Sponge cultivation overhaul.

- Inhibit sponge colony growth beyond a maximum size.  Players
  will have to prune colonies (or, smarter yet, split them) to
  grow more sponges.

- Allow sponge colony transplantation.  Sponges near the "core"
  of a colony (i.e. surrounded by more sponges) are more viable
  and more able to survive the player's crude harvesting.

docs/icebox.txt

@@ -12,6 +12,9 @@ ICEBOX: Low-Priority Ideas
 - Release an official beta pack/edition.
 	- Modpack of experimental features vs. alternate game by branch?
 
+- Flammable/igniter ABM should be reversed, so we scan over few igniters
+  instead of many flammables?
+
 - Wandering fluids API for concrete, glass?
 
 - AStMs: Active Stack Modifiers.

docs/issues.txt

@@ -13,16 +13,8 @@ ISSUES: Bugs, Cleanup and Refinements
   learned and things observed about where the game is headed.
 
 - Balance/nerf leaf composting rates.
-
-- Flammable/igniter ABM should be reversed, so we scan over few igniters
-  instead of many flammables?
-
-- Sponges grow way too much.
-	- Inhibit growth based on total in area.
-	- Allow transplantation of colonies.
-		- When digging, living sponge surrounded by at least
-		  8 other living sponges will dig as living instead
-		  of wet.
+	- Pack leaf nodes into a compost node?
+	- Need nearby moisture to compost?
 
 - Lode smelting changes.
 	- Currently lode smelting is too counterintuitive.

mods/nc_sponge/abm.lua

@@ -5,20 +5,6 @@ local minetest, nodecore, pairs
 
 local modname = minetest.get_current_modname()
 
-nodecore.register_limited_abm({
-		label = "Sponge Growth",
-		interval = 10,
-		chance = 1000,
-		limited_max = 100,
-		nodenames = {"group:water"},
-		neighbors = {modname .. ":sponge_living"},
-		action = function(pos)
-			if minetest.get_node({x = pos.x, y = pos.y - 1, z = pos.z}).name
-			~= "nc_terrain:sand" then return end
-			minetest.set_node(pos, {name = modname .. ":sponge_living"})
-		end
-	})
-
 nodecore.register_limited_abm({
 		label = "Sponge Wettening",
 		interval = 1,
@@ -44,7 +30,7 @@ nodecore.register_limited_abm({
 		interval = 1,
 		chance = 100,
 		limited_max = 100,
-		nodenames = {modname .. ":sponge_wet"},
+		nodenames = {modname .. ":sponge_wet", modname .. ":sponge_living"},
 		action = function(pos)
 			if minetest.get_node_light({x = pos.x, y = pos.y + 1, z = pos.z}) >= 15 then
 				minetest.sound_play("nc_api_craft_hiss", {gain = 0.02, pos = pos})
@@ -58,7 +44,7 @@ nodecore.register_limited_abm({
 		interval = 1,
 		chance = 20,
 		limited_max = 100,
-		nodenames = {modname .. ":sponge_wet"},
+		nodenames = {modname .. ":sponge_wet", modname .. ":sponge_living"},
 		neighbors = {"group:igniter"},
 		action = function(pos)
 			minetest.sound_play("nc_api_craft_hiss", {gain = 0.02, pos = pos})

mods/nc_sponge/cultivate.lua

@@ -0,0 +1,87 @@
+-- LUALOCALS < ---------------------------------------------------------
+local ItemStack, math, minetest, nodecore, pairs, vector
+    = ItemStack, math, minetest, nodecore, pairs, vector
+local math_pow, math_random
+    = math.pow, math.random
+-- LUALOCALS > ---------------------------------------------------------
+
+local modname = minetest.get_current_modname()
+
+local growdirs = nodecore.dirs()
+
+local living = modname .. ":sponge_living"
+
+nodecore.register_limited_abm({
+		label = "Sponge Growth",
+		interval = 10,
+		chance = 1000,
+		limited_max = 100,
+		nodenames = {living},
+		neighbors = {"group:water"},
+		action = function(pos)
+			local total = 0
+			if nodecore.scan_flood(pos, 6,
+				function(p, d)
+					if d >= 6 then return true end
+					if minetest.get_node(p).name ~= living then return false end
+					total = total + 1
+					if total >= 20 then return true end
+				end
+			) then return end
+
+			pos = vector.add(pos, growdirs[math_random(1, #growdirs)])
+
+			local node = minetest.get_node_or_nil(pos)
+			local def = node and minetest.registered_nodes[node.name]
+			local grp = def and def.groups and def.groups.water
+			if (not grp) or (grp < 1) then return end
+
+			local below = {x = pos.x, y = pos.y - 1, z = pos.z}
+			node = minetest.get_node(below)
+			if (math_random() > 0.1) or (node.name ~= living) then
+				def = minetest.registered_nodes[node.name]
+				grp = def and def.groups and def.groups.sand
+				if (not grp) or (grp < 1) then return end
+			end
+			minetest.set_node(pos, {name = living})
+		end
+	})
+
+-- A living sponge can be dug intact, RARELY, and ONLY if surrounded
+-- on all sides and edges (X/Z plane) by other living sponges.
+
+local digpos
+local old_node_dig = minetest.node_dig
+minetest.node_dig = function(pos, node, ...)
+	if (node and node.name) ~= living then
+		return old_node_dig(pos, node, ...)
+	end
+	local function helper(...)
+		digpos = nil
+		return ...
+	end
+	digpos = pos
+	return helper(old_node_dig(pos, node, ...))
+end
+local old_get_node_drops = minetest.get_node_drops
+minetest.get_node_drops = function(...)
+	local drops = old_get_node_drops(...)
+	if not digpos then return drops end
+	local neighbors = #minetest.find_nodes_in_area(
+		{x = digpos.x - 1, y = digpos.y - 1, z = digpos.z - 1},
+		{x = digpos.x + 1, y = digpos.y + 1, z = digpos.z + 1},
+		{living})
+	if neighbors >= 5 then
+		local prob = math_pow(2, neighbors - 5) * 0.005
+		if math_random() <= prob then return drops end
+	end
+	drops = drops or {}
+	for k, v in pairs(drops) do
+		v = ItemStack(v)
+		if v:get_name() == living then
+			v:set_name(modname .. ":sponge_wet")
+		end
+		drops[k] = v
+	end
+	return drops
+end

mods/nc_sponge/gen.lua

@@ -17,15 +17,6 @@ local c_sponge = minetest.get_content_id(modname .. ":sponge_living")
 nodecore.register_mapgen_shared(function(minp, maxp, area, data)
 		if minp.y > maxy or maxp.y < miny then return end
 
-		local function spawn(x, y, z)
-			nodecore.scan_flood({x = x, y = y, z = z}, 5, function(p)
-					if math_random() < 0.1 then return true end
-					local idx = area:index(p.x, p.y + 1, p.z)
-					if data[idx] ~= c_water then return false end
-					data[idx] = c_sponge
-				end)
-		end
-
 		local qty = math_floor(math_random() * (maxp.x - minp.x)
 			* (maxp.z - minp.z) / (64 * 64))
 		for _ = 1, qty do
@@ -42,7 +33,8 @@ nodecore.register_mapgen_shared(function(minp, maxp, area, data)
 				if cur == c_water then
 					waterabove = true
 				elseif cur == c_sand and waterabove then
-					spawn(x, y + 1, z)
+					local i = area:index(x, y + 1, z)
+					data[i] = c_sponge
 					break
 				else
 					break

mods/nc_sponge/init.lua

@@ -8,4 +8,5 @@ nodecore.amcoremod()
 include("node")
 include("abm")
 include("gen")
+include("cultivate")
 include("squeeze")

mods/nc_sponge/node.lua

@@ -46,6 +46,5 @@ minetest.register_node(modname .. ":sponge_living", {
 			moist = 1,
 			sponge = 1
 		},
-		drop = modname .. ":sponge_wet",
 		sounds = nodecore.sounds("nc_terrain_swishy")
 	})