Can I make a non UI gameObject draggable by implementing the IDragHandler interface?

Questions & Answers
1

I’ve been following an online tutorial where Ui Components are dragged by implementing the IDragHandler interface but when I tried to apply it to a non UI gameObject it’s not working, is there a way to make it work and any helpful tutorials on the subject?

3

You can.

You need to set up your eventsystem accordingly however.

To do this you need 2 things.

  1. An EventSystem
  2. A raycaster (A canvas uses a GraphicRaycaster, but you can also use Physics2DRaycaster or PhysicsRaycaster).

To make your object respond to events, simply add a PhysicsRaycaster to your camera, make sure you have an eventsystem somewhere in the scene, and that your MonoBehaviour implements IDragHandler (and make sure it has a collider obviously).

As for how to implement dragging, this is a simplified piece of code that allows you to drag in world x/z.

using UnityEngine;
using UnityEngine.EventSystems;

public class DragExample : MonoBehaviour, IDragHandler
{
    public void OnDrag(PointerEventData eventData)
    {
        // Vector3.up makes it move in the world x/z plane.
        Plane plane = new Plane(Vector3.up, transform.position);

        Ray ray = eventData.pressEventCamera.ScreenPointToRay(eventData.position);
        float distamce;
        if (plane.Raycast(ray, out distamce))
        {
            transform.position = ray.origin + ray.direction * distamce;
        }
    }
}
2

No, you’ll have to write up your own code structure.