trigger_device & hud_message_device: Indentation Matters on the Pirate Lagoon

Overview

Verse is an indentation-sensitive language: the indent level of a line determines which block it belongs to. Get it wrong and your if body runs unconditionally, your for loop exits early, or your event handler never fires. Unlike curly-brace languages, there are no {} to save you — the whitespace is the grammar.

The two devices we use to make this concrete are:

• trigger_device — a pressure plate or invisible zone that fires TriggeredEvent when a player steps on it. You can also call Trigger() in code, set limits with SetMaxTriggerCount, and add delays with SetResetDelay.
• hud_message_device — shows a custom message on one or all players' screens. Call Show(Agent, Message) for a targeted pop-up, SetText to change the message, and ClearAllMessages to wipe the slate.

When to reach for these together: Any time you need a spatial event (player walks somewhere) to communicate feedback ("You found the treasure!"). Classic uses: checkpoint announcements, puzzle hints, countdown warnings, and — as we'll build below — a pirate lagoon discovery sequence.

API Reference

trigger_device

Used to relay events to other linked devices.

Full public surface, resolved verbatim from the live Epic digest (Fortnite.digest.verse). Inherited members are merged from trigger_base_device.

trigger_device<public> := class<concrete><final>(trigger_base_device):

Events (subscribe a handler to react):

Methods (call these to make the device act):

player

Full public surface, resolved verbatim from the live Epic digest (Verse.digest.verse). Inherited members are merged from agent.

player<native><public> := class<unique><persistent><module_scoped_var_weak_map_key><epic_internal>(agent):

hud_message_device

Used to show custom HUD messages to one or more agents.

Full public surface, resolved verbatim from the live Epic digest (Fortnite.digest.verse).

hud_message_device<public> := class<concrete><final>(creative_device_base):

Events (subscribe a handler to react):

Methods (call these to make the device act):

Walkthrough

Scene: The Pirate Lagoon Discovery

Your cel-shaded island has three zones:

1. The Dock — players start here.
2. The Cove — a hidden inlet halfway along the shore.
3. The Clifftop — a treasure chest sits at the top.

Three trigger_device pressure plates mark each zone. When a player steps on one, a hud_message_device flashes the zone name. The Clifftop trigger is one-shot (fires once per player session) and uses a reset delay so it can't be spammed. The Cove trigger broadcasts to all players.

This example demonstrates:

• Subscribing to TriggeredEvent (a listenable(?agent)) and unwrapping the optional agent.
• Calling Show(Agent, Message) for targeted messages and Show(Message) for global ones.
• Using SetMaxTriggerCount, SetResetDelay, and SetText at startup.
• How indentation inside if, OnBegin, and handler methods controls exactly what runs.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

# Localized message helpers — message params MUST be declared like this.
DockMsg<localizes>(S : string) : message = "{S}"
CoveMsg<localizes>(S : string) : message = "{S}"
CliffMsg<localizes>(S : string) : message = "{S}"

pirate_lagoon_discovery := class(creative_device):

    # ── Placed devices — wire these up in the UEFN editor ──
    @editable
    DockTrigger : trigger_device = trigger_device{}

    @editable
    CoveTrigger : trigger_device = trigger_device{}

    @editable
    ClifftopTrigger : trigger_device = trigger_device{}

    @editable
    HUD : hud_message_device = hud_message_device{}

    # ── Lifecycle ──
    OnBegin<override>()<suspends> : void =
        # Configure the Clifftop trigger: one shot, 2-second reset.
        # INDENTATION NOTE: these three calls are all inside OnBegin's block.
        ClifftopTrigger.SetMaxTriggerCount(1)
        ClifftopTrigger.SetResetDelay(2.0)

        # Pre-load the HUD device's default text (shows for 4 seconds).
        HUD.SetDisplayTime(4.0)
        HUD.SetText(DockMsg("Welcome to the Pirate Lagoon!"))

        # Subscribe handlers — each is a method defined below.
        DockTrigger.TriggeredEvent.Subscribe(OnDockTriggered)
        CoveTrigger.TriggeredEvent.Subscribe(OnCoveTriggered)
        ClifftopTrigger.TriggeredEvent.Subscribe(OnClifftopTriggered)

    # ── Event handlers ──
    # TriggeredEvent sends ?agent — we MUST unwrap with if (A := Agent?).

    OnDockTriggered(Agent : ?agent) : void =
        # INDENTATION NOTE: the if-body is indented one level deeper.
        if (A := Agent?):
            # Only the triggering player sees this message.
            HUD.Show(A, DockMsg("⚓ You're on the Dock."))
        # This line is OUTSIDE the if — it always runs, even if no agent.
        # (Useful for debug; remove in production.)

    OnCoveTriggered(Agent : ?agent) : void =
        # Broadcast to ALL players — no agent needed for Show().
        # INDENTATION NOTE: both lines below are siblings in this method's block.
        HUD.ClearAllMessages()
        HUD.Show(CoveMsg("🏴‍☠️ Someone found the Secret Cove!"))

    OnClifftopTriggered(Agent : ?agent) : void =
        if (A := Agent?):
            # Targeted message: only the discoverer sees this.
            HUD.Show(A, CliffMsg("💀 TREASURE FOUND! You reached the Clifftop!"), ?DisplayTime := 6.0)
            # Re-enable the trigger so the NEXT player can also trigger it once.
            # INDENTATION NOTE: this is still inside the if-block — it only
            # runs when a real agent triggered it, not a code-only trigger.
            ClifftopTrigger.Enable()

Line-by-line highlights

Common patterns

Pattern 1 — Checking trigger budget before firing (GetTriggerCountRemaining)

The lagoon's cannon trigger should only fire while ammo remains. Use GetTriggerCountRemaining to gate a HUD warning.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

CannonWarning<localizes>(S : string) : message = "{S}"

cannon_ammo_checker := class(creative_device):

    @editable
    CannonTrigger : trigger_device = trigger_device{}

    @editable
    HUD : hud_message_device = hud_message_device{}

    OnBegin<override>()<suspends> : void =
        # Give the cannon 5 shots total.
        CannonTrigger.SetMaxTriggerCount(5)
        CannonTrigger.TriggeredEvent.Subscribe(OnCannonFired)

    OnCannonFired(Agent : ?agent) : void =
        # GetTriggerCountRemaining tells us shots left AFTER this one.
        Remaining := CannonTrigger.GetTriggerCountRemaining()
        if (Remaining = 1):
            # INDENTATION: only this message shows when exactly 1 shot remains.
            HUD.Show(CannonWarning("⚠️ Last cannonball!"))
        if (Remaining = 0):
            # INDENTATION: this block is a SEPARATE if — both can't be true at once,
            # but they are evaluated independently because they are sibling blocks.
            HUD.Show(CannonWarning("💥 Cannon is empty!"))
            CannonTrigger.Disable()

Pattern 2 — Transmit delay for a dramatic reveal (SetTransmitDelay + code-triggered Trigger)

The pirate ship's foghorn trigger fires from code after a 3-second transmit delay, then shows a message.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

FogMsg<localizes>(S : string) : message = "{S}"

foghorn_reveal := class(creative_device):

    @editable
    FoghornTrigger : trigger_device = trigger_device{}

    @editable
    HUD : hud_message_device = hud_message_device{}

    OnBegin<override>()<suspends> : void =
        # The trigger will wait 3 s before notifying linked devices.
        FoghornTrigger.SetTransmitDelay(3.0)
        FoghornTrigger.TriggeredEvent.Subscribe(OnFoghorn)

        # Fire the trigger from code (no agent) after setup.
        # INDENTATION: this call is in OnBegin's block, so it runs at game start.
        FoghornTrigger.Trigger()

    OnFoghorn(Agent : ?agent) : void =
        # Agent is false/none here because we called Trigger() with no agent.
        # INDENTATION: the if runs only when a real player triggered it.
        if (A := Agent?):
            HUD.Show(A, FogMsg("🚢 A ship emerges from the fog!"))
        # This always runs — even for code-triggered events.
        HUD.Show(FogMsg("🌫️ The foghorn echoes across the lagoon..."))

Pattern 3 — Dynamic text swap with SetText + Hide

The lagoon's tide warning cycles between two messages. SetText changes what the device will show next; Hide clears the current message before swapping.

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }

TideMsg<localizes>(S : string) : message = "{S}"

tide_warning_cycle := class(creative_device):

    @editable
    TideTrigger : trigger_device = trigger_device{}

    @editable
    HUD : hud_message_device = hud_message_device{}

    # Track which message to show next.
    var ShowingHighTide : logic = false

    OnBegin<override>()<suspends> : void =
        HUD.SetDisplayTime(0.0)  # Persistent until hidden.
        TideTrigger.TriggeredEvent.Subscribe(OnTideToggle)

    OnTideToggle(Agent : ?agent) : void =
        # Hide the current message before swapping text.
        HUD.Hide()

        if (ShowingHighTide?):
            # INDENTATION: this block runs when ShowingHighTide is true.
            HUD.SetText(TideMsg("🌊 Low tide — safe to cross the sandbar!"))
            set ShowingHighTide = false
        else:
            # INDENTATION: this else-block is at the SAME level as the if.
            HUD.SetText(TideMsg("🌊 HIGH TIDE — stay off the rocks!"))
            set ShowingHighTide = true

        # Show the newly set text — runs regardless of which branch was taken.
        # INDENTATION: back at method level, outside both if and else.
        HUD.Show()

Gotchas

1. TriggeredEvent sends ?agent, not agent

The handler signature is (Agent : ?agent) : void. If you write (Agent : agent) the subscription will fail to compile. Always unwrap:

if (A := Agent?):
    HUD.Show(A, MyMsg("Hello!"))

Code-triggered calls (Trigger() with no argument) send false for the agent, so the if body is skipped — which is usually what you want.

2. message is NOT a string

HUD.Show, HUD.SetText, and the Show(Agent, Message, ...) overload all take message, not string. You must declare a <localizes> helper:

MyLabel<localizes>(S : string) : message = "{S}"
# Then:
HUD.SetText(MyLabel("Ahoy!"))

There is no StringToMessage function in Verse.

3. SetMaxTriggerCount clamps to [0, 20]

Passing 21 silently becomes 20. Pass 0 for unlimited. Check the remaining count with GetTriggerCountRemaining() — it returns 0 when the limit is unlimited (not when zero shots remain), so don't use it as a "shots left" counter when the limit is 0.

4. int and float do not auto-convert

SetResetDelay takes a float. Writing SetResetDelay(2) will not compile. Write SetResetDelay(2.0).

5. Indentation is the block delimiter — use exactly 4 spaces

Verse uses 4-space indentation. Mixing tabs and spaces, or using 2 spaces, produces confusing parse errors. The most dangerous mistake is accidentally dedenting a line out of an if block:

# WRONG — the HUD.Show runs unconditionally!
if (A := Agent?):
    ClifftopTrigger.Enable()
HUD.Show(A, CliffMsg("Found it!"))  # A is not in scope here!

# CORRECT — both lines are inside the if.
if (A := Agent?):
    ClifftopTrigger.Enable()
    HUD.Show(A, CliffMsg("Found it!"))

6. Disable() vs SetMaxTriggerCount(1)

Disable() prevents the trigger from firing at all (even from code). SetMaxTriggerCount(1) lets it fire once then stop — but Enable() re-arms it. Choose based on whether you want the trigger permanently off or just limited.