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GGCode Scripting System

Welcome to GGCode's scripting documentation! This system lets you create custom client and server plugins for MU Online using LuaJIT.

Whether you're building a simple reward window or a complex gameplay mechanic, everything you need is here.

Documentation Status

This documentation is actively maintained and updated. Found an issue or something unclear?

Contact GGCode Support - we'll fix it quickly and improve the docs for everyone.

What's Covered​

Client Side​

Build user interfaces, handle input, communicate with the server.

Topics:

  • UI Windows - create and position windows
  • UI Rendering - draw colors, text, images, items
  • UI Components - buttons, text inputs, slots
  • Input System - mouse and keyboard
  • Network Events - server communication
  • Utilities - HTTP, JSON, sounds, logs

Server Side​

Manage players, control game logic, work with databases.

Topics:

  • Player Functions - stats, positions, currency
  • Items & Monsters - inventory, spawning
  • Database & Events - SQL and game events
  • Utilities - commands, effects, party/guild

Working Examples​

Complete, ready-to-use plugins you can learn from.

  • Daily Reward System - basic plugin with database
  • Teleport System - advanced UI with scrolling lists

The Essential Rules​

1. Packet IDs Must Match​

Client and server must use identical packet IDs:

// Client
PluginPacket.MyPlugin = 15100

// Server
PluginPacket.MyPlugin = 15100  -- Same ID!

Always use IDs >= 15000 to avoid game conflicts.

2. Validate in SQL Callbacks​

Players can disconnect while SQL runs. Always check:

SQLQuery(query, function(q)
    -- Is player still online?
    if GetObjectConnected(aIndex) ~= OBJECT_ONLINE then
        return
    end

    -- Name still matches?
    if GetObjectName(aIndex) ~= playerName then
        return
    end

    -- Safe to proceed
end)

3. Connection States​

OBJECT_OFFLINE = 0    -- Disconnected
OBJECT_CONNECTED = 1  -- Connected
OBJECT_LOGGED = 2     -- Logged in
OBJECT_ONLINE = 3     -- In game ← Use this!

Always check for OBJECT_ONLINE.

4. UI Groups​

UI_GROUP_SERVER = 0  -- Server select
UI_GROUP_SELECT = 1  -- Character select
UI_GROUP_INGAME = 2  -- In game ← Most common

Quick Tips​

Client:

packet:free()  -- Always free packets!
LogPrint("[MyPlugin] Debug info")
if not InputCheckChatOpen() then
    -- Process hotkeys
end

Server:

LogColor(2, "[MyPlugin] Success!")  -- Colored logs
SetObjectStrength(aIndex, 5000)
UserCalcAttribute(aIndex)  -- Recalculate!
UserInfoSend(aIndex)  -- Update client!

Basic Plugin Structure​

-- CLIENT
MyPlugin = {
    index = GetWindowIndex(),
    group = UI_GROUP_INGAME,
}

PluginPacket.MyPlugin = 15100

BridgeFunction:push("OnLoad", function()
    -- Create UI
end)

MagicWorld:pushRecv(PluginPacket.MyPlugin, function(packet)
    -- Handle server data
    packet:free()
end)

-- SERVER
MyPlugin = {}
MyPlugin.ScriptVersion = "1.0.0"

PluginPacket.MyPlugin = 15100

BridgeFunction:push("OnLoadScript", function()
    -- Initialize
end)

MagicWorld:pushRecv(PluginPacket.MyPlugin, function(aIndex, packet)
    -- Handle client request
end)

How to Learn​

New to this?

  1. Start with UI Windows guide
  2. Try the Daily Reward example
  3. Read Player Functions guide
  4. Build your own plugin

Already know Lua? Jump to the examples and use the guides as reference.

Debugging​

Client:

LogPrint("Debug: " .. tostring(value))
NoticeSend(1, "Debug message")

Server:

LogColor(3, "Debug info")
NoticeSend(aIndex, 1, "Message")

LuaJIT Limits​

  • No goto statements
  • Watch upvalues in large loops
  • Limit closures in SQL callbacks
  • Prefer local tables

Where to Start?​

Pick what you need:

  • Creating UI? → Client Side guides
  • Game logic? → Server Side guides
  • Learn by doing? → Examples section

All guides have working code you can use right away.

Maintained by GGCode | Updated regularly with community feedback