Code Structure Guide

As your game grows, keeping your Lua code organized becomes important. This page shows recommended patterns for structuring larger projects.

Basic structure

For small games, the three lifecycle functions are enough:

function _init()
  -- set up everything
end

function _update()
  -- all game logic
end

function _draw()
  clear(0)
  -- all rendering
end

Organized structure

As your game grows, break each lifecycle function into smaller, focused functions:

function _init()
  init_player()
  init_level()
  init_enemies()
end

function _update()
  update_player()
  update_enemies()
  update_camera()
end

function _draw()
  clear(0)
  draw_level()
  draw_enemies()
  draw_player()
  draw_ui()
end

This pattern scales well because:

• Each function has a single responsibility

• You can easily find and modify specific behavior

• Adding new systems (pickups, particles, menus) means adding new functions without touching existing ones

Naming conventions

Use consistent naming to keep your code readable:

-- Constants in UPPER_CASE
SPRITE_PLAYER = 0
PLAYER_SPEED = 2
GRAVITY = 0.3

-- Game objects as tables
player = {}
enemies = {}
bullets = {}

-- Functions named by what they do
function init_player() ... end
function update_player() ... end
function draw_player() ... end

Game state management

For games with multiple screens (menu, gameplay, game over), use a state variable:

state = "menu"

function _update()
  if state == "menu" then
    update_menu()
  elseif state == "play" then
    update_game()
  elseif state == "gameover" then
    update_gameover()
  end
end

function _draw()
  clear(0)
  if state == "menu" then
    draw_menu()
  elseif state == "play" then
    draw_game()
  elseif state == "gameover" then
    draw_gameover()
  end
end