Triggers

Beginner Designer

A trigger is a collision shape which detects when colliders enter it, it can be used to run an event when a player character enters a room for example.

Triggers in Stride's Bepu implementation fall into what is known as a special kind of Contact Event Handler.

The contact event handler is a class that receives collision data whenever the object it is associated with collides with the world.

If the contact event handler you bind to an object is set to NoContactResponse, it is a Trigger, the object will never prevent anything from passing through it, it will only receive collision events.

Here's a basic example of a component which acts as a trigger to display a message in the console:

using Stride.BepuPhysics;
using Stride.BepuPhysics.Definitions.Contacts;
using Stride.Engine;

public class Test : StartupScript, IContactEventHandler
{
    public bool NoContactResponse => true;

    void IContactEventHandler.OnStartedTouching<TManifold>(CollidableComponent eventSource, CollidableComponent other,
        ref TManifold contactManifold,
        bool flippedManifold,
        int workerIndex,
        BepuSimulation bepuSimulation)
    {
        Log.Warning("Entered!");
    }

    void IContactEventHandler.OnStoppedTouching<TManifold>(CollidableComponent eventSource, CollidableComponent other,
        ref TManifold contactManifold,
        bool flippedManifold,
        int workerIndex,
        BepuSimulation bepuSimulation)
    {
        Log.Warning("Exited!");
    }
}

For an example of how to use triggers, see the Script a trigger tutorial.

Table of Contents

Triggers

See also