Trigger Sensors

Trigger sensor component and sensor types — condition evaluation objects for physics, interact, and record-based world trigger activation.

Tags:

TriggerSensorComponent is the condition container of the World Trigger system. It owns arrays of TriggerSensorType objects that define evaluation logic — collisions, interactions, record checks. When conditions pass, it fires WorldTriggerRequestBus::Trigger on the same entity.

For usage guides and setup examples, see The Basics: GS_Interaction.

Container Component

TriggerSensorComponent

Trigger Sensor component in the O3DE Inspector

Owns and evaluates all sensor type objects. Not subclassed — extended by adding TriggerSensorType objects to its arrays.

Bus: TriggerSensorRequestBus (ById, Single)

Field	Type	Description
`andConditions`	`vector<TriggerSensorType*>`	All types must pass for the trigger to fire.
`orConditions`	`vector<TriggerSensorType*>`	Any type passing is sufficient to fire.

Method	Returns	Description
`DoAction`	`void`	Evaluates all conditions. On pass, fires `WorldTriggerRequestBus::Trigger` and `TriggerSensorNotificationBus::OnTriggered`.
`DoResetAction`	`void`	Evaluates reset conditions and fires reset if they pass.

On Activate, automatically activates a PhysicsTriggerComponent on the entity if any sensor type returns true from NeedsPhysicsTrigger().

Base Type Class

TriggerSensorType

Abstract base for all sensor evaluation logic. Not a component — reflected manually in GS_InteractionSystemComponent::Reflect(). Subclass this to add new condition types.

Virtual	Returns	Description
`Activate(entityId)`	`void`	Called when the owning component activates. Connect to buses here.
`Deactivate()`	`void`	Called when the owning component deactivates. Disconnect from buses here.
`EvaluateAction()`	`bool`	Returns `true` if the condition is currently satisfied.
`EvaluateResetAction()`	`bool`	Returns `true` if the reset condition is satisfied. Returns `true` by default.
`NeedsPhysicsTrigger()`	`bool`	Return `true` to signal that a `PhysicsTriggerComponent` should be activated. Returns `false` by default.
`OnTriggerEnter(entity)`	`void`	Called by the physics trigger when an entity enters the volume.
`OnTriggerExit(entity)`	`void`	Called by the physics trigger when an entity exits the volume.

Stores m_ownerEntityId for calling back to TriggerSensorRequestBus::DoAction() or DoResetAction() from event-driven types.

Built-in Sensor Types

SensorType_Collider

Physics overlap sensor. Returns NeedsPhysicsTrigger() = true, causing the owning component to activate a PhysicsTriggerComponent.

OnTriggerEnter stores the entering entity.
OnTriggerExit clears the stored entity.
EvaluateAction() returns true while a valid entity is present.
EvaluateResetAction() returns true when no entity is present.

SensorType_Record

Fires when a named save record changes to a configured value. Extends RecordKeeperNotificationBus — connects on Activate and fires DoAction automatically when the matching record changes.

EvaluateAction() calls GetRecord and compares against recordValue.

→ Record Sensor Type Reference

Field	Description
`recordName`	Name of the record to watch.
`recordValue`	Value the record must reach to fire.

SensorType_Interact

Fires when any unit interacts with this entity via the targeting system. Extends InteractTriggerSensorRequestBus.

On interact: stores lastCaller and calls DoAction.
EvaluateAction() returns true while lastCaller is a valid entity.

SensorType_PlayerInteract

Player-only variant of SensorType_Interact. Extends SensorType_Interact and adds a tag check — lastCaller must have the "Player" tag for the condition to pass.

Extension Guide

To create a custom sensor type:

Create a class extending TriggerSensorType.
Override EvaluateAction() to define when your condition is satisfied.
Override Activate(entityId) / Deactivate() to connect and disconnect from any buses.
For event-driven evaluation, listen on a bus and call TriggerSensorRequestBus::DoAction(m_ownerEntityId) when the event fires — the component will run the full evaluation pipeline.
Return true from NeedsPhysicsTrigger() if your type needs a physics volume.
Reflect the class in GS_InteractionSystemComponent::Reflect() — types are not components and are not registered via CreateDescriptor().

Get GS_Interaction

GS_Interaction — Explore this gem on the product page and add it to your project.