Add .is_sapling() and new forest command.

It's not hooked up yet and we haven't implemented the chat command, so 
it's obviously untested.

worldeditadditions/lib/forest.lua

@@ -0,0 +1,82 @@
+--- Overlap command. Places a specified node on top of each column.
+-- @module worldeditadditions.layers
+
+
+function worldeditadditions.forest(pos1, pos2, sapling_weights)
+	pos1, pos2 = worldedit.sort_pos(pos1, pos2)
+	
+	-- This command requires the bonemeal mod to be installed
+	-- We check here too because other mods might call this function directly and bypass the chat command system
+	if not minetest.get_modpath("bonemeal") then
+		return false, "Bonemeal mod not loaded"
+	end
+	
+	worldeditadditions.overlay(pos1, pos2, sapling_weights)
+	
+	-- Fetch the nodes in the specified area
+	local manip, area = worldedit.manip_helpers.init(pos1, pos2)
+	local data = manip:get_data()
+	local id_air = minetest.get_content_id("air")
+	
+	local group_cache = {}
+	local stats = { attempts = {}, failures = 0 }
+	for z = pos2.z, pos1.z, -1 do
+		for x = pos2.x, pos1.x, -1 do
+			for y = pos2.y, pos1.y, -1 do
+				local i = area:index(x, y, z)
+				if not groups_cache[data[i]] then
+					group_cache[data[i]] = worldeditadditions.is_sapling(data[i])
+				end
+				
+				if group_cache[data[i]] then
+					local did_grow = false
+					for i=1,100 do
+						bonemeal:on_use(
+							{ x = x, y = y, z = z },
+							4,
+							nil
+						)
+						
+						local new_id_at_pos = minetest.get_content_id(minetest.get_node({ z = z, y = y, x = x }).name)
+						if not groups_cache[new_id_at_pos] then
+							group_cache[new_id_at_pos] = worldeditadditions.is_sapling(new_id_at_pos)
+						end
+						if not group_cache[new_id_at_pos] then
+							did_grow = true
+							table.insert(stats.attempts, i)
+							break
+						end
+					end
+					if not did_grow then
+						-- We can't set it to air here because then when we save back we would overwrite all the newly grown trees
+						stats.failures = stats.failures + 1
+					end
+				end
+			end
+		end
+	end
+	
+	-- Re-fetch the Voxel Manipulator to accountn for the new trees
+	manip, area = worldedit.manip_helpers.init(pos1, pos2)
+	data = manip:get_data()
+	
+	for z = pos2.z, pos1.z, -1 do
+		for x = pos2.x, pos1.x, -1 do
+			for y = pos2.y, pos1.y, -1 do
+				local i = area:index(x, y, z)
+				if not groups_cache[data[i]] then
+					group_cache[data[i]] = worldeditadditions.is_sapling(data[i])
+				end
+				
+				if group_cache[data[i]] then
+					data[i] = air
+				end
+			end
+		end
+	end
+	
+	
+	-- Save the modified nodes back to disk & return
+	worldedit.manip_helpers.finish(manip, data)
+	return true, stats
+end

worldeditadditions/lib/layers.lua

@@ -1,5 +1,5 @@
 --- Overlap command. Places a specified node on top of each column.
--- @module worldeditadditions.overlay
+-- @module worldeditadditions.layers
 
 function worldeditadditions.layers(pos1, pos2, node_weights)
 	pos1, pos2 = worldedit.sort_pos(pos1, pos2)

worldeditadditions/utils/nodes.lua

@@ -32,6 +32,7 @@ local node_id_air = minetest.get_content_id("air")
 local node_id_ignore = minetest.get_content_id("ignore")
 
 --- Determines whether the given node/content id is an airlike node or not.
+-- It is recommended that the result of this function be cached.
 -- @param	id		number	The content/node id to check.
 -- @return	bool	Whether the given node/content id is an airlike node or not.
 function worldeditadditions.is_airlike(id)
@@ -62,6 +63,7 @@ function worldeditadditions.is_airlike(id)
 end
 
 --- Determines whether the given node/content id is a liquid-ish node or not.
+-- It is recommended that the result of this function be cached.
 -- @param	id		number	The content/node id to check.
 -- @return	bool	Whether the given node/content id is a liquid-ish node or not.
 function worldeditadditions.is_liquidlike(id)
@@ -78,3 +80,13 @@ function worldeditadditions.is_liquidlike(id)
 	-- If it's not none, then it has to be a liquid as the only other values are source and flowing
 	return true
 end
+
+--- Determines whether the given node/content id is a sapling or not.
+-- Nodes with the "sapling" group are considered saplings.
+-- It is recommended that the result of this function be cached.
+-- @param	id		number	The content/node id to check.
+-- @return	bool	Whther the given node/content id is a sapxling or not.
+function worldeditadditions.is_sapling(id)
+	local node_name = minetest.get_name_from_content_id(data[i])
+	return minetest.get_item_group(node_name, "sapling") ~= 0
+end