elepower/elepower_farming/treecutter.lua

-- Remove entire trees
-- This code is taken from TreeCapitator by HybridDog (WTFPL)
-- https://github.com/HybridDog/treecapitator


-- see elepower_papi >> external_nodes_items.lua for explanation
-- shorten table ref
local epi = ele.external.ing

local load_time_start = minetest.get_us_time()

------------------------------------- Settings ---------------------------------

-- default settings
elefarm.tc = {
	stem_height_min = 3,
	default_tree = {
		trees = {epi.tree},
		leaves = {epi.leaves},
		range = 2,
		fruits = {},
		type = "default",
	},
	after_register = {},
}

-------------------------- Common functions ------------------------------------

local poshash = minetest.hash_node_position

local function hash2(x, y)
	return y * 0x10000 + x
end

-- don't use minetest.get_node more times for the same position (caching)
local known_nodes
local function clean_cache()
	known_nodes = {}
	setmetatable(known_nodes, {__mode = "kv"})
end
clean_cache()

local function remove_node(pos)
	known_nodes[poshash(pos)] = {name="air", param2=0}
	minetest.remove_node(pos)
	minetest.check_for_falling(pos)
end

local function get_node(pos)
	local vi = poshash(pos)
	local node = known_nodes[vi]
	if node then
		return node
	end
	node = minetest.get_node(pos)
	known_nodes[vi] = node
	return node
end

--definitions of functions for the destruction of nodes
local creative = minetest.settings:get_bool"creative_mode"

destroy_node = function(pos, node, digger, drops)
	known_nodes[poshash(pos)] = {name="air", param2=0}

	if not digger and drops then
		drops[#drops + 1] = node.name
		minetest.set_node(pos, {name="air", param2=0})
		return
	end

	minetest.node_dig(pos, node, digger)
end

function remove_leaf(pos, node, drops)
	local leaves_drops = minetest.get_node_drops(node.name)
	for _, itemname in pairs(leaves_drops) do
		if itemname ~= node.name then
			drops[#drops + 1] = itemname
		end
	end
	remove_node(pos)
end

table_contains = function(t, v)
	for i = 1,#t do
		if t[i] == v then
			return true
		end
	end
	return false
end

-- the functions for the available types
local capitate_funcs = {}

------------------------ Function for regular trees ----------------------------

-- tests if the node is a trunk which could belong to the same tree sort
local function is_trunk_of_tree(trees, node)
	-- param2 is not longer tested to be 0 but smaller than 4
	-- because sometimes the trunk is a bit rotated
	return node.param2 < 4
		and trees ^ node.name
end

-- test if the trunk node there is the top trunk node of a neighbour tree
-- if so, constrain the possible leaves positions
local function get_a_tree(pos, tab, tr, xo,yo,zo)
	local p = {x=pos.x + xo, y=pos.y + yo, z=pos.z + zo}

	-- tests if a trunk is at the current pos
	local nd = get_node(p)
	if not is_trunk_of_tree(tr.trees, nd) then
		return false
	end

	-- search for a leaves or fruit node next to the trunk
	local leaf = get_node{x=p.x, y=p.y+1, z=p.z}.name
	if not tr.leaves ^ leaf
	and not tr.fruits ^ leaf then
		local leaf = get_node{x=p.x, y=p.y, z=p.z+1}.name
		if not tr.leaves ^ leaf
		and not tr.fruits ^ leaf then
			return false
		end
	end

	-- search for the requisite amount of stem trunk nodes
	for _ = 1, tr.stem_height_min-1 do
		p.y = p.y-1
		if not is_trunk_of_tree(tr.trees, get_node(p)) then
			return false
		end
	end
	p.y = p.y + tr.stem_height_min-1

	local r = tr.range
	local r_up = tr.range_up or r
	local r_down = tr.range_down or r

	-- reduce x and z avoidance range for thick stem neighbour trees
	if tr.stem_type == "2x2" then
		r = r - 1
	elseif tr.stem_type == "+" then
		r = r - 2
	end

	-- tag places which should not be removed
	local z1 = math.max(-r + zo, -r)
	local z2 = math.min(r + zo, r)
	local y1 = math.max(-r_down + yo, -r_down)
	local y2 = math.min(r_up + yo, r_up)
	local x1 = math.max(-r + xo, -r)
	local x2 = math.min(r + xo, r)
	for z = z1,z2 do
		for y = y1,y2 do
			local i = poshash{x=x1, y=y, z=z}
			for _ = x1,x2 do
				tab[i] = true
				i = i+1
			end
		end
	end
	return true
end

-- returns positions for leaves allowed to be dug
local function find_valid_head_ps(pos, head_ps, trunktop_ps, tr)
	-- exclude the stem nodes
	local before_stems = {}
	for i = 1,#trunktop_ps do
		local p = vector.subtract(trunktop_ps[i], pos)
		before_stems[hash2(p.x, p.z)] = p.y+1
	end

	local r = tr.range
	local r_up = tr.range_up or r
	local r_down = tr.range_down or r

	-- firstly, detect neighbour trees of the same sort to not hurt them
	local tab = {}
	local rx2 = 2 * r
	local rupdown = r_up + r_down
	for z = -rx2, rx2 do
		for x = -rx2, rx2 do
			local bot = before_stems[hash2(x, z)] or -rupdown
			for y = rupdown, bot, -1 do
				if get_a_tree(pos, tab, tr, x,y,z) then
					break
				end
			end
		end
	end
	-- now, get the head positions without the neighbouring trees
	local n = #head_ps
	for z = -r,r do
		for x = -r,r do
			local bot = before_stems[hash2(x, z)] or -r_down
			for y = bot,r_up do
				local p = {x=x, y=y, z=z}
				if not tab[poshash(p)] then
					n = n+1
					head_ps[n] = vector.add(pos, p)
				end
			end
		end
	end
	return n
end

-- adds the stem to the trunks
local function get_stem(trunktop_ps, trunks, tr, head_ps)
	if tr.cutting_leaves then
		elefarm.tc.moretrees34(trunktop_ps, trunks, tr, head_ps,
			get_node, is_trunk_of_tree)
		return
	end
	for i = 1,#trunktop_ps do
		local pos = trunktop_ps[i]
		local node = get_node(pos)
		while is_trunk_of_tree(tr.trees, node) do
			trunks[#trunks+1] = {pos, node}
			pos = {x=pos.x, y=pos.y+1, z=pos.z}
			node = get_node(pos)
		end

		-- renew trunk top position
		pos.y = pos.y-1
		trunktop_ps[i] = pos
	end
end

-- part of healthy stem searching
local function here_neat_stemps(p, tr)
	local ps = {}
	for i = 1,#tr.stem_offsets do
		local o = tr.stem_offsets[i]
		local p = {x = p.x + o[1], y = p.y, z = p.z + o[2]}
		-- air test is too simple (makeshift solution)
		if get_node(p).name ~= "air" then
			return
		end
		p.y = p.y+1
		if not is_trunk_of_tree(tr.trees, get_node(p)) then
			return
		end
		ps[#ps+1] = p
	end
	return ps
end

-- gives stem positions of a healthy tree
local function find_neat_stemps(pos, tr)
	for i = 1,#tr.stem_offsets do
		local o = tr.stem_offsets[i]
		local p = {x = pos.x - o[1], y = pos.y, z = pos.z - o[2]}
		local ps = here_neat_stemps(p, tr)
		if ps then
			return ps
		end
	end
	-- nothing found
end

-- part of incomplete stem searching
local function here_incomplete_stemps(p, tr)
	local ps = {}
	for i = 1,#tr.stem_offsets do
		local o = tr.stem_offsets[i]
		local p = {x = p.x + o[1], y = p.y+1, z = p.z + o[2]}
		if is_trunk_of_tree(tr.trees, get_node(p)) then
			p.y = p.y-1
			local node = get_node(p)
			if is_trunk_of_tree(tr.trees, node) then
				-- stem wasn't chopped enough
				return {}
			end
			-- air test is too simple (makeshift solution)
			if node.name == "air" then
				p.y = p.y+1
				ps[#ps+1] = p
			end
		end
	end
	-- #ps ∈ [3]
	return ps
end

-- gives stem positions of an eroded tree
local function find_incomplete_stemps(pos, tr)
	local ps
	local stemcount = 0
	for i = 1,#tr.stem_offsets do
		local o = tr.stem_offsets[i]
		local p = {x = pos.x - o[1], y = pos.y, z = pos.z - o[2]}
		local cps = here_incomplete_stemps(p, tr)
		local cnt = #cps
		if cnt == 0 then
			-- player needs to chop more
			return
		end
		if stemcount < cnt then
			stemcount = #cps
			ps = cps
		end
	end
	return ps
end

-- returns the lowest trunk node positions
local function get_stem_ps(pos, tr)
	if not tr.stem_type then
		-- 1x1 stem
		return {{x=pos.x, y=pos.y+1, z=pos.z}}
	end
	return find_neat_stemps(pos, tr)
		or find_incomplete_stemps(pos, tr)
end

-- gets the middle position of the tree head
local function get_head_center(trunktop_ps, stem_type)
	if stem_type == "2x2" then
		-- return the highest position
		local pos = trunktop_ps[1]
		for i = 2,#trunktop_ps do
			local p = trunktop_ps[i]
			if p.y > pos.y then
				pos = p
			end
		end
		return pos
	elseif stem_type == "+" then
		-- return the middle position
		local mid = vector.new()
		for i = 1,#trunktop_ps do
			mid = vector.add(mid, trunktop_ps[i])
		end
		return vector.round(vector.divide(mid, #trunktop_ps))
	else
		return trunktop_ps[1]
	end
end

function capitate_funcs.default(pos, tr, _, digger)
	local drops = {}
	local trees = tr.trees

	-- get the stem trunks
	local trunks = {}
	local trunktop_ps = get_stem_ps(pos, tr)
	if not trunktop_ps then
		return
	end
	local head_ps = {}
	get_stem(trunktop_ps, trunks, tr, head_ps)

	local leaves = tr.leaves
	local fruits = tr.fruits
	local hcp = get_head_center(trunktop_ps, tr.stem_type)

	-- abort if the tree lacks leaves/fruits
	local ln = get_node{x=hcp.x, y=hcp.y+1, z=hcp.z}
	if not leaves ^ ln.name
	and not fruits ^ ln.name then
		local leaf = get_node{x=hcp.x, y=hcp.y, z=hcp.z+1}.name
		if not leaves ^ leaf
		and not fruits ^ leaf then
			return
		end
	end

	-- get leaves, fruits and stem fruits
	local leaves_found = {}
	local n = find_valid_head_ps(hcp, head_ps, trunktop_ps, tr)
	local leaves_toremove = {}
	local fruits_toremove = {}
	for i = 1,n do
		local p = head_ps[i]
		local node = get_node(p)
		local nodename = node.name
		if not is_trunk_of_tree(trees, node) then
			if leaves ^ nodename then
				leaves_found[nodename] = true
				leaves_toremove[#leaves_toremove+1] = {p, node}
			elseif fruits ^ nodename then
				fruits_toremove[#fruits_toremove+1] = {p, node}
			end
		elseif tr.trunk_fruit_vertical
		and fruits ^ nodename then
			trunks[#trunks+1] = {p, node}
		end
	end

	if tr.requisite_leaves then
		-- abort if specific leaves weren't found
		for i = 1,#tr.requisite_leaves do
			if not leaves_found[tr.requisite_leaves[i]] then
				return nil
			end
		end
	end

	-- remove fruits at first due to attachment
	-- and disable nodeupdate temporarily
	local nodeupdate = minetest.check_for_falling
	minetest.check_for_falling = function() end
	for i = 1,#fruits_toremove do
		destroy_node(fruits_toremove[i][1], fruits_toremove[i][2], digger, drops)
	end
	minetest.check_for_falling = nodeupdate
	for i = 1,#leaves_toremove do
		remove_leaf(leaves_toremove[i][1], leaves_toremove[i][2], drops, digger)
	end
	for i = 1,#trunks do
		destroy_node(trunks[i][1], trunks[i][2], digger, drops)
	end

	return drops
end

-- metatable for shorter code: trees ^ name ≙ name ∈ trees
local mt_default = {
	__pow = table_contains
}
elefarm.tc.after_register.default = function(tr)
	setmetatable(tr.trees, mt_default)
	setmetatable(tr.leaves, mt_default)
	setmetatable(tr.fruits, mt_default)
	tr.range_up = tr.range_up or tr.range
	tr.range_down = tr.range_down or tr.range
	tr.stem_height_min = tr.stem_height_min or elefarm.tc.stem_height_min

	if tr.stem_type == "2x2" then
		tr.stem_offsets = {
			{0,0}, {1,0},
			{0,1}, {1,1},
		}
	elseif tr.stem_type == "+" then
		tr.stem_offsets = {
			{0,0},
				{0,1},
			{-1,0},	{1,0},
				{0,-1},
		}
	end
end

--------------------- Acacia tree function -------------------------------------

function capitate_funcs.acacia(pos, tr, node_above, digger)
	local drops = {}
	local trunk = tr.trees[1]

	-- fill tab with the stem trunks
	local tab, n = {{{x=pos.x, y=pos.y+1, z=pos.z}, node_above}}, 2
	local np = {x=pos.x, y=pos.y+2, z=pos.z}
	local nd = get_node(np)
	while trunk == nd.name
	and nd.param2 < 4 do
		tab[n] = {vector.new(np), nd}
		n = n+1
		np.y = np.y+1
		nd = get_node(np)
	end
	np.y = np.y-1

	for z = -1,1,2 do
		for x = -1,1,2 do
			-- add the other trunks to tab
			local p = vector.new(np)
			p.x = p.x+x
			p.z = p.z+z
			local nd = get_node(p)
			if nd.name ~= trunk then
				p.y = p.y+1
				nd = get_node(p)
				if nd.name ~= trunk then
					return
				end
			end
			tab[n] = {vector.new(p), nd}

			p.x = p.x+x
			p.z = p.z+z
			p.y = p.y+1

			if get_node(p).name ~= trunk then
				return
			end
			tab[n+1] = {vector.new(p), nd}
			n = n+2

			-- get neighbouring acacia trunks for delimiting
			local no_rms = {}
			for z = -4,4 do
				for x = -4,4 do
					if math.abs(x+z) ~= 8
					and (x ~= 0 or z ~= 0) then
						if get_node{x=p.x+x, y=p.y, z=p.z+z}.name == trunk
						and get_node{x=p.x+x, y=p.y+1, z=p.z+z}.name == tr.leaf then
							for z = math.max(-4, z-2), math.min(4, z+2) do
								for x = math.max(-4, x-2), math.min(4, x+2) do
									no_rms[(z+4)*9 + x+4] = true
								end
							end
						end
					end
				end
			end

			-- remove leaves
			p.y = p.y+1
			local i = 0
			for z = -4,4 do
				for x = -4,4 do
					if not no_rms[i] then
						local p = {x=p.x+x, y=p.y, z=p.z+z}
						local node = get_node(p)
						if node.name == tr.leaf then
							remove_leaf(p, node, drops, digger)
						end
					end
					i = i+1
				end
			end
		end
	end

	-- dig the stem
	for i = 1,n-1 do
		local pos,node = unpack(tab[i])
		destroy_node(pos, node, digger, drops)
	end

	return drops
end

----------------------- Palm tree function -------------------------------------

-- the 17 vectors used for walking the stem
local palm_stem_dirs = {
	{0,1,0}
}
local n = 2
for i = -1,1,2 do
	palm_stem_dirs[n] = {i,0,0}
	palm_stem_dirs[n+1] = {0,0,i}
	n = n+2
end
for i = -1,1,2 do
	palm_stem_dirs[n] = {i,0,i}
	palm_stem_dirs[n+1] = {i,0,-i}
	n = n+2
end
for i = -1,1,2 do
	palm_stem_dirs[n] = {i,1,0}
	palm_stem_dirs[n+1] = {0,1,i}
	n = n+2
end
for i = -1,1,2 do
	palm_stem_dirs[n] = {i,1,i}
	palm_stem_dirs[n+1] = {i,1,-i}
	n = n+2
end
for i = 1,17 do
	local p = palm_stem_dirs[i]
	palm_stem_dirs[i] = vector.new(unpack(p))
end

local pos_from_hash = minetest.get_position_from_hash

-- gets a list of leaves positions
local function get_palm_head(hcp, tr, max_forbi)
	local pos = {x=hcp.x, y=hcp.y+1, z=hcp.z}
	local leaves = {}
	if get_node(pos).name ~= tr.leaves then
		-- search hub position
		for xo = -1,1 do
			for zo = -1,1 do
				local p = {x=pos.x+xo, y=pos.y, z=pos.z+zo}
				if get_node(p).name == tr.leaves then
					pos = p
				end
			end
		end
	end
	-- collect leaves
	leaves[poshash(pos)] = true
	for i = -1,1 do
		for j = -1,1 do
			-- don't search around the corner except max_forbi time(s)
			local dirs = {{0,0}, {i,0}, {0,j}, {i,j},  {-i,0}, {0,-j}}
			local avoids = {}
			local todo = {pos}
			local sp = 1
			while sp > 0 do
				local p = todo[sp]
				sp = sp-1
				-- only walk the "forbidden" dir if still allowed
				local forbic = avoids[poshash(p)] or 0
				local dirc = 6
				if forbic == max_forbi then
					dirc = dirc - 2
				end
				-- walk the directions
				for i = 1,dirc do
					-- increase forbidden when needed
					local forbinc = forbic
					if i > 4 then
						forbinc = forbinc+1
					end
					local xz = dirs[i]
					for y = -1,2 do
						local p = {x=p.x+xz[1], y=p.y+y, z=p.z+xz[2]}
						local ph = poshash(p)
						local forbi = avoids[ph]
						if not forbi
						or forbi > forbinc then
							avoids[ph] = forbinc
							local dif = vector.subtract(p, pos)
							if get_node(p).name == tr.leaves
							and math.abs(dif.x) <= tr.range
							and math.abs(dif.z) <= tr.range
							and dif.y <= tr.range_up
							and dif.y >= -tr.range_down then
								sp = sp+1
								todo[sp] = p
								leaves[ph] = true
							end
						end
					end
				end
			end
		end
	end
	local ps = {}
	local n = 0
	for ph in pairs(leaves) do
		n = n+1
		ps[n] = pos_from_hash(ph)
	end
	return ps,n
end

-- returns positions for palm leaves allowed to be dug
local function palm_find_valid_head_ps(pos, head_ps, tr)
	local r = tr.range
	local r_up = tr.range_up or r
	local r_down = tr.range_down or r

	-- firstly, detect neighbour palms' leaves to not hurt them
	local tab = {}
	local rx2 = 2 * r
	local rupdown = r_up + r_down
	for z = -rx2, rx2 do
		for y = -rupdown, rupdown do
			for x = -rx2, rx2 do
				local hcp = {x=pos.x+x, y=pos.y+y, z=pos.z+z}
				if not vector.equals(hcp, pos)
				and get_node(hcp).name == tr.trunk_top then
					local leaves,n = get_palm_head(hcp, tr, 0)
					for i = 1,n do
						tab[poshash(leaves[i])] = true
					end
				end
			end
		end
	end
	-- now, get the leaves positions without the neighbouring leaves
	local leaves,lc = get_palm_head(pos, tr, tr.max_forbi)
	local n = #head_ps
	for i = 1,lc do
		local p = leaves[i]
		if not tab[poshash(p)] then
			n = n+1
			head_ps[n] = p
		end
	end
	return n
end

function capitate_funcs.palm(pos, tr, node_above, digger)
	local drops = {}
	local trunk = tr.trees[1]

	-- walk the stem up to the fruit carrier
	pos = {x=pos.x, y=pos.y+1, z=pos.z}
	local trunks = {{pos, node_above}}
	local trunk_found = true
	local nohori = false
	local hcp
	while trunk_found
	and not hcp do
		trunk_found = false
		for i = 1,17 do
			local hori = i > 1 and i < 10
			if not hori
			or not nohori then
				local p = vector.add(pos, palm_stem_dirs[i])
				local node = get_node(p)
				if node.name == trunk then
					trunk_found = true
					trunks[#trunks+1] = {p, node}
					pos = p
					nohori = hori
					break
				end
				if node.name == tr.trunk_top then
					hcp = p
					trunks[#trunks+1] = {p, node}
					break
				end
			end
		end
	end
	if not hcp then
		return nil
	end

	-- collect coconuts
	local fruits = {}
	for zo = -1,1 do
		for xo = -1,1 do
			local p = {x=hcp.x+xo, y=hcp.y, z=hcp.z+zo}
			local node = get_node(p)
			if node.name:sub(1, #tr.fruit) == tr.fruit then
				fruits[#fruits+1] = {p, node}
			end
		end
	end

	-- find the leaves of the palm
	local leaves_ps = {}
	local lc = palm_find_valid_head_ps(hcp, leaves_ps, tr)

	local nodeupdate = minetest.check_for_falling
	minetest.check_for_falling = function() end
	for i = 1,#fruits do
		local pos,node = unpack(fruits[i])
		destroy_node(pos, node, digger, drops)
	end
	minetest.check_for_falling = nodeupdate

	for i = 1,#trunks do
		local pos,node = unpack(trunks[i])
		destroy_node(pos, node, digger, drops)
	end

	for i = 1,lc do
		local pos = leaves_ps[i]
		remove_leaf(pos, get_node(pos), drops, digger)
	end
	return drops
end


---------------------- A moretrees capitation function -------------------------

-- table iteration instead of recursion
local function get_tab(pos, func, max)
	local todo = {pos}
	local n = 1
	local tab_avoid = {[poshash(pos)] = true}
	local tab_done,num = {pos},2
	while n ~= 0 do
		local p = todo[n]
		n = n-1
		--[[
		for i = -1,1,2 do
			for _,p2 in pairs{
				{x=p.x+i, y=p.y, z=p.z},
				{x=p.x, y=p.y+i, z=p.z},
				{x=p.x, y=p.y, z=p.z+i},
			} do]]
		for i = -1,1 do
			for j = -1,1 do
				for k = -1,1 do
					local p2 = {x=p.x+i, y=p.y+j, z=p.z+k}
					local vi = poshash(p2)
					if not tab_avoid[vi]
					and func(p2) then
						n = n+1
						todo[n] = p2

						tab_avoid[vi] = true

						tab_done[num] = p2
						num = num+1

						if max
						and num > max then
							return false
						end
					end
				end
			end
		end
	end
	return tab_done
end

function capitate_funcs.moretrees(pos, tr, _, digger)
	local drops = {}
	local trees = tr.trees
	local leaves = tr.leaves
	local fruits = tr.fruits
	local minx = pos.x-tr.range
	local maxx = pos.x+tr.range
	local minz = pos.z-tr.range
	local maxz = pos.z+tr.range
	local maxy = pos.y+tr.height
	local num_trunks = 0
	local num_leaves = 0
	local ps = get_tab({x=pos.x, y=pos.y+1, z=pos.z}, function(pos)
		if pos.x < minx
		or pos.x > maxx
		or pos.z < minz
		or pos.z > maxz
		or pos.y > maxy then
			return nil
		end
		local nam = get_node(pos).name
		if table_contains(trees, nam) then
			num_trunks = num_trunks+1
		elseif table_contains(leaves, nam) then
			num_leaves = num_leaves+1
		elseif not table_contains(fruits, nam) then
			return nil
		end
		return drops
	end, tr.max_nodes)
	if not ps then
		print"no ps found"
		return
	end
	if num_trunks < tr.num_trunks_min
	or num_trunks > tr.num_trunks_max then
		print("wrong trunks num: "..num_trunks)
		return
	end
	if num_leaves < tr.num_leaves_min
	or num_leaves > tr.num_leaves_max then
		print("wrong leaves num: "..num_leaves)
		return
	end
	for _,p in pairs(ps) do
		local node = get_node(p)
		local nodename = node.name
		if table_contains(leaves, nodename) then
			remove_leaf(p, node, drops, digger)
		else
			destroy_node(p, node, digger, drops)
		end
	end
	return drops
end

function elefarm.tc.moretrees34(trunktop_ps, trunks, tr, head_ps, get_node, is_trunk_of_tree)
	local trees = tr.trees
	for i = 1,#trunktop_ps do
		-- add the usual trunks
		local pos = trunktop_ps[i]
		local node = get_node(pos)
		while is_trunk_of_tree(trees, node) do
			trunks[#trunks+1] = {pos, node}
			pos = {x=pos.x, y=pos.y+1, z=pos.z}
			node = get_node(pos)
		end

		-- meddle with the lacunarity
		local ys = pos.y
		local ye
		local detected_trunks = {}

		-- search upwards until the gap is big enough or the tree ended
		local foundleaves = 0
		while true do
			if is_trunk_of_tree(trees, node) then
				foundleaves = 0
				detected_trunks[pos.y] = node
				pos.y = pos.y+1
				node = get_node(pos)
			elseif tr.leaves ^ node.name
			or tr.fruits ^ node.name then
				foundleaves = foundleaves+1
				if foundleaves > tr.cutting_leaves then
					-- cutting leaves count exceeded
					ye = pos.y-foundleaves
					break
				end
				pos.y = pos.y+1
				node = get_node(pos)
			else
				-- above the tree
				ye = pos.y-1
				break
			end
		end

		-- search downwards until enough trunks are found above each other
		-- or no such trunks are found
		local ytop = ys-1
		local y = ye
		local last_test = ys + tr.stem_height_min
		while y >= last_test do
			if detected_trunks[y] then
				local too_short
				for ty = y - tr.stem_height_min + 1, y-1 do
					if not detected_trunks[y] then
						too_short = true
						y = ty-1
						break
					end
				end
				if not too_short then
					-- upper end found
					ytop = y
					break
				end
			end
			y = y-1
		end

		if ytop >= ys then
			-- add trunks and leaves/fruits
			for y = ys, ytop do
				local p = {x=pos.x, y=y, z=pos.z}
				if detected_trunks[y] then
					trunks[#trunks+1] = {p, detected_trunks[y]}
				else
					head_ps[#head_ps+1] = p
				end
			end
		end

		-- renew trunk top position
		pos.y = ytop
		trunktop_ps[i] = pos
	end
end

--------------------------- api interface --------------------------------------

-- the function which is used for capitating
local capitating = false
function elefarm.tc.capitate_tree(pos, player)
	if capitating then
		return
	end
	capitating = true

	local t1 = minetest.get_us_time()
	local node_above = get_node{x=pos.x, y=pos.y+1, z=pos.z}
	local capitated = nil
	for i = 1,#elefarm.tc.trees do
		local tr = elefarm.tc.trees[i]
		if table_contains(tr.trees, node_above.name) and node_above.param2 < 4 then
			local pd = capitate_funcs[tr.type](pos, tr, node_above, player)
			if pd and #pd > 0 then
				capitated = pd
				break
			end
		end
	end

	capitating = false
	if capitated then
		clean_cache()
		minetest.log("info", "[elefarming tc] tree capitated at (" ..
			pos.x .. "|" .. pos.y .. "|" .. pos.z .. ") after ca. " ..
			(minetest.get_us_time() - t1) / 1000000 .. " s")
	end

	return capitated
end

---------
-- API --
---------

-- the table containing the tree definitions
elefarm.tc.trees = {}

local after_dig_wrap
local after_dig_nodes = {}

function elefarm.tc.register_tree(tr)
	for name,value in pairs(elefarm.tc.default_tree) do
		if tr[name] == nil then
			tr[name] = value	--replaces not defined stuff
		end
	end
	elefarm.tc.trees[#elefarm.tc.trees+1] = tr
	if elefarm.tc.after_register[tr.type] then
		elefarm.tc.after_register[tr.type](tr)
	end
end

-- Mods can set elefarm.tc.capitation_usually_disallowed to true and
-- override this function, with params pos and digger, to make capitation
-- transpire only under certain contitions.
function elefarm.tc.capitation_allowed()
	return not elefarm.tc.capitation_usually_disallowed
end

-- test if trunk nodes were redefined
minetest.after(2, function()
	for nodename in pairs(after_dig_nodes) do
		if not minetest.registered_nodes[nodename].after_dig_node then
			error(nodename .. " didn't keep after_dig_node.")
		end
	end
	after_dig_nodes = nil
end)

-- wrapping is necessary, someone may overwrite elefarm.tc.capitate_tree
function after_dig_wrap(pos, _,_, digger)
	elefarm.tc.capitate_tree(pos, digger)
end

------------------
-- Registration --
------------------

-- Please try to match the tree definition close to the real tree for a more
-- fitting usage of neighbour detection and similar mechanisms.
local mgname = minetest.get_mapgen_setting"mg_name"

if mgname == "v6" then
	elefarm.tc.register_tree{
		trees = {epi.tree},
		leaves = {epi.leaves},
		range = 2,
		fruits = {epi.apple}
	}

	elefarm.tc.register_tree({
		trees = {epi.jungle_tree},
		leaves = {epi.jungle_leaves},
		range = 3
	})
else
	elefarm.tc.register_tree{
		trees = {epi.tree},
		leaves = {epi.leaves},
		range = 2,
		range_up = 4,
		range_down = 0,
		fruits = {epi.apple, epi.tree},
		trunk_fruit_vertical = true
	}

	elefarm.tc.register_tree({
		trees = {epi.jungle_tree},
		leaves = {epi.jungle_leaves},
		fruits = {epi.jungle_tree},
		range = 4,
		range_up = 14,
		range_down = 5,
		trunk_fruit_vertical = true,
		stem_height_min = 12,
	})

	elefarm.tc.register_tree({
		trees = {epi.jungle_tree},
		leaves = {epi.jungle_leaves},
		fruits = {epi.jungle_tree},
		range = 4,
		range_up = 14,
		range_down = 3,
		trunk_fruit_vertical = true,
		stem_type = "2x2",
		stem_height_min = 12,
	})
end

elefarm.tc.register_tree({
	trees = {epi.pine_tree},
	leaves = {epi.pine_needles},
	-- the +2 height is used to also support the coned pine trees
	range_up = 2 +2,
	range_down = 6,
	range = 3,
})

elefarm.tc.register_tree({
	trees = {epi.acacia_tree},
	leaf = epi.acacia_leaves,
	no_param2test = true,
	--leavesrange = 4,
	type = "acacia"
})

elefarm.tc.register_tree({
	trees = {epi.aspen_tree},
	leaves = {epi.aspen_leaves},
	range = 4,
})

if minetest.get_modpath("farming_plus") then
	elefarm.tc.register_tree({
		trees = {epi.tree},
		leaves = {"farming_plus:banana_leaves"},
		range = 2,
		fruits = {"farming_plus:banana"}
	})

	elefarm.tc.register_tree({
		trees = {epi.tree},
		leaves = {"farming_plus:cocoa_leaves"},
		range = 2,
		fruits = {"farming_plus:cocoa"}
	})
end

if minetest.get_modpath("moretrees") then
	elefarm.tc.register_tree({
		trees = {"moretrees:acacia_trunk"},
		leaves = {"moretrees:acacia_leaves"},
		range = 10,
	})

	elefarm.tc.register_tree{
		trees = {"moretrees:poplar_trunk"},
		leaves = {"moretrees:poplar_leaves"},
		range_up = 5,
		range_down = 17,
		range = 2,
	}

	local dates = {"moretrees:dates_fn", "moretrees:dates_m0",
		"moretrees:dates_n"}
	for i = 0, 4 do
		dates[#dates+1] = "moretrees:dates_f" .. i
	end
	dates[#dates+1] = "moretrees:date_palm_trunk"
	elefarm.tc.register_tree{
		trees = {
			"moretrees:date_palm_trunk",
			"moretrees:date_palm_mfruit_trunk",
			"moretrees:date_palm_ffruit_trunk"
		},
		leaves = {"moretrees:date_palm_leaves"},
		fruits = dates,
		trunk_fruit_vertical = true,
		range = 11,
		range_up = 15,
		range_down = 0,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:apple_tree_trunk"},
		leaves = {"moretrees:apple_tree_leaves"},
		fruits = {epi.apple, "moretrees:apple_tree_trunk"},
		trunk_fruit_vertical = true,
		range = 9,
		range_up = 3,
		range_down = 4,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:beech_trunk"},
		leaves = {"moretrees:beech_leaves"},
		range = 4,
		range_down = 2,
		range_up = 3,
		fruits = {"moretrees:beech_trunk"},
		trunk_fruit_vertical = true
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:birch_trunk"},
		leaves = {"moretrees:birch_leaves"},
		fruits = {"moretrees:birch_trunk"},
		trunk_fruit_vertical = true,
		cutting_leaves = 3,
		stem_height_min = 4,
		range = 8,
		range_down = 13,
		range_up = 10,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:fir_trunk"},
		leaves = {"moretrees:fir_leaves", "moretrees:fir_leaves_bright"},
		range_up = 2,
		range_down = 21,
		range = 7,
		fruits = {"moretrees:fir_cone", "moretrees:fir_trunk"},
		trunk_fruit_vertical = true
	}

	elefarm.tc.register_tree({
		trees = {"moretrees:jungletree_trunk"},
		leaves = {"moretrees:jungletree_leaves_green",
			"jungletree_leaves_yellow", "jungletree_leaves_red"},
		range = 8,
	})

	elefarm.tc.register_tree{
		trees = {"moretrees:oak_trunk"},
		leaves = {"moretrees:oak_leaves"},
		fruits = {"moretrees:acorn", "moretrees:oak_trunk"},
		trunk_fruit_vertical = true,
		stem_type = "+",
		range = 11,
		range_up = 11,
		range_down = 1,
	}

	-- needs special type
	elefarm.tc.register_tree({
		trees = {"moretrees:cedar_trunk"},
		leaves = {"moretrees:cedar_leaves"},
		range = 10,
		range_up = 1,
		range_down = 19,
		trunk_fruit_vertical = true,
		fruits = {"moretrees:cedar_cone", "moretrees:cedar_trunk"}
	})

	elefarm.tc.register_tree{
		trees = {"moretrees:rubber_tree_trunk",
			"moretrees:rubber_tree_trunk_empty"},
		leaves = {"moretrees:rubber_tree_leaves"},
		fruits = {"moretrees:rubber_tree_trunk",
			"moretrees:rubber_tree_trunk_empty"},
		trunk_fruit_vertical = true,
		stem_type = "2x2",
		range = 8,
		range_down = 1,
		range_up = 8,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:sequoia_trunk"},
		leaves = {"moretrees:sequoia_leaves"},
		fruits = {"moretrees:sequoia_trunk"},
		trunk_fruit_vertical = true,
		stem_type = "+",
		range = 10,
		range_up = 3,
		range_down = 33,
		cutting_leaves = 6,
		stem_height_min = 6,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:spruce_trunk"},
		leaves = {"moretrees:spruce_leaves"},
		fruits = {"moretrees:spruce_cone", "moretrees:spruce_trunk"},
		trunk_fruit_vertical = true,
		cutting_leaves = 1,
		stem_type = "+",
		range = 10,
		range_down = 25,
		range_up = 5,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:willow_trunk"},
		leaves = {"moretrees:willow_leaves"},
		fruits = {"moretrees:willow_trunk"},
		trunk_fruit_vertical = true,
		stem_type = "+",
		range = 13,
		range_up = 6,
		range_down = 6,
	}

	elefarm.tc.register_tree{ -- small and 2x2 jungletree at once
		trees = {"moretrees:jungletree_trunk"},
		leaves = {epi.jungle_leaves, "moretrees:jungletree_leaves_red"},
		fruits = {"moretrees:jungletree_trunk"},
		requisite_leaves = {"moretrees:jungletree_leaves_red"},
		trunk_fruit_vertical = true,
		stem_height_min = 4,
		cutting_leaves = 5,
		stem_type = "2x2",
		range = 8, -- 5 small
		range_up = 2, -- 1 small
		range_down = 17, -- 6 small
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:jungletree_trunk"},
		leaves = {epi.jungle_leaves, "moretrees:jungletree_leaves_yellow",
			"moretrees:jungletree_leaves_red"},
		fruits = {"moretrees:jungletree_trunk"},
		requisite_leaves = {"moretrees:jungletree_leaves_yellow"},
		trunk_fruit_vertical = true,
		cutting_leaves = 5,
		stem_type = "+",
		range = 8,
		range_up = 4,
		range_down = 16,
	}

	elefarm.tc.register_tree{
		trees = {"moretrees:palm_trunk"},
		trunk_top = "moretrees:palm_fruit_trunk",
		leaves = "moretrees:palm_leaves",
		fruit = "moretrees:coconut",
		range = 10,
		range_up = 7,
		range_down = 4,
		max_forbi = 2,
		type = "palm",
	}

	--~ elefarm.tc.register_tree({
		--~ trees = {"moretrees:sequoia_trunk"},
		--~ leaves = {"moretrees:sequoia_leaves"},
		--~ range = 8,


		--~ height = 17,
		--~ max_nodes = 8000,
		--~ num_trunks_min = 5,
		--~ num_trunks_max = 400,
		--~ num_leaves_min = 10,
		--~ num_leaves_max = 4000,
		--~ type = "moretrees",
	--~ })

	--~ elefarm.tc.register_tree({
		--~ trees = {"moretrees:willow_trunk"},
		--~ leaves = {"moretrees:willow_leaves"},
		--~ range = 11,
		--~ height = 17,
		--~ max_nodes = 8000,
		--~ num_trunks_min = 5,
		--~ num_trunks_max = 400,
		--~ num_leaves_min = 10,
		--~ num_leaves_max = 4000,
		--~ type = "moretrees",
	--~ })
end

-- code from amadin and narrnika
if minetest.get_modpath("ethereal") then
	elefarm.tc.register_tree({
		trees = {epi.jungle_tree},
		leaves = {epi.jungle_leaves},
		range = 3,
		height = 20,
		max_nodes = 145,
		num_trunks_min = 0,
		num_trunks_max = 35,
		num_leaves_min = 0,
		num_leaves_max = 110,
		type = "moretrees",
	})
	elefarm.tc.register_tree({
		trees = {"default:pinetree"}, -- this may need to be changed to pine_tree
		leaves = {"ethereal:pineleaves"},
		range = 6,
		type = "default",
	})
	elefarm.tc.register_tree({
		trees = {epi.tree},
		leaves = {epi.leaves, "ethereal:orange_leaves"},
		fruits = {epi.apple, "ethereal:orange"},
		range = 2,
		type = "default",
	})
	elefarm.tc.register_tree({
		trees = {"ethereal:acacia_trunk"},
		leaves = {"ethereal:acacia_leaves"},
		range = 10,
		height = 10,
		max_nodes = 122,
		num_trunks_min = 0,
		num_trunks_max = 22,
		num_leaves_min = 0,
		num_leaves_max = 100,
		type = "moretrees",
	})
	elefarm.tc.register_tree({
		trees = {"ethereal:banana_trunk"},
		leaves = {"ethereal:bananaleaves"},
		fruits = {"ethereal:banana"},
		range = 3,
		height = 7,
		max_nodes = 28,
		num_trunks_min = 0,
		num_trunks_max = 4,
		num_leaves_min = 0,
		num_leaves_max = 20,
		type = "moretrees",
	})
	elefarm.tc.register_tree({
		trees = {"ethereal:palm_trunk"},
		leaves = {"ethereal:palmleaves"},
		fruits = {"ethereal:coconut"},
		range = 3,
		height = 9,
		max_nodes = 37,
		num_trunks_min = 0,
		num_trunks_max = 8,
		num_leaves_min = 0,
		num_leaves_max = 25,
		type = "moretrees",
	})
	elefarm.tc.register_tree({
		trees = {"ethereal:willow_trunk"},
		leaves = {"ethereal:willow_twig"},
		range = 10,
		height = 13,
		max_nodes = 540,
		num_trunks_min = 0,
		num_trunks_max = 90,
		num_leaves_min = 0,
		num_leaves_max = 450,
		type = "moretrees",
	})
	elefarm.tc.register_tree({
		trees = {"ethereal:mushroom_trunk"},
		leaves = {"ethereal:mushroom", "ethereal:mushroom_porew"},
		range = 4,
		height = 10,
		max_nodes = 100,
		num_trunks_min = 0,
		num_trunks_max = 32,
		num_leaves_min = 0,
		num_leaves_max = 80,
		type = "moretrees",
	})
end