Different "Use" function for different items.

Unity Engine
1

I currently have a setup where I can look at items and pick them up (destroy them for now ?) via this script: Pickup Items Script

using UnityEngine;
using System.Collections;

public class PickupItems : MonoBehaviour {

    public float interactDistance = 3;
    int pickupsLayerMask;
    int screenX;
    int screenY;


    // Use this for initialization
    void Start () {
        screenX = Screen.width / 2;
        screenY = Screen.height / 2;

        pickupsLayerMask = LayerMask.GetMask ("Pickups");

    }
   
    // Update is called once per frame
    void Update () {
   
        RaycastHit hit;
        Ray ray = Camera.main.ScreenPointToRay(new Vector3(screenX, screenY));

        if (Physics.Raycast (ray, out hit, interactDistance, pickupsLayerMask )) {

            Debug.Log("Pickup!" + Time.time);
            Destroy(hit.transform.gameObject);
        }

    }
}

And instead of just destroying the objects, which currently is just a testing mechanism kinda thing, I would like to make it so I call a function specific to the type of item that it is, so perhaps like if it was a door it wouldn’t actually destroy it would just swing open (probably gonna change the script to “interactblahblahblah”)

This is kind of a for instance, as it also interests me to make it so that like when an item is in my inventory and I use it, then it will also run a specific function for that kind of item.

I have a feeling I will need to use inheritance but I don’t have much of an idea of how that can be done in unity.

2

This is the perfect use case for an interface. Create an interface like IUseable with a Use() method. Implement it on the appropriate MonoBehaviours (like a DoorHandler script) and then you can interact with any object generically.

3

Would I not have to have the script file name to call it? I am under the impression that I would have to make a different case for each component.
Such as getting the DoorHandler script and then calling it. and for each different type of item I would need to get a reference to that script

4

Nope, you can grab components by interface with the non-generic GetComponent:

IUseable useable = (IUseable)gameObject.GetComponent(typeof(IUseable));

If you’d prefer to use the generic type, you can use an abstract base class implementing your interface instead. Here’s an example.

5

Im getting an exception on this line:

((Interactable)hit.transform.gameObject.GetComponent(typeof(Interactable))).Use();

NullReferenceException: Object reference not set to an instance of an object
Interact.interaction (RaycastHit hit) (at Assets/Scripts/Player/Interactions/Interact.cs:74)
Interact.Update () (at Assets/Scripts/Player/Interactions/Interact.cs:58)

Any ideas? Should I make it an actual object like in your code?

6

Consider using Unity’s Event System. It’s built on C# interfaces, but it’s easier to use because you don’t need to get components.

Define an event message like this:

// IUseEvent.cs:
public interface IUseEvent : IEventSystemHandler {
    void Use();
}

Then add scripts that implement IUseEvent to your items:

// DestroyOnUse.cs:
public class DestroyOnUse : MonoBehaviour, IUseEvent {
    public void Use() {
        Destroy(this.gameObject);
    }
}

// AnimateOnUse.cs:
public class AnimateOnUse : MonoBehaviour, IUseEvent {
    public string animatorState;

    public void Use() {
        GetComponent<Animator>().Play(animatorState);
    }
}

etc.

Finally, in your PickupItems script, instead of Destroy(), execute the event:

ExecuteEvents.Execute<IUseEvent>(hit.gameObject, null, (x,y)=>x.Use());