Turtle Movement Engine

-- f, b, l, r, u, d

-- 44, 64, -10

-- 39, 64, -10

-- localX 0
-- localY 5

-- f f f f l f f f l f f r f f l f f

-- r f f f f l l r

-- 0, 4

-- 0, -4

--   A +x
--   l
-- <-o->
-- -yl +y
--   V -x

-- Calculate f / r from where you stand. It's all relative to your direction. Important that we keep note of each turn.

function travelLogCalc(log)

    localX = 0
    localY = 0
    localZ = 0

    -- px, py, mx, my
    -- north, east, south, west
    directions = {1, 1, -1, -1}
    dir = 0
    -- Calculate fasted route to travel
    for i = #log, 1, -1 do
        currentDir = (dir % 4) + 1

        move = log[i]

        if move == "f" then
            if currentDir == 1 or currentDir == 3 then
                localX = localX - directions[(currentDir % 4) + 1]
            elseif currentDir == 2 or currentDir == 4 then
                localY = localY - directions[(currentDir % 4) + 1]
            end
        elseif move == "b" then
            if currentDir == 1 or currentDir == 3 then
                localX = localX + directions[(currentDir % 4) + 1]
            elseif currentDir == 2 or currentDir == 4 then
                localY = localY + directions[(currentDir % 4) + 1]
            end
        elseif move == "r" then
            dir = dir + 1
        elseif move == "l" then
            dir = dir - 1
        elseif move == "u" then
            localZ = localZ - 1
        elseif move == "d" then
            localZ = localZ + 1
        end
    end
    return { localX, localY, localZ, dir }
end

function travelEngine(args)
  log = {}
  localX = args[1]
  localY = args[2]
  localZ = args[3]
  -- we skip adding one since we already have turned to the right
  lookAtDir = (args[4] % 4) + 1

  turtle.turnRight()
  table.insert(log, "r")
  if localY > 0 then
    for i = 1, localY do
      if turtle.forward() then
        table.insert(log, "f")
      end
    end
  elseif localY < 0 then
    -- invert localY
    localY = -localY
    for i = 1, localY do
      if turtle.back() then
        table.insert(log, "b")
      end
    end
  end
  turtle.turnLeft()
    table.insert(log, "l")
  if localX > 0 then
    for i = 1, localX do
      if turtle.forward() then
        table.insert(log, "f")
      end
    end
  elseif localX < 0 then
    -- invert localX
    localX = -localX
    for i = 1, localX do
      if turtle.back() then
        table.insert(log, "b")
      end
    end
  end
  if localZ > 0 then
    for i = 1, localZ do
      if turtle.up() then
        table.insert(log, "u")
      end
    end
  elseif localZ < 0 then
    localZ = -localZ
    for i = 1, localZ do
      if turtle.down() then
        table.insert(log, "d")
      end
    end
  end
  -- This is a little scuffed
  turtle.turnLeft()
  table.insert(log, "l")
  for i = 1, lookAtDir do
    turtle.turnRight()
    table.insert(log, "r")
  end
  return log
end


function createTravelLog()
    log = {}
    for i = 1, 3 do
        if turtle.forward() then
            table.insert(log, "f")
        end
    end
    turtle.turnRight()
    table.insert(log, "r")
    turtle.forward()
    table.insert(log, "f")
    turtle.turnRight()
    table.insert(log, "r")
    for i = 1, 2 do
        if turtle.forward() then
            table.insert(log, "f")
        end
    end
    --[[
    turtle.turnLeft()
    table.insert(log, "l")
    turtle.forward()
    table.insert(log, "f")
    turtle.turnLeft()
    table.insert(log, "l")
    for i = 1, 3 do
        if turtle.forward() then
            table.insert(log, "f")
        end
    end
    --]]
    return log
end

-- travelLog = {"f", "f", "f", "f", "f", "f", "f", "r", "f","r", "f", "f", "f", "f", "f", "f", "f", "l", "f","l", "f", "f", "f", "f", "f", "f", "f"}

travelLog = createTravelLog()
print(table.concat(travelLog,", "))
cords = travelLogCalc(travelLog)
--print(table.concat(cords,", "))
wayBack = travelEngine(cords)
cords2 = travelLogCalc(wayBack)
print(table.concat(wayBack, ", "))
print(table.concat(cords2, ", "))
travelEngine(cords2)