OnTrigger

OnTrigger is a common term in game development, particularly within physics engines, referring to an event that occurs when two colliders intersect and at least one of them is marked as a trigger. A collider is a shape that defines the physical boundaries of a game object. When one collider enters the volume of another, and that other collider is set as a trigger, an OnTriggerEnter event is usually invoked. Similarly, when a trigger collider exits another, an OnTriggerExit event is fired, and while a trigger collider remains within another, an OnTriggerStay event is continuously triggered.

Triggers are distinct from standard colliders because they do not produce physical responses like collisions. Instead, they are primarily used for detecting overlap and initiating actions. For example, a trigger could be used to detect when a player character enters a power-up zone, picks up an item, or crosses a checkpoint. Game developers implement these events in their scripts to define what happens when such interactions occur. The specific implementation and naming conventions for these trigger events can vary slightly between different game engines and physics frameworks, but the core concept of detecting non-physical overlap remains consistent.