# TriggerVolume An invisible 3D shape that detects when objects enter or exit a given region of space. ``` @MainActor @preconcurrency class TriggerVolume ``` ## Overview A trigger volume is an entity that can participate in collisions because it has a [`CollisionComponent`](/documentation/RealityKit/CollisionComponent). You use a trigger volume as a sensor that indicates when another collision-capable entity, like a [`ModelEntity`](/documentation/RealityKit/ModelEntity), enters the region of space occupied by the trigger volume. You can use the generated [`CollisionEvents`](/documentation/RealityKit/CollisionEvents) between the trigger volume and the other entity to trigger an action, like indicating to the user that a projectile hit its target.  The trigger volume itself is very simple. It lacks any physical appearance, and doesn’t participate in physics simulations. This makes it very efficient for tasks that require only collision detection. ## Topics ### Creating a trigger volume [`init()`](/documentation/RealityKit/TriggerVolume/init()) Creates a trigger volume. [`init(shape:filter:)`](/documentation/RealityKit/TriggerVolume/init(shape:filter:)) Creates a trigger volume with the given shape and collision filter. [`init(shapes:filter:)`](/documentation/RealityKit/TriggerVolume/init(shapes:filter:)) Creates a trigger volume with the given composite shape and collision filter. ### Accessing the collision component [`collision`](/documentation/RealityKit/HasCollision/collision) The collision component that gives the entity the ability to participate in collision simulations. ### Detecting collisions [Configuring Collision in RealityKit](/documentation/RealityKit/configuring-collision-in-realitykit) Use collision groups and collision filters to control which objects collide. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)