Collision Events

Read collision and sensor events from the PhysicsEvents resource each frame.

PhysicsEvents Resource

import { defineSystem, addSystem, Res } from 'esengine';
import { PhysicsEvents } from 'esengine/physics';

addSystem(defineSystem(
    [Res(PhysicsEvents)],
    (events) => {
        for (const e of events.collisionEnters) {
            // e.entityA, e.entityB, e.normalX, e.normalY, e.contactX, e.contactY
        }
        for (const e of events.collisionExits) {
            // e.entityA, e.entityB
        }
        for (const e of events.sensorEnters) {
            // e.sensorEntity, e.visitorEntity
        }
        for (const e of events.sensorExits) {
            // e.sensorEntity, e.visitorEntity
        }
    }
));

Event Types

Collision Enter

Fired on the first frame two non-sensor colliders begin touching.

Field	Type	Description
entityA	Entity	First entity in the collision pair
entityB	Entity	Second entity in the collision pair
normalX	number	Collision normal X component
normalY	number	Collision normal Y component
contactX	number	Contact point X in world space
contactY	number	Contact point Y in world space

Collision Exit

Fired on the first frame two non-sensor colliders stop touching.

Field	Type	Description
entityA	Entity	First entity in the collision pair
entityB	Entity	Second entity in the collision pair

Sensor Enter

Fired when a non-sensor collider begins overlapping a sensor collider.

Field	Type	Description
sensorEntity	Entity	Entity with isSensor = true
visitorEntity	Entity	Entity that entered the sensor zone

Sensor Exit

Fired when a non-sensor collider stops overlapping a sensor collider.

Field	Type	Description
sensorEntity	Entity	Entity with isSensor = true
visitorEntity	Entity	Entity that left the sensor zone

Tip

Set isSensor = true on a collider to create a trigger zone that detects overlaps without physical response. See Colliders for details.

See Also

• Physics Overview — setup and configuration
• Colliders — collider shapes and sensor property
• API — runtime physics control