tMV

local xPos, zPos, yPos = 0, 0, 0
local movementArray = {}
local facing = 1

--constructing movementArray with the proper values for x, y increment based on facing
--array looks like |a11 a12 a13 a14|
--                 |a21 a22 a23 a24|
for facingInc=1,4 do
 movementArray[facingInc] = {}
	for xzInc=1,2 do
		movementArray[facingInc][xzInc] = 0
	end
end

--filling in proper values in movementArray
--row 1 is the z movement, row 2 is the x movement
movementArray[1][1] = 1
movementArray[1][2] = 0
movementArray[1][3] = -1
movementArray[1][4] = 0

movementArray[2][1] = 0
movementArray[2][2] = 1
movementArray[2][3] = 0
movementArray[2][4] = -1

--move turtle forward with tracking
function tForward()
	--print("moving forward")
	--print("curPos:"..xPos..yPos..zPos)
	if turtle.forward() then
		zPos = zPos + movementArray[1][facing]
		xPos = xPos + movementArray[2][facing]
		--print("moved")
		--print("newPos:"..xPos..yPos..zPos)
		return true
	else
		--print("could not move")
		return false
	end
end

--move turtle back with tracking
function tBack()
	--print("moving back")
	--print("curPos:"..xPos..yPos..zPos)
	if turtle.back() then
		zPos = zPos - movementArray[1][facing]
		xPos = xPos - movementArray[2][facing]
		--print("moved")
		--print("newPos:"..xPos..yPos..zPos)
		return true
	else
		--print("could not move")
		return false
	end
end

--turn turtle right with tracking
function tTurnRight()
	--print("turning Right")
	--print("curFac:"..facing)
	if turtle.turnRight() then
		if facing < 4 then
			facing = facing + 1
		elseif facing == 4 then
			facing = 1
		end
		--print("turned")
		--print("newFac:"..facing)
		return true
	else
		return false
	end
end

--turn turtle left with tracking
function tTurnLeft()
	--print("turning Left")
	--print("curFac:"..facing)
	if turtle.turnLeft() then
		if facing > 1 then
			facing = facing - 1
		elseif facing == 1 then
			facing = 4
		end
		--print("turned")
		--print("newFac:"..facing)
		return true
	else
		return false
	end
end

--move turtle up with tracking
function tUp()
	--print("moving up")
	--print("curElev:"..yPos)
	if turtle.up() then
		yPos = yPos + 1
		--print("moved up")
		--print("newElev:"..yPos)
		return true
	else
		--print("could not move up")
		return false
	end
end

--move turtle down with tracking
function tDown()
	--print("moving down")
	--print("curElev:"..yPos)
	if turtle.down() then
		yPos = yPos - 1
		--print("moved down")
		--print("newElev:"..yPos)
		return true
	else
	--print("could not move down")
		return false
	end
end

--faces a specified direction
function face(targetFacing)
	--print("turning to face new direction")
	--print("curFac:"..facing)
	while facing ~= targetFacing do
		tTurnRight()
	end
	--print("newFac:"..facing)
end

--move turtle back to position using tracking data
function moveToPos(targetRelPos)
	--print("moving to target position")
	--print("target pos:" .. targX .. targY .. targZ)
	local isOnTarget = false
	local stuckness = {}
	for i=1,3 do stuckness[i] = 0 end

	while not isOnTarget do
		--attemps to move towards origin, first in y, then z, then x.
		--	it it gets stuck, then the stuckness val is ++ and it
		--	will attempt to move away from 0 in one dimension to
		--	unstick itself
		--It does this after each axis normal movement to prevent
		--	immediate backtracking

		--normal attempts start with y axis
		if yPos < targetRelPos[2] then
			--print("I need to go up")
			if not tUp() then
				stuckness[2] = stuckness[2] + 1
				--print("stuckness:"..stuckness[2])
			end
		elseif yPos > targetRelPos[2] then
			--print("I need to go down")
			if not tDown() then
				stuckness[2] = stuckness[2] + 1
				--print("stuckness:"..stuckness[2])
			end
		end

		--if stuck for 3 cycles it will move opposite to normal to
		--	try to escape
		if stuckness[2] >= 3 then
			--print("Im stuck in the y axis")
			if yPos < targetRelPos[2] then
				if tDown() then
					--print("Ive moved down")
					stuckness[2] = 0
				end
			else
				if tUp() then
					--print("Ive moved up")
					stuckness [2] = 0
				end
			end
		end


		--then z axis
		if zPos > targetRelPos[3] then
			--print("I need to go south")
			face(3)
			if not tForward() then
				stuckness[3] = stuckness[3] + 1
				--print("stuckness:"..stuckness[3])
			end
		elseif zPos < targetRelPos[3] then
			--print("I need to go north")
			face(1)
			if not tForward() then
				stuckness[3] = stuckness[3] + 1
				--print("stuckness:"..stuckness[3])
			end
		end

		--if stuck for 3 cycles it will move opposite to normal to
		--	try to escape
		if stuckness[3] >= 3 then
			--print("Im stuck in the z axis")
			if tBack() then
				--print("Ive moved back")
				stuckness[3] = 0
			end
		end


		--then x axis
		if xPos > targetRelPos[1] then
			--print("I need to go west")
			face(4)
			if not tForward() then
				stuckness[1] = stuckness[1] + 1
				--print("stuckness:"..stuckness[1])
			end
		elseif xPos < targetRelPos[1] then
			--print("I need to go east")
			face(2)
			if not tForward() then
				stuckness[1] = stuckness[1] + 1
				--print("stuckness:"..stuckness[1])
			end
		end

		--if stuck for 3 cycles it will move opposite to normal to
		--	try to escape
		if stuckness[1] >= 3 then
			--print("Im stuck in the x axis")
			if tBack() then
				--print("Ive moved back")
				stuckness[1] = 0
			end
		end


		if (xPos == targetRelPos[1] and yPos == targetRelPos[2]	and zPos == targetRelPos[3]) then
			isOnTarget = true
		end
	end
end

--returns to the original start location
function goHome()
	moveToPos({0,0,0})
end

--returns current coordinates
function getPos()
	return({xPos, yPos, zPos})
end

--returns current facing
function getFacing()
	return(facing)
end