goto.lua file for turtle movement in ComputerCraft

-- Code from PhyscoKillerMonkey post at http://www.computercraft.info/forums2/index.php?/topic/5665-wireless-goto-program-for-gps-turtles/page__fromsearch__1


rednet.open("right") --Open rednet and clear the console
term.clear()
term.setCursorPos(1,1)
local tArgs = { ... } --Get the coordinates from alongside the program launch (goto x y z)
local gox = tonumber(tArgs[1])
local goy = tonumber(tArgs[2])
local goz = tonumber(tArgs[3])
if #tArgs ~= 3 then --Make sure there are 3 coordinates entered else the program will return an error
print("Usage: goto <x> <y> <z>")
end
local digBlocks = false --Extra parameters: whether to dig blocks or attempt to go over
local goneUp = 0 --dir and goneUp are used to keep track of position
local dir = 0
function forward()
while not turtle.forward() do --If turtle cannot go forward (either out of fuel or block blocking)
print("Can't move, checking fuel")
  if turtle.getFuelLevel() == 0 then
   turtle.select(1)
   turtle.refuel(1)
  end
  if digBlocks then --If digBlocks var was true the turtle will dig thorugh the blockage otherwise will go over
   turtle.dig()
  else
   turtle.up()
   goneUp = goneUp + 1
  end
end
while goneUp > 0 and not turtle.detectDown() do --Make sure to compensate for going up and over blocks by going down when next possible
  turtle.down()
  goneUp = goneUp - 1
end
end
function up() --Same as forward, for up
while not turtle.up() do
print("Can't move, checking fuel")
  if turtle.getFuelLevel() == 0 then
   turtle.select(1)
   turtle.refuel(1)
  end
  if digBlocks then
   turtle.digUp()
  end
end
end
function down() --Same as forward, for down
while not turtle.down() do
print("Can't move, checking fuel")
  if turtle.getFuelLevel() == 0 then
   turtle.select(1)
   turtle.refuel(1)
  end
  if digBlocks then
   turtle.digDown()
  end
end
end
function getPos() --Gets the position of the turtle from local GPS towers
print("Getting position")
cx, cy, cz = gps.locate(10)
print(cx, cy, cz)
end
function getDir() --Gets the heading of the turtle by taking position, moving forward 1 and comparing the 2 positions
print("Getting direction")
getPos()
ox, oy, oz = cx, cy, cz
forward()
getPos()
if oz > cz then dir = 0
elseif oz < cz then dir = 2
elseif ox < cx then dir = 1
elseif ox > cx then dir = 3 end
print(dir)
turtle.back()
getPos()
end
function turn(d) --Turns to heading "d", uses getDir() to calculate how many turns are needed
getDir()
print("Aligning")
print(dir, d)
while dir ~= d do
  turtle.turnRight()
  dir = dir + 1
  if dir == 4 then dir = 0 end
end
end
function moveX() --Combine the past functions to move along the x axis
print("Moving X")
getPos()
if gox > cx then --The current and destination coordinates are compared to decide which heading is needed and distance to move
  turn(1)
  for x = 1, gox - cx do
   forward()
   cx = cx + 1
  end
elseif gox < cx then
  turn(3)
  for x = 1, cx - gox do
   forward()
   cx = cx - 1
  end
end
end
function moveZ() --The same as moveX() but for the Z axis
print("Moving Z")
getPos()
if goz > cz then
  turn(2)
  for z = 1, goz - cz do
   forward()
   cz = cz + 1
  end
elseif goz < cz then
  turn(0)
  for z = 1, cz - goz do
   forward()
   cz = cz - 1
  end
end
end
function moveY() --The same as moveX() but for the Y axis, as the movement is vertical no turn calculations are needed so this function is shorter
print("Moving Y")
getPos()
if goy > cy then
  for z = 1, goy - cy do
   up()
   cy = cy + 1
  end
elseif goy < cy then
  for z = 1, cy - goy do
   down()
   cy = cy - 1
  end
end
end
getPos()
if goy > cy then --If the turtle has to move upwards to get to the destination if moves up first, if it needs to move down if moves down last
moveY()
moveX()
moveZ()
else
moveX()
moveZ()
moveY()
end