dualstick

--The width and height of the screen
local w,h = term.getSize()
--Whether or not the game is running
local running = true
--The interval between each game update
local refreshRate = 0.15
--The game update timer
local gtID = os.startTimer(refreshRate)

--Header for updateBullets function
local updateBullets = nil

--[[ Our player:
  x: his X position
  y: his Y position
  icon: the icon drawn at his position
  rotation: the player facing
]]--
local player = {
  x = math.floor(w/2),
  y = math.floor(h/2),
  icon = "&",
  rotation = 0.0
}

--[[ The list of bullets:
  x: the x position
  y: the y position
  xstep: the movement each update on x
  ystep: the movement each update on y
  type: the colour of the bullet
]]--
local bullets = { }
--The list of all possible bullet types
local bullTypes = { colours.orange, colours.yellow, colours.lime }
--The currently selected bullet type
local selBull = 1

--Draws the player, bullets and header info
local function display()
  -- Player draw code
  term.setBackgroundColour(colours.black)
  term.clear()
  term.setTextColour(colours.lime)
  term.setCursorPos(player.x, player.y)
  term.write(player.icon)

  -- Footer draw code
  term.setCursorPos(1,h)
  term.setBackgroundColour(bullTypes[selBull])
  term.write(string.rep(" ", w))

  -- Bullet draw code
  for _,v in pairs(bullets) do
    term.setCursorPos(v.x, v.y)
    term.setBackgroundColour(v.type)
    term.write(" ")
  end

  -- Reticle code

  term.setCursorPos(player.x + math.cos(player.rotation) * 8,
      player.y - math.sin(player.rotation) * 6)
  term.setBackgroundColour(colours.black)
  term.setTextColour(colours.green)
  term.write("+")

end

local function createBullet(x,y,xvel,yvel)
  table.insert(bullets, {
    x = x,
    y = y,
    xstep = xvel,
    ystep = yvel,
    type = bullTypes[selBull]
  })
end

--Accepts and acts upon input (and timers)
local function handleInput()
  local id, p1, p2, p3 = os.pullEvent()

  if id == "key" then

  elseif id == "mouse_click" or id == "mouse_drag" then

  elseif id == "mouse_scroll" then

  end

  if id == "timer" and p1 == gtID then
    updateBullets()
    gtID = os.startTimer(refreshRate)
  end
end

--Moves each bullet according to their velocity,
--and removes those that have left the screen
function updateBullets()
  for _,v in pairs(bullets) do
    v.x = v.x + v.xstep
    v.y = v.y + v.ystep
  end

  local blistlength = #bullets
  for i=1,blistlength do
    local v = bullets[i]
    if v and (v.x < 1 or v.x > w or
       v.y < 1 or v.y > h-1) then
      table.remove(bullets, i)
      blistlength = blistlength - 1
      i = i - 1
    end
  end
end

--The main game loop
local function mainLoop()
  while running do
    display()
    handleInput()
  end
end

mainLoop()