Proximity: reacting without a prompt

A Proximity block (FMovaIxProximity) lets an IC fire interactions from an overlap alone, no interaction point, no prompt, no player input at all. A light that turns on as you approach, a fan that spins only while you stand near it, a door that hisses open when you're close: all three are Proximity, not the tagged interaction system on the component itself.

Save the real screenshot as: shot-editor-viewport-proximity-lamp.png

Shape: where the volume comes from

Shape	What it does
None	No auto-volume. Only interactor-driven proximity (if any) applies.
Box	The IC auto-creates a hidden box collision on this actor, sized by BoxExtent and placed at RelativeLocation / RelativeRotation.
Sphere	Same, but a sphere sized by SphereRadius (rotation is ignored: a sphere has none).
Volume	Binds to every level volume actor tagged VolumeTag instead of auto-creating anything: hand-place an irregular trigger in the level and tag it.

Box and Sphere are the fast path: no separate trigger actor to place, the IC owns the collision itself. Volume is for a trigger the two primitives can't express (an L-shape room, a volume that follows a corridor).

Only an actor carrying a UMovaIxInteractorComponent (the player pawn, by convention) triggers a Proximity volume. Static geometry and non-interactor pawns overlap it with no effect.

Enter / Leave: the same tag grammar

EnterTags and LeaveTags are each a list of ordinary interaction tags, run the moment the interactor enters or leaves range:

EnterTags: !On @Lamp
LeaveTags: !Off @Lamp

These are the same tokens used everywhere else in the plugin (flow prefix, @/%/# target, optional ? gate), so Tag Grammar Reference covers them in full. A Proximity Enter tag can target an external actor (%Fan^), gate itself (?@Power:On), or fire a Group directly, same as a component tag.

        graph LR
    A[Player enters volume] -->|EnterTags| B["!On @Lamp"]
    C[Player leaves volume] -->|LeaveTags| D["!Off @Lamp"]
    B --> E[Lamp Group: On]
    D --> F[Lamp Group: Off]
    

Use cases

Goal	Shape	Enter	Leave
Light that turns on as you approach	Sphere	!On @Lamp	!Off @Lamp
Fan spinning only while you stand near it	Sphere	!Spin @Blade	!Stop @Blade
Auto-door that opens on approach	Box in front of the door	!Open @Door	!Close @Door
Ambient trigger tied to a hand-placed volume	Volume, VolumeTag = "AmbientZone"	!Play @Speaker	!Stop @Speaker

In the "fan spinning while you stand near it" case, LeaveTags firing !Stop on exit makes the effect presence-driven instead of one-shot: the fan spins only while an interactor sits inside the sphere, with no group left running (and no wasted RampOutTime) once they walk away.

Proximity vs the player Interactor

Proximity and The player Interactor: setup and use solve different problems and commonly sit side by side on the same object:

• Proximity is passive: it needs no player input, only presence. Good for ambience and environmental reactions.

• The Interactor (UMovaIxInteractorComponent) is active: it finds the best interaction point in view and fires it on a button press. Good for doors, levers, and anything the player should choose to trigger instead of walk into.

A single IC can have both: a Proximity sphere that lights a room on approach, and an interaction point on the same mesh that the player presses to do something else entirely.

See also

• Tag Grammar Reference: full syntax for the Enter/Leave tag tokens.

• Gates: locks & conditions: gate a Proximity tag with ? the same way as any other target.

• The player Interactor: setup and use: the active, aim-and-press counterpart.

• Debug overlay & troubleshooting: mova.ix.Debug draws the Proximity volume live.

• FMovaIxProximity, EMovaIxProximityShape in the API reference.