computer-craft/py_tree

-- will make a pythagoras tree-like thing with a given depth (depth 0 are leaves)
-- this is a costy operation and takes lots of blocks (you can refill during the build)
-- we will always face to the tree and not move forward
-- orientation will define left/right/up/down

-- basic movement (orientation-less)
local function bup()
	while not turtle.up() do turtle.digUp() end
end

local function bdown()
	while not turtle.down() do turtle.digDown() end
end

local function bforward()
	while not turtle.forward() do turtle.dig() end
end

local function bleft()
	turtle.turnLeft()
	bforward()
	turtle.turnRight()
end

local function bright()
	turtle.turnRight()
	bforward()
	turtle.turnLeft()
end

local function select_non_empty( )
	for i = 1, 9 do
		if turtle.getItemCount(i) > 0 then
			turtle.select(i)
			return
		end
	end

	turtle.select(1)
	print("ERROR: I'm empty, plz refill me!")
	while turtle.getItemCount(1) == 0 do sleep(2) end
end

local function place()
	select_non_empty()
	turtle.place()
end

-- basic orientation operations
local function toleft( orientation )
	return (orientation + 3) % 4
end

local function toback( orientation )
	return (orientation + 2) % 4
end

local function toright( orientation )
	return (orientation + 1) % 4
end

-- basic movement (with orientation)
local function forward( orientation )
	if orientation == 0 then bup()
	elseif orientation == 1 then bright()
	elseif orientation == 2 then bdown()
	elseif orientation == 3 then bleft()
	else print("Error, wrong orientation")
	end
end

-- TODO: make more efficient, we are not placing blocks...
local function walk( orientation, n )
	for i = 1, n do
		forward(orientation)
	end
end

-- stops after the line
local function line( orientation, n )
	for i = 1, n do
		place()
		forward(orientation)
	end
end

-- stops after the rect
local function fill( w, h, orientation )
	print(" fill "..w.."x"..h.." in orientation "..orientation)
	if w == 1 then
		line(orientation, h)
		return
	end
	for i = 1, h do
		if i % 2 == 1 then line(toright(orientation), w - 1)
		else line(toleft(orientation), w - 1) end
		place()
		forward(orientation)
	end
end

local function tree( depth, orientation )
	print("Start with "..depth.." in orientation "..orientation)
	-- done with recursion
	if depth == 0 then
		place()
		walk(toback(orientation), 1)
		return
	end

	local n = 2^depth
	local half = n/2
	local w = n
	local h = n + half

	-- big chunk, if needed move to left
	fill(w, h, orientation)
	if h % 2 == 1 then
		walk(toleft(orientation), w - 1)
	end

	walk(toleft(orientation), 1)
	line(toleft(orientation), half)

	-- first branch (left)
	tree(depth - 1, toleft(orientation))
	line(orientation, half)

	-- second branch (left)
	tree(depth - 1, orientation)

	-- fill between branches
	if half - 1 > 0 then
		forward(toright(orientation))
		fill(half - 1, half - 1, toright(orientation))
	else
		walk(toright(orientation), 1)
	end

	-- walk to right branches
	walk(toright(orientation), w)

	-- fill between branches
	if half - 2 > 0 then
		fill(half - 1, half - 2, orientation)
	end
	walk(orientation, 1)

	-- first branch
	tree(depth - 1, orientation)
	line(toright(orientation), half)

	-- second branch
	tree(depth - 1, toright(orientation))
	line(toback(orientation), half - 1)
	line(toleft(orientation), half)

	-- move back to pre-begin
	walk(toback(orientation), h)
	walk(toleft(orientation), w - 1)
	walk(toback(orientation), 1)
end

local args = { ... }
tree(args[1], 0)