pos.lua

local V = vector.new
local R = function(v, r)
    local f = r > 1 and -1 or 1
    if r % 2 == 1 then
        return V(-v.z * f, v.y, v.x * f)
    end
    return V(v.x * f, v.y, v.z * f)
end


moveUpdates = {
    forward = {1, 0, 0, 0},
    back = {-1, 0, 0, 0},
    turnLeft = {0, 0, 0, -1},
    turnRight = {0, 0, 0, 1},
    up = {0, 1, 0, 0},
    down = {0, -1, 0, 0}
}

function savePos()
    local h = fs.open("/.pos", "w")
    h.write(textutils.serialize(turtle.pos))
    h.close()
    --print(unpack(turtle.pos))
end

function loadPos()
    local h = fs.open("/.pos", "r")
    if h ~= nil then
        turtle.pos = textutils.unserialize(h.readAll())
        h.close()
        term.setTextColor(0x100)
        term.write("current position is: ")
        term.setTextColor(0x2000)
        print(turtle.pos[1], turtle.pos[2], turtle.pos[3], string.sub("ESWN", turtle.pos[4] + 1, turtle.pos[4] + 1))
        term.setTextColor(0x100)
        print("if incorrect, 'rm /.pos' and reboot")
        term.setTextColor(1)
    else
        local p = {}
        term.setTextColor(0x2000)
        print("Please enter turtle coordinates")
        term.setTextColor(1)
        term.write("x: ")
        p[1] = tonumber(read())
        assert(p[1] ~= nil)
        term.write("y: ")
        p[2] = tonumber(read())
        assert(p[2] ~= nil)
        term.write("z: ")
        p[3] = tonumber(read())
        assert(p[3] ~= nil)
        term.write("orientation (N/E/S/W): ")
        local ori = string.upper(read())
        if ori == "E" then
            p[4] = 0
        elseif ori == "S" then
            p[4] = 1
        elseif ori == "W" then
            p[4] = 2
        elseif ori == "N" then
            p[4] = 3
        end
        assert(p[4] ~= nil)
        turtle.pos  = p
        savePos()
    end
end


term.clear()
term.setCursorPos(1, 1)
loadPos()

for k, move in pairs(moveUpdates) do
    local fn = turtle[k]
    turtle[k] = function()
        local oldPos = turtle.pos
        local posV = V(unpack(oldPos)) + R(V(unpack(move)), oldPos[4])
        turtle.pos = { posV.x, posV.y, posV.z, (oldPos[4] + 4 + move[4]) % 4 }
        savePos()
        local r = fn()
        if not r then
            turtle.pos = oldPos
            savePos()
        end
        return r
    end
end