Events System

HELIX has a built-in event system that lets different parts of your code communicate without tight coupling. Events work across client and server, so a server-side script can fire an event that a client catches (and vice versa).

In Blueprints, you use UE5's native Event Dispatchers and Custom Events — the standard Unreal approach. In Lua, HELIX provides a custom event API (global functions like RegisterServerEvent, TriggerClientEvent, etc.) that wraps native C++/Blueprint functionality into a simple scripting interface. JavaScript event support via HelixJS is currently in development.

Registering Events

Blueprint

Blueprint— Registering an Event DispatcherScroll to zoom · Drag to pan · Drag nodes to move

Lua

-- Register a server-side event handler
RegisterServerEvent("PlayerScored", function(controller, playerId, points)
    -- controller is the triggering player (passed automatically)
    print("Player " .. playerId .. " scored " .. points .. " points!")
end)

-- Register a client-side event handler
RegisterClientEvent("UpdateScoreUI", function(playerId, points)
    print("UI update: " .. playerId .. " now has " .. points)
end)

JavaScript

Coming Soon

The HelixJS event API (Helix.on, Helix.emit) is currently in development. JavaScript event support will be available in a future update. For now, use Lua or Blueprints for event-driven communication.

Triggering Events

Blueprint

Blueprint— Calling an Event DispatcherScroll to zoom · Drag to pan · Drag nodes to move

For cross-network events, use the scripting layer (Lua/JS).

Lua

-- Client → Server: trigger a server event from the client
TriggerServerEvent("PlayerScored", "player_42", 100)

-- Server → Specific Client: send to one player
TriggerClientEvent(controller, "UpdateScoreUI", "player_42", 100)

-- Server → All Clients: broadcast to everyone
BroadcastEvent("UpdateScoreUI", "player_42", 100)

JavaScript

Coming Soon

JavaScript event triggering via HelixJS is in development.

Built-in Game Events

HELIX fires these events automatically. Subscribe to them to react to core game moments:

Event	Context	Description
HEvent:PlayerReady	Server	A player has loaded and is ready
HEvent:PlayerUnloaded	Server	A player disconnects
HEvent:CharacterSpawned	Server	A character has been spawned

note

The built-in event names and signatures may evolve during the Closed Alpha. Check the reference documentation for the latest list.

Custom Events

Define your own events for game-specific logic. Pick a name and go:

Blueprint

Blueprint— Custom Event DispatcherScroll to zoom · Drag to pan · Drag nodes to move

Lua

-- Start a zombie wave and tell all clients about it
function M:StartWave(waveNumber)
    local count = waveNumber * 10
    self:SpawnZombies(count)
    BroadcastEvent("ZombieWaveStarted", waveNumber, count)
end

JavaScript

Coming Soon

JavaScript custom events via HelixJS are in development.

Cross-Package Events

Events are great for cross-package communication. Use local events to communicate between packages on the same side (client-to-client or server-to-server):

-- Package A (server): notify other server packages
TriggerLocalServerEvent("InventoryUpdated", playerId, inventoryData)

-- Package B (server): listen for cross-package events
RegisterServerEvent("InventoryUpdated", function(controller, playerId, data)
    -- Update your systems
end)

Lua Event API Summary

These are global functions available in Lua scripts. They wrap HELIX's native C++ event system into a simple scripting interface.

Function	Direction	Description
RegisterServerEvent(name, cb)	Server	Register a server event handler
RegisterClientEvent(name, cb)	Client	Register a client event handler
TriggerServerEvent(name, ...)	Client → Server	Trigger a server event from the client
TriggerClientEvent(ctrl, name, ...)	Server → Client	Send event to a specific client
TriggerLocalServerEvent(name, ...)	Server → Server	Cross-package server event
TriggerLocalClientEvent(name, ...)	Client → Client	Cross-package client event
BroadcastEvent(name, ...)	Server → All Clients	Send event to all connected clients

tip

When triggering a server event from a client, the triggering player's controller is automatically passed as the first argument to the server handler (similar to FiveM's source). You don't need to send it manually.

The event system serializes arguments automatically across the network. Stick to primitive types (strings, numbers, booleans) and simple tables/objects for the smoothest experience.