Triggers

Triggers are objects in the world that can trigger a certain behavior. This can be to open a window, open a door, etc. A simple example of a trigger is a treasure chest. When the player clicks it the treasure chest becomes activated, the user can loot items, and when clicked again the trigger is un-used and the treasure chest closes.

Input handlers

Input handlers are responsible for handling the input to use / un-use the trigger. This can be by the click of a mouse, tap of a finger, or the press of a (controller) button. The default TriggerInputHandler handles all 3 of these use cases.

ITriggerInputHandler

The ITriggerInputHandler interface can be implemented into a custom component to handle the input for the trigger.

Attach the following script to your trigger to handle it's input. You can also select it through the editor.

using Devdog.General2;

public class MyTriggerInputHandler : TriggerInputHandlerBase
{
    public override TriggerActionInfo actionInfo
    {
        get
        {
            return new TriggerActionInfo()
            {
                actionName = triggerKeyCode.ToString()
            };
        }
    }

    [SerializeField]
    private bool _triggerMouseClick = true;
    public virtual bool triggerMouseClick
    {
        get { return _triggerMouseClick; }
    }

    public override bool AreKeysDown()
    {
        if (_triggerKeyCode == KeyCode.None)
        {
            return false;
        }

        return Input.GetKeyDown(_triggerKeyCode);
    }

    public override void OnPointerClick(PointerEventData eventData)
    {
        base.OnPointerClick(eventData);
        if (_triggerMouseClick)
        {
            Use();
        }
    }

    public override string ToString()
    {
        return triggerKeyCode.ToString();
    }
}

Range handlers

A range handler is responsible for defining when the character that intends to use the trigger is in range or not. This can be a simple Vector3.Distance check, a Physics trigger, or something specific for your game type.

Trigger Range Handler

The default trigger range handler uses Unity's built-in physics system and creates a sphere trigger. This TriggerRangeHandler can only be used in combination with the 3D physics system.

Trigger Range Handler 2D

When you're building a 2D game, and wish to use the built-in range handler, you have to use teh TriggerRangeHandler2D; This is because the regular range handler uses a 3D sphere trigger, which is not compatible with 2D physics.

Trigger callbacks

The ITriggerCallbacks interface defines a component that can receive callbacks when the trigger is used or un-used.

Attach the script to your trigger so it will receive callbacks.

using Devdog.General2;

public sealed class MyTriggerCallbacks : MonoBehaviour, ITriggerCallbacks
{
    public void OnTriggerUsed(Character character, TriggerEventData eventData)
    {
        // Do something here, like playing an animation on your character.
    }

    public void OnTriggerUnUsed(Character character, TriggerEventData eventData)
    {
        // Do something here...
    }
}