update readme.

replace the placeholder api functionality for checking whether air flows
through a node, with something that relies on a dedicated group (instead
of a hard-coded list in the api code).

README.md

@@ -20,10 +20,12 @@ you can turn a log into planks by pummeling it with stone. there must be air on
 
 you can grow a tree by placing a dirty node (dirt or grass) on top of a nut. this will create a sapling, which will grow into something vaguely resembling a tree (including roots in the ground). note that there's currently no way to get nuts, so you'll have to use cheats for now if you want trees.
 
-you can create dirt by pummeling leaves with leaves.
+you can create dirt by placing leaves next to dirt or grass; eventually they'll start decomposing. this does not work for growing leaves (which are unobtainable as an item anyways).
+
+you start running over time as you move. this also makes you jump higher (although it does not make you take less fall damage).
 
 # warning
 
 updates might introduce changes that are not backwards-compatible. i'll probably use [semantic versioning](https://semver.org/) eventually.
 
-i'll try to make sure new code includes ways of converting stuff in old worlds to work with the new code, but can't guarantee it.
+i'll try to make sure new code includes ways of converting stuff in old worlds to work with the new code, but don't guarantee it.

mods/bg_api/increasing_abm.lua

@@ -0,0 +1,31 @@
+function blockgame.register_increasing_abm (def)
+	local id = def.id or "unknown"
+	local label = def.label or "unlabeled"
+	local nodenames = def.nodenames or {}
+	local neighbors = def.neighbors or {}
+	local interval = def.interval or 60
+	local chance = def.chance or 10
+	-- TODO: fully validate def, make sure it has the necessary functions specified.
+	
+	blockgame.register_abm({
+		label = label,
+		nodenames = nodenames,
+		neighbors = neighbors,
+		interval = interval,
+		chance = chance,
+		action = function (pos, node)
+			local meta = minetest.get_meta(pos)
+			local value = meta:get_int(id) or 0
+			local data = {
+				value = value,
+			}
+
+			value = def.rate(pos, node, data)
+			meta:set_int(id, value)
+
+			if not def.check(pos, node, data) then return end
+
+			def.action(pos, node, data)
+		end,
+	})
+end

mods/bg_api/init.lua

@@ -17,5 +17,7 @@ load_file("util_node")
 load_file("wrappers")
 
 load_file("random_tick")
+load_file("loose_nodes")
+load_file("increasing_abm")
 
 load_file("cleanup")

mods/bg_api/loose_nodes.lua

@@ -0,0 +1,63 @@
+-- TODO: collapse nodes when the node under them is removed.
+
+local function attempt_collapse_at (pos)
+	local below = pos + blockgame.vector.dirs.down
+	if minetest.get_node(below).name ~= "air" then return end
+
+	minetest.spawn_falling_node(pos)
+end
+
+local function place_loose_node (itemstack, placer, pointed)
+	local result = minetest.item_place(itemstack, placer, pointed)
+	attempt_collapse_at(pointed.above)
+	return result
+end
+
+-- collapse nodes that somehow managed to stay in the air.
+blockgame.register_abm({
+	label = "collapse collapsible nodes",
+	nodenames = {"group:loose"},
+	neighbors = {"air"},
+	interval = 15,
+	chance = 1,
+	action = attempt_collapse_at,
+})
+
+local function attempt_settle_at (pos)
+	local below = pos + blockgame.vector.dirs.down
+	if minetest.get_node(below).name == "air" then return end
+
+	local def = minetest.registered_nodes[minetest.get_node(pos).name]
+	minetest.set_node(pos, {name = def.stable_version})
+end
+
+-- settle nodes that are still (in the future, it will take some time for loose nodes that are still to settle).
+blockgame.register_abm({
+	label = "settle collapsible nodes",
+	nodenames = {"group:loose"},
+	interval = 30,
+	chance = 10,
+	action = attempt_settle_at,
+})
+
+
+
+function blockgame.register_loose_version (name)
+	local def = minetest.registered_nodes[name]
+	if not def then return false end
+
+	local groups = {}
+	for key, value in pairs(def.groups) do
+		groups[key] = value
+	end
+	groups.loose = 1
+
+	blockgame.register_node(name .. "_loose", {
+		description = "Loose " .. def.description,
+		tiles = def.tiles, -- temporary
+		groups = groups,
+		on_place = place_loose_node,
+		stable_version = name,
+	})
+	return true
+end

mods/bg_api/util_node.lua

@@ -11,20 +11,13 @@ end
 
 
 
--- probably temporary; will probably use groups for this later.
-local air_flowable = {
-	"air",
-	"bg_tree:leaves",
-	"bg_tree:leaves_alive",
-}
-
 function blockgame.air_flows_through (pos, node)
 	node = node or minetest.get_node(pos)
 	local node_name = node.name
-	for _, name in pairs(air_flowable) do
-		if name == node_name then return true end
-	end
-	return false
+
+	if node_name == "air" then return true end
+
+	return minetest.get_item_group(node_name, "air_flowable") > 0
 end
 
 
@@ -55,3 +48,14 @@ function blockgame.random_walk (data)
 	end
 	return pos
 end
+
+
+
+function blockgame.get_neighbors (pos, neighborhood)
+	neighborhood = neighborhood or blockgame.vector.dirs
+	local neighbors = {}
+	for _, dir in pairs(neighborhood) do
+		table.insert(neighbors, pos + dir)
+	end
+	return neighbors
+end

mods/bg_grass/init.lua

@@ -1,2 +0,0 @@
-load_file("grow")
-load_file("death")

mods/bg_grass/mod.conf

@@ -1,3 +0,0 @@
-name = bg_grass
-description = adds grass spreading and related mechanics to blockgame.
-depends = bg_terrain, bg_api

mods/bg_terrain/init.lua

@@ -3,4 +3,7 @@ local modname = minetest.get_current_modname()
 load_file("node")
 load_file("biome")
 
+load_file("grass_grow")
+load_file("grass_death")
+
 load_file("cleanup")

mods/bg_terrain/node.lua

@@ -30,7 +30,12 @@ blockgame.register_node(modname .. ":grass", {
 	},
 	drop = modname .. ":dirt",
 })
+
 blockgame.reg_simple_node("dirt", "Dirt", {
 	cracky = 3,
 	dirty = 1,
 })
+
+blockgame.register_loose_version(modname .. ":dirt")
+blockgame.register_loose_version(modname .. ":grass")
+blockgame.register_loose_version(modname .. ":cobblestone")

mods/bg_tree/decompose.lua

@@ -0,0 +1,48 @@
+local modname = minetest.get_current_modname()
+local api = blockgame.tree
+local vec = blockgame.vector
+
+-- NODE NAMES
+
+local leaves = modname .. ":leaves"
+local leaves_decomposing = modname .. ":leaves_decomposing"
+
+-- END OF NODE NAMES
+
+blockgame.register_increasing_abm({
+	id = "bg_tree:begin_decompose",
+	label = "decompose leaves",
+	nodenames = {leaves},
+	neighbors = {"group:dirty"},
+	interval = 15,
+	chance = 4,
+	rate = function (pos, node, data)
+		return data.value + math.random(4, 6)
+	end,
+	check = function (pos, node, data)
+		return data.value >= 20
+	end,
+	action = function (pos, node, data)
+		minetest.set_node(pos, {name = leaves_decomposing})
+	end,
+})
+
+blockgame.register_increasing_abm({
+	id = "bg_tree:decompose",
+	label = "decompose leaves",
+	nodenames = {leaves_decomposing},
+	neighbors = {"group:dirty"},
+	interval = 30,
+	chance = 10,
+	rate = function (pos, node, data)
+		-- TODO: decompose faster depending on surrounding dirty nodes & other decomposing leaves.
+		-- can probably do that with a flood fill that counts up a "score" depending on the nodes it encounters.
+		return data.value + math.random(1, 9)
+	end,
+	check = function (pos, node, data)
+		return data.value >= 30
+	end,
+	action = function (pos, node, data)
+		minetest.set_node(pos, {name = "bg_terrain:dirt"})
+	end,
+})

mods/bg_tree/grow.lua

@@ -64,7 +64,6 @@ blockgame.register_abm({
 	neighbors = {"group:dirty", log_alive},
 	interval = 15,
 	chance = 4,
-	catch_up = true,
 	action = function (pos, node, active_object_count, active_object_count_wider)
 		local below = vec.get_below(pos)
 
@@ -75,9 +74,6 @@ blockgame.register_abm({
 			end
 		end
 
-		if blockgame.chance(2) then
-			extend_leaves_from(pos)
-		end
 		if blockgame.chance(2) then
 			extend_leaves_from(pos)
 		end
@@ -87,10 +83,6 @@ blockgame.register_abm({
 			local target = pos + side
 
 			blockgame.attempt_place(target, {name = log_alive})
-
-			if blockgame.chance(2) then
-				extend_leaves_from(target)
-			end
 		end
 
 		if blockgame.chance(4) then

mods/bg_tree/grow_leaves.lua

@@ -0,0 +1,37 @@
+local modname = minetest.get_current_modname()
+local api = blockgame.tree
+local vec = blockgame.vector
+
+-- NODE NAMES
+
+local log = modname .. ":log"
+local log_alive = modname .. ":log_alive"
+local leaves = modname .. ":leaves"
+local leaves_alive = modname .. ":leaves_alive"
+local root = modname .. ":root"
+
+-- END OF NODE NAMES
+
+local max_grow_distance = 2
+
+blockgame.register_abm({
+	label = "grow leaves",
+	nodenames = {leaves_alive},
+	neighbors = {log_alive, leaves_alive},
+	interval = 15,
+	chance = 8,
+	action = function (pos, node)
+		-- TODO: give leaves energy over time, that they spend when creating new leaves.
+		local meta = minetest.get_meta(pos)
+		local distance = meta:get_int("leaf_distance") or 1
+		if distance >= max_grow_distance then return end
+
+		local neighbors = blockgame.get_neighbors(pos)
+		for _, target in pairs(neighbors) do
+			if blockgame.chance(6) then
+				blockgame.attempt_place(target, {name = leaves_alive})
+				minetest.get_meta(target):set_int("leaf_distance", distance + 1)
+			end
+		end
+	end,
+})

mods/bg_tree/init.lua

@@ -1,5 +1,11 @@
 load_file("api")
-load_file("decoration")
+
 load_file("node")
+load_file("decoration")
+
 load_file("grow")
+load_file("grow_leaves")
+
+load_file("decompose")
+
 load_file("recipes")

mods/bg_tree/node.lua

@@ -29,30 +29,31 @@ blockgame.reg_simple_node("sapling", "Sapling", {
 	planty = 1,
 })
 
-blockgame.register_node(modname .. ":leaves", {
-	description = "Leaves",
-	drawtype = "glasslike",
-	tiles = {
-		modname .. "_leaves.png",
-	},
-	paramtype = "light",
-	sunlight_propagates = true,
-	groups = {
-		planty = 1,
-	},
+local function reg_leaves (name, desc, groups, drop)
+	blockgame.register_node(modname .. ":" .. name, {
+		description = desc,
+		drawtype = "glasslike",
+		tiles = {
+			modname .. "_" .. name .. ".png",
+		},
+		paramtype = "light",
+		sunlight_propagates = true,
+		groups = groups,
+		drop = drop,
+	})
+end
+
+reg_leaves("leaves", "Leaves", {
+	planty = 1,
+	air_flowable = 1,
 })
-blockgame.register_node(modname .. ":leaves_alive", {
-	description = "Growing Leaves",
-	drawtype = "glasslike",
-	tiles = {
-		modname .. "_leaves_alive.png",
-	},
-	paramtype = "light",
-	sunlight_propagates = true,
-	groups = {
-		planty = 1,
-	},
-	drop = modname .. ":leaves",
+reg_leaves("leaves_alive", "Growing Leaves", {
+	planty = 1,
+	air_flowable = 1,
+}, modname .. ":leaves")
+reg_leaves("leaves_decomposing", "Decomposing Leaves", {
+	planty = 1,
+	air_flowable = 1,
 })
 
 blockgame.reg_simple_node("nut", "Nut", {

mods/bg_tree/recipes.lua

@@ -4,12 +4,3 @@ local modname = minetest.get_current_modname()
 -- TODO: when recipes add support for groups, use `dirty` group here instead of specific nodes.
 blockgame.crafting.register_stack_recipe("bg_terrain:grass", modname .. ":nut", {name = modname .. ":sapling"})
 blockgame.crafting.register_stack_recipe("bg_terrain:dirt", modname .. ":nut", {name = modname .. ":sapling"})
-
-blockgame.crafting.register_pummel_recipe({
-	label = "pummel leaves into dirt",
-	used_item = modname .. ":leaves",
-	target_node = modname .. ":leaves",
-	on_success = function (pos, used_node, target_node)
-		minetest.set_node(pos, {name = "bg_terrain:dirt"})
-	end,
-})