Draggable & Touch Objects

AchEngine provides three components for handling drag and touch interactions on 2D world objects.

Draggable

Attach the Draggable component to a MonoBehaviour to make it draggable with mouse or touch. If no Physics2DRaycaster is present, it is automatically added to the main camera.

using AchEngine.UI;

public class CardView : Draggable
{
    protected override void Start()
    {
        base.Start(); // auto-adds Physics2DRaycaster

        OnTouchDown += () => Debug.Log("Card picked up");
        OnTouching  += pos => Debug.Log($"Dragging at: {pos}");
        OnTouchUp   += hits => Debug.Log($"Dropped, hit {hits.Length} collider(s)");
    }
}

Events

Event	Signature	Description
OnTouchDown	Action	Fired when the pointer is pressed
OnTouching	Action<Vector3>	Fired while dragging (world position)
OnTouchUp	Action<Collider2D[]>	Fired on release, provides overlapping colliders

Properties

Property	Description
originalPos	World position at drag start (protected)

TouchableObject

Use this for objects that only need tap/click handling. Override OnTouched().

using AchEngine.UI;

public class EnemyObject : TouchableObject
{
    protected override void OnTouched()
    {
        Debug.Log("Enemy clicked");
    }
}

TouchableObject is detected by ObjectTouchManager. The scene must contain an ObjectTouchManager instance.

ObjectTouchManager

A singleton manager that exists once per scene. Each frame it detects left mouse button clicks, casts a 2D ray, and calls OnTouched() on any TouchableObject that is hit.

// Create an empty GameObject in the scene and attach ObjectTouchManager.
// No additional configuration is needed — it works automatically.

ObjectTouchManager inherits from MonoSingleton<ObjectTouchManager>, so duplicate instances are destroyed automatically.