arbitrarily changed version

local modules = peripheral.wrap "back"

local function length(x, y, z)
    return math.sqrt(x * x + y * y + z * z)
end

local function round(num, dp)
    local mult = 10^(dp or 0)
    return math.floor(num * mult + 0.5) / mult
end

local canvas = modules.canvas()

-- Backported from Opus Neural ElytraFly since it has a nicer implementation than I do
local function display(meta)
  if canvas then
    local w, h = canvas.getSize()
    if not canvas.group then
      canvas.group = canvas.addGroup({ w - 80, 15 })
      canvas.group.addRectangle(0, 0, 60, 30, 0x00000033)
      canvas.pitch = canvas.group.addText({ 4, 5 }, '') -- , 0x202020FF)
      canvas.pitch.setShadow(true)
      canvas.pitch.setScale(.75)
      canvas.group2 = canvas.addGroup({ w - 10, 15 })
      canvas.group2.addLines(
        { 0,   0 },
        { 0, 180 },
        { 5, 180 },
        { 5,   0 },
        0x202020FF,
        2)
      canvas.meter = canvas.group2.addRectangle(0, 0, 5, 1)
    end
    local size = math.abs(meta.pitch) -- math.ceil(math.abs(meta.pitch) / 9)
    local y = 0
    local color = 0x202020FF
    if meta.pitch < 0 then
      y = size
      color = 0x808080FF
    end
    canvas.meter.setPosition(0, 90 - y)
    canvas.meter.setSize(5, size)
    canvas.meter.setColor(color)
    local my = meta.motionY
    if not meta.isInWater then my = my + 0.0784 end
    canvas.pitch.setText(string.format('%s\nMotion Y: %s\nSpeed: %s',
      _G.flight_mode or "normal",
      round(my, 2),
      round(length(meta.motionX, my, meta.motionZ), 2)))
  end
end

--[[
local function pad(s, i)
    return ("%s %s%.1f"):format(s, i >= 0 and "+" or "", i)
end

local overlay = {
    function(meta) return pad("X:", meta.motionX) end,
    function(meta) return pad("Y:", meta.motionY) end,
    function(meta) return pad("Z:", meta.motionZ) end,
    function(meta) return pad("  ", length(meta.motionX, meta.motionY, meta.motionZ)) end,
    function(meta) return pad("P:", meta.power) end
}

local objects
local function draw_overlay(meta)
    if not objects then
        objects = {}
        local w, h = canv.getSize()
        for ix in pairs(overlay) do
            objects[ix] = canv.addText({w - 40, ix * 10 + 5}, "")
            objects[ix].setColor(0xFFFFFFFF)
        end
    end
    for ix, f in pairs(overlay) do
        objects[ix].setText(f(meta))
    end
end
]]

local function get_power(meta)
    local power = 4
    if meta.isElytraFlying or meta.isFlying then power = 1 end
    if meta.isSneaking then power = 4 end
    if _G.tps then
        power = power * (20 / _G.tps)
    end
    return math.min(power, 4)
end

local function get_meta()
    local meta = modules.getMetaByName "gollark"
    meta.power = get_power(meta)
    display(meta)
    return meta
end

local function calc_yaw_pitch(v)
    local x, y, z = v.x, v.y, v.z
    local pitch = -math.atan2(y, math.sqrt(x * x + z * z))
    local yaw = math.atan2(-x, z)
    return math.deg(yaw), math.deg(pitch)
end

local x, y, z

local function run()
while true do
    local meta = get_meta()

    while (not _G.stop_flight) and (meta.isSneaking or meta.isFlying or meta.isElytraFlying) do
        local mode = _G.flight_mode or "normal"
        print(mode)
        if mode == "normal"  then
            modules.launch(meta.yaw, meta.pitch, meta.power)
        elseif mode == "brake" then
            local vel = vector.new(meta.motionX, meta.motionY, meta.motionZ)
            local y, p = calc_yaw_pitch(-vel)
            modules.launch(y, p, math.min(vel:length(), 4))
        elseif mode == "align" and y then
            print(256 - y)
            local tdir = vector.new(-math.sin(math.rad(meta.yaw)), 0.1 * math.pow(256 - y, 3) / math.abs(256 - y), math.cos(math.rad(meta.yaw)))
            print(tdir)
            local y, p = calc_yaw_pitch(tdir)
            modules.launch(y, p, meta.power)
        end
        sleep(0.1)
        meta = get_meta()
    end

    if meta.motionY < -0.4 then
        modules.launch(0, 270, meta.power / 2)
        print("boost")
    end

    sleep(0.4)
end
end

local function do_gps()
    while true do
        x, y, z = gps.locate()
        sleep(0.2)
    end
end

parallel.waitForAll(do_gps, run)