[Lua][Question][Turtle]return to a starting point after running around w/o GPS

--This section sets the variables. WARNING, THESE ARE GLOBAL VARIABLES!!!!--
store, fuel, torches, sand, gravel, dirt, stone = 1, 2, 3, 4, 5, 6, 7
ore = false
--x is "left/right" w/ left = +
--y is "forward/back" w/ forward = +
--z is "up/down" w/ up = +
front, left, rear, right = 0,1,2,3
x, y, z, o = 0,0,0,0 --Current Co-ordinates
xo,yo,zo,oo = 0,0,0,0 --Origin Point, where the turtle starts the program
xb,yb,zb,ob = 0,0,0,0 --Saved Co-ordinates, where the turtle goes back to betwwen routines

function turn() --just keep turning, turning, turning
turtle.turnLeft()
o = o + 1
end
function ff() --short for "Face-Forward"
while (o)%4 ~= 0 do
turn()
end
end
function fl() --"face-left"
while (o)%4 ~= 1 do
turn()
end
end
function fb() --"face-back"
while (o)%4 ~= 2 do
turn()
end
end
function fr() --"face-right"
while (o)%4 ~= 3 do
turn()
end
end

--Actual Movement functions below this line.
function forward()
ff()
turtle.dig()
turtle.forward()
y = y + 1
end
function left()
fl()
turtle.dig()
turtle.forward()
x = x +1
end
function back()
fb()
turtle.dig()
turtle.forward()
y = y - 1
end
function right()
fr()
turtle.dig()
turtle.forward()
x = x - 1
end
function up()
turtle.digUp()
turtle.up()
z = z + 1
end
function down()
turtle.digDown()
turtle.down()
z = z - 1
end

--Go back functions
function savearea() --The all important reference point, tells the turtle to go back to this spot when used
xb,yb,zb,ob = x,y,z,o
end

function goback()
while xb ~= x do
if xb > x then
right()
end
if xb < x then
left()
end
end
while yb ~= y do
if yb > y then
back()
end
if yb < y then
forward()
end
end
while zb ~= z do
if zb > z then
down()
end
if zb < z then
up()
end
end
while ob ~= o do
turn()
end
end

--Checks surrounding blocks against "noise" inventory
function checkforward()
	ff()
if turtle.detect() then
turtle.select(stone)
if turtle.compare() == false then
turtle.select(dirt)
  if turtle.compare() == false then
  turtle.select(gravel)
   if turtle.compare() == false then
   turtle.select(sand)
	if turtle.compare() == false then
	 ore = true
   end
  end
end
end
end
end

function checkleft()
	fl()
if turtle.detect() == true then
turtle.select(stone)
if turtle.compare() == false then
  turtle.select(dirt)
  if turtle.compare() == false then
   turtle.select(gravel)
   if turtle.compare() == false then
	turtle.select(sand)
	if turtle.compare() == false then
	 ore = true
	end
   end
  end
end
end
end

function checkback()
fb()
if turtle.detect() == true then
turtle.select(stone)
if turtle.compare() == false then
  turtle.select(dirt)
  if turtle.compare() == false then
   turtle.select(gravel)
   if turtle.compare() == false then
	turtle.select(sand)
	if turtle.compare() == false then
	 ore = true
	end
   end
  end
end
end
end

function checkright()
fr()
if turtle.detect() == true then
turtle.select(stone)
if turtle.compare() == false then
  turtle.select(dirt)
  if turtle.compare() == false then
   turtle.select(gravel)
   if turtle.compare() == false then
	turtle.select(sand)
	if turtle.compare() == false then
	 ore = true
	end
   end
  end
end
end
end

function checkup()
if turtle.detectUp() == true then
turtle.select(stone)
if turtle.compareUp() == false then
  turtle.select(dirt)
  if turtle.compareUp() == false then
   turtle.select(gravel)
   if turtle.compareUp() == false then
	turtle.select(sand)
	if turtle.compareUp() == false then
	 ore = true
	end
   end
  end
end
end
end

function checkdown()
if turtle.detectDown() == true then
turtle.select(stone)
if turtle.compareDown() == false then
  turtle.select(dirt)
  if turtle.compareDown() == false then
   turtle.select(gravel)
   if turtle.compareDown() == false then
	turtle.select(sand)
	if turtle.compareDown() == false then
	 ore = true
	end
   end
  end
end
end
end

--The "Smart Mine" functions

function deepmine()
	checkforward()
if ore == true then
	forward()
	ore = false
	deepmine()
else checkup()
	if ore == true then
	up()
	ore = false
	deepmine()
else checkdown()
	if ore == true then
	down()
	ore = false
	deepmine()
else checkleft()
	if ore == true then
	left()
	ore = false
	deepmine()
else checkback()
	if ore == true then
	back()
	ore = false
	deepmine()
else checkright()
	if ore == true then
	right()
	ore = false
	deepmine()
	end
end
end
end
end
end
goback()
end

function checkrabbit()
print("rabbit?")
checkforward()
print("check forward")
if ore == true then
	forward()
	ore = false
	deepmine()
else
print("Left?")
checkleft()
print("Check Left")
	if ore == true then
	left()
	ore = false
	deepmine()
else checkback()
	if ore == true then
	back()
	ore = false
	deepmine()
else checkright()
	if ore == true then
	right()
	ore = false
	deepmine()
end
end
end
end
end

function checktunnel()
checkup()
if ore == true then
	forward()
	ore = false
	deepmine()
else checkleft()
	if ore == true then
	left()
	ore = false
	deepmine()
else checkright()
	if ore == true then
	right()
	ore = false
	deepmine()
end
end
end
end

function checkreturn()
	checkdown()
	if ore == true then
	down()
	ore = false
	deepmine()
else checkleft()
	if ore == true then
	left()
	ore = false
	deepmine()
else checkright()
	if ore == true then
	right()
	ore = false
	deepmine()
end
end
end
end

--Functions Actually to be used
function start()
term.clear()
term.setCursorPos(1,1)
print("Please place two unique enderchests in the last two slots, then torches, sand, gravel, dirt, and stone.")
write("How far down should I go? ")
depth = tostring( read())
write("How far forward should I go? ")
length = tostring( read())
end

function rabbithole()
for i=1,depth do
savearea()
print("lets mine")
checkrabbit()
down()
end
end

function tunnel()
for i=1,length do
savearea()
checktunnel()
forward()
turtle.digDown()
end
end

function rere()
down()
for i = 1,length do
savearea()
back()
checkreturn()
end
for i = 1,depth do
savearea()
up()
end
while ob ~= o do
turn()
end
end

--Finally, the end of this crap
start()
rabbithole()
tunnel()
rere()