mcl_ocean_kelp_item.png",
 	selection_box = {
 		type = "fixed",
@@ -216,40 +648,99 @@ for s=1, #surfaces do
 			{ -0.5, 0.5, -0.5, 0.5, 1.5, 0.5 },
 		},
 	},
-		groups = { dig_immediate = 3, deco_block = 1, plant = 1, kelp = 1, falling_node = surfaces[s][3] },
-		sounds = sounds,
-		node_dig_prediction = surfaces[s][2],
-		after_dig_node = function(pos)
-			minetest.set_node(pos, {name=surfaces[s][2]})
-		end,
-		on_dig = function(pos, node, digger)
-			-- Drop kelp as item; item count depends on height
-			local dname = ""
-			if digger then
-				dname = digger:get_player_name()
-			end
-			local creative = minetest.is_creative_enabled(dname)
-			if not creative then
-				minetest.add_item({x=pos.x, y=pos.y+1, z=pos.z}, "mcl_ocean:kelp "..get_kelp_height(node.param2))
-			end
-			minetest.node_dig(pos, node, digger)
-		end,
+	-- groups.falling_node = is_falling,
+	groups = { dig_immediate = 3, deco_block = 1, plant = 1, kelp = 1, },
+	--sounds = sounds,
+	--node_dig_prediction = nodename,
+	on_construct = kelp.surface_on_construct,
+	on_destruct = kelp.surface_on_destruct,
+	on_dig = kelp.surface_on_dig,
+	after_dig_node = kelp.surface_after_dig_node,
+	on_timer = kelp.surface_on_timer,
+	mesecon = { on_mvps_move = kelp.surface_on_mvps_move, },
 	drop = "", -- drops are handled in on_dig
-		_mcl_falling_node_alternative = alt,
+	--_mcl_falling_node_alternative = is_falling and nodename or nil,
 	_mcl_hardness = 0,
 	_mcl_blast_resistance = 0,
-	})
+}
 
-	if mod_doc and surfaces[s][1] ~= "dirt" then
-		doc.add_entry_alias("nodes", "mcl_ocean:kelp_dirt", "nodes", "mcl_ocean:kelp_"..surfaces[s][1])
+-- Commented properties are the ones obtained using register_kelp_surface.
+kelp.surface_docs = {
+	-- entry_id_orig = nodename,
+	_doc_items_entry_name = S("Kelp"),
+	_doc_items_longdesc = S("Kelp grows inside water on top of dirt, sand or gravel."),
+	--_doc_items_create_entry = doc_create,
+	_doc_items_image = "mcl_ocean_kelp_item.png",
+}
+
+-- Creates new surfaces.
+-- NOTE: surface_deftemplate will be modified in-place.
+function kelp.register_kelp_surface(surface, surface_deftemplate, surface_docs)
+	local name = surface.name
+	local nodename = surface.nodename
+	local def = mt_registered_nodes[nodename]
+	local def_tiles = def.tiles
+
+	local surfacename = "mcl_ocean:kelp_"..name
+	local surface_deftemplate = surface_deftemplate or kelp.surface_deftemplate -- Optional param
+
+	local doc_create = surface.doc_create or false
+	local surface_docs = surface_docs or kelp.surface_docs -- Optional param
+
+	if doc_create then
+		surface_deftemplate._doc_items_entry_name = surface_docs._doc_items_entry_name
+		surface_deftemplate._doc_items_longdesc = surface_docs._doc_items_longdesc
+		surface_deftemplate._doc_items_create_entry = true
+		surface_deftemplate._doc_items_image = surface_docs._doc_items_image
+		-- Sets the first surface as the docs' entry ID
+		if not surface_docs.entry_id_orig then
+			surface_docs.entry_id_orig = nodename
 		end
+	elseif mod_doc then
+		doc.add_entry_alias("nodes", surface_docs.entry_id_orig, "nodes", surfacename)
+	end
+
+	local sounds = table_copy(def.sounds)
+	sounds.dig = kelp.leaf_sounds.dig
+	sounds.dug = kelp.leaf_sounds.dug
+	sounds.place = kelp.leaf_sounds.place
+
+	surface_deftemplate.tiles = surface_deftemplate.tiles or def_tiles
+	surface_deftemplate.inventory_image = surface_deftemplate.inventory_image or "("..def_tiles[1]..")^mcl_ocean_kelp_item.png"
+	surface_deftemplate.sounds = surface_deftemplate.sound or sounds
+	local falling_node = mt_get_item_group(nodename, "falling_node")
+	surface_deftemplate.node_dig_prediction = surface_deftemplate.node_dig_prediction or nodename
+	surface_deftemplate.groups.falling_node = surface_deftemplate.groups.falling_node or falling_node
+	surface_deftemplate._mcl_falling_node_alternative = surface_deftemplate._mcl_falling_node_alternative or (falling_node and nodename or nil)
+
+	minetest.register_node(surfacename, surface_deftemplate)
 end
 
+-- Kelp surfaces nodes ---------------------------------------------------------
+
+-- Dirt must be registered first, for the docs
+kelp.register_kelp_surface(kelp.surfaces[1], table_copy(kelp.surface_deftemplate), kelp.surface_docs)
+for i=2, #kelp.surfaces do
+	kelp.register_kelp_surface(kelp.surfaces[i], table_copy(kelp.surface_deftemplate), kelp.surface_docs)
+end
+
+-- Kelp item -------------------------------------------------------------------
+
+minetest.register_craftitem("mcl_ocean:kelp", {
+	description = S("Kelp"),
+	_tt_help = S("Grows in water on dirt, sand, gravel"),
+	_doc_items_create_entry = false,
+	inventory_image = "mcl_ocean_kelp_item.png",
+	wield_image = "mcl_ocean_kelp_item.png",
+	on_place = kelp.kelp_on_place,
+	groups = { deco_block = 1 },
+})
+
 if mod_doc then
-	doc.add_entry_alias("nodes", "mcl_ocean:kelp_dirt", "craftitems", "mcl_ocean:kelp")
+	doc.add_entry_alias("nodes", kelp.surface_docs.entry_id_orig, "craftitems", "mcl_ocean:kelp")
 end
 
--- Dried kelp stuff
+-- Dried kelp ------------------------------------------------------------------
 
 -- TODO: This is supposed to be eaten very fast
 minetest.register_craftitem("mcl_ocean:dried_kelp", {
@@ -264,13 +755,13 @@ minetest.register_craftitem("mcl_ocean:dried_kelp", {
 	_mcl_saturation = 0.6,
 })
 
+
 local mod_screwdriver = minetest.get_modpath("screwdriver") ~= nil
 local on_rotate
 if mod_screwdriver then
 	on_rotate = screwdriver.rotate_3way
 end
 
-
 minetest.register_node("mcl_ocean:dried_kelp_block", {
 	description = S("Dried Kelp Block"),
 	_doc_items_longdesc = S("A decorative block that serves as a great furnace fuel."),
@@ -310,32 +801,35 @@ minetest.register_craft({
 	burntime = 200,
 })
 
--- Grow kelp
-minetest.register_abm({
-	label = "Kelp growth",
+-- Global registration ------------------------------------------------------------------------
+
+minetest.register_lbm({
+	label = "Kelp initialise",
+	name = "mcl_ocean:kelp_init",
 	nodenames = { "group:kelp" },
-	interval = 45,
-	chance = 12,
-	catch_up = false,
-	action = function(pos, node, active_object_count, active_object_count_wider)
-		local grown
-		-- Grow kelp by 1 node length if it would grow inside water
-		node.param2, grown = grow_param2_step(node.param2, true)
-		local top, top_node = get_kelp_top(pos, node)
-		local submerged = get_submerged(top_node)
-		if grown then
-			if submerged == "source" then
-				-- Liquid source: Grow normally
-				minetest.set_node(pos, node)
-			elseif submerged == "flowing" then
-				-- Flowing liquid: Grow 1 step, but also turn the top node into a liquid source
-				minetest.set_node(pos, node)
-				local def_liq = minetest.registered_nodes[top_node.name]
-				local alt_liq = def_liq and def_liq.liquid_alternative_source
-				if alt_liq then
-					minetest.set_node(top, {name=alt_liq})
-				end
-			end
-		end
-	end,
+	run_at_every_load = true, -- so old kelps are also initialised
+	action = kelp.lbm_register_nodetimer,
 })
+
+
+minetest.register_globalstep(kelp.globalstep)
+minetest.register_on_shutdown(kelp.on_shutdown)
+
+-- NOTE: Old ABM implementation.
+-- minetest.register_abm({
+-- 	label = "Kelp drops",
+-- 	nodenames = { "group:kelp" },
+-- 	interval = 1.0,
+-- 	chance = 1,
+-- 	catch_up = false,
+-- 	action = surface_unsubmerged_abm,
+-- })
+--
+-- minetest.register_abm({
+-- 	label = "Kelp growth",
+-- 	nodenames = { "group:kelp" },
+-- 	interval = 45,
+-- 	chance = 12,
+-- 	catch_up = false,
+-- 	action = grow_abm,
+-- })