How YimMenuV2's Network Module Handles Scripted Game Events (ScriptEvent)

YimMenuV2 processes Lua script events by validating arguments, packing them into a fixed 40-slot buffer, and dispatching them through the native GTA V function _SEND_TU_SCRIPT_EVENT_NEW.

The YimMenuV2 GTA V mod menu exposes low-level network scripting capabilities to Lua through its Network library. When developers need to trigger in-game script events—also known as TU Script Events—the module bridges the high-level Lua API with the game's native scripting engine. This article examines the exact implementation in src/game/scripting/libraries/Network.cpp to show how trigger_script_event marshals data from Lua scripts into the GTA V network layer.

The trigger_script_event Implementation

The trigger_script_event function serves as the primary interface for firing scripted game events. Located in src/game/scripting/libraries/Network.cpp, this function accepts an event hash, a player bitmask, a format string, and variable arguments before constructing the native event packet.

Argument Parsing and Validation

The function begins by extracting three mandatory parameters from the Lua stack. It retrieves the event hash (first argument), the target player mask (second argument), and the format string (third argument) that describes subsequent argument types.

auto hash = GetHashArgument(state, 1);
int bits = luaL_checkinteger(state, 2);
auto param_str = CheckStringSafe(state, 3, &param_length);

The implementation enforces a strict safety limit: the format string cannot exceed 37 characters. This ensures the total argument count stays within the fixed 40-slot buffer (3 header slots + 37 payload slots). If param_length >= 37, the function raises a Lua error immediately.

Buffer Preparation and Format String Processing

The module allocates a fixed-size array int64_t tse_args[40] on the stack and populates the first three indices with header metadata:

• tse_args[0] = Event hash identifier
• tse_args[1] = Sender player ID from Self::GetPlayer().GetId()
• tse_args[2] = Target player bitmask

int64_t tse_args[40];
tse_args[0] = hash;
tse_args[1] = Self::GetPlayer().GetId();
tse_args[2] = bits;

The function then iterates through the format string to convert Lua arguments into raw 64-bit integers. Each character in the format string dictates the conversion type:

• i – Integer: Cast to int64_t
• f – Float: Reinterpret-cast to int64_t
• l – Long (64-bit): Stored directly
• h – Hash (32-bit): Reinterpret-cast to int64_t

The loop reads corresponding Lua arguments starting at stack index 4 and packs them into tse_args[3 + i]:

for (int i = 0; i < param_length; ++i) {
    switch (param_str[i]) {
        case 'i':
            int as_int = luaL_checkinteger(state, 4 + i);
            tse_args[3 + i] = *(int64_t*)&as_int;
            break;
        case 'f':
            float as_float = luaL_checknumber(state, 4 + i);
            tse_args[3 + i] = *(int64_t*)&as_float;
            break;
        // ... cases for 'l' and 'h' follow similar patterns
    }
}

Native Event Transmission

Once the buffer is fully populated, the module invokes the native GTA V function SCRIPT::_SEND_TU_SCRIPT_EVENT_NEW. This call propagates the event to the game engine with the calculated argument count (3 + param_length), the player bitmask, and the original event hash.

SCRIPT::_SEND_TU_SCRIPT_EVENT_NEW(1, tse_args, 3 + param_length, bits, hash);

The function returns 0 to Lua, indicating completion without return values.

Helper Functions in the Network Library

Beyond event triggering, the Network module exposes additional utilities for script manipulation and session state queries.

force_script_host and force_script_on_player

The force_script_host function allows Lua scripts to seize control of a specific script thread, while force_script_on_player forces script execution on a targeted player mask. These functions interface with the underlying script management system in src/game/gta/Scripts.cpp.

is_session_started

This utility returns the current session state by dereferencing *Pointers.IsSessionStarted, enabling scripts to verify network connectivity before attempting event transmission.

Practical Usage Examples

Triggering a Custom Script Event from Lua

-- Send a script event with integer and float arguments
local eventHash = 0x12345678
local playerBits = -1  -- Broadcast to all players
local format = "if"    -- i = integer, f = float

network.trigger_script_event(eventHash, playerBits, format, 42, 3.14)

Forcing Script Execution on Specific Players

local scriptHash = 0xDEADBEEF
local targetPlayers = 0x2  -- Player index 2
network.force_script_on_player(scriptHash, targetPlayers)

Checking Session Status

if network.is_session_started() then
    print("Session active - safe to transmit events")
else
    print("No active session")
end

Key Source Files

The network scripting implementation spans several critical files in the YimMenuV2 codebase:

• src/game/scripting/libraries/Network.cpp – Implements trigger_script_event, force_script_host, force_script_on_player, and is_session_started
• src/game/gta/Scripts.cpp – Provides FindScriptThread and ForceScriptHost utilities used by network helpers
• src/game/backend/Self.cpp – Retrieves the local player object for sender ID population
• src/core/scripting/LuaLibrary.hpp – Base class handling registration of network functions to the global Lua table

Summary

• YimMenuV2 exposes scripted game events through the network.trigger_script_event Lua binding implemented in Network.cpp.
• The module validates a maximum of 37 payload arguments to prevent buffer overflows in the fixed 40-slot array.
• Format specifiers (i, f, l, h) control how Lua values are reinterpret-cast and packed into 64-bit integer slots.
• Events dispatch through the native SCRIPT::_SEND_TU_SCRIPT_EVENT_NEW function after populating headers with the event hash, sender ID, and player bitmask.
• Additional utilities like force_script_host and is_session_started provide comprehensive control over GTA V's network scripting environment.

Frequently Asked Questions

What is the maximum number of arguments allowed in trigger_script_event?

The function accepts up to 37 additional arguments beyond the three header values. This limitation exists because the internal tse_args buffer holds exactly 40 slots, with indices 0-2 reserved for the event hash, sender ID, and player bitmask. Exceeding this limit triggers a Lua error.

How does YimMenuV2 convert Lua types to GTA V script event arguments?

The format string parameter defines the conversion strategy. Integers (i) and longs (l) cast directly to int64_t, while floats (f) and hashes (h) use reinterpret-cast to preserve bit patterns during the 64-bit packing process. This ensures compatibility with the game's native expectations regardless of Lua's dynamic typing.

Can script events target specific players or only broadcast to everyone?

The bits parameter accepts a player mask allowing precise targeting. Passing -1 broadcasts to all players, while specific bitmasks target individual player indices. This mechanism integrates directly with GTA V's native networking layer through the _SEND_TU_SCRIPT_EVENT_NEW call.

Where does the Network library register its functions for Lua access?

All network functions register during library initialization through the Register method defined in LuaLibrary.hpp. This binds trigger_script_event, force_script_host, force_script_on_player, and is_session_started to the global network table available to YimMenuV2 Lua scripts.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}