using UnityEngine;
using System.Collections.Generic;

// Allows particle effects to follow a GameObject without being parented to that GameObject.
// This way, destroying the track target doesn't also destroy the effect.

public class EffectTracker : MonoBehaviour {

    // A list of effect roots and their corresponding targets
    private static List<(GameObject effect, GameObject target)> trackers = new List<(GameObject, GameObject)> ();

    // Add an effect to the list
    public static void Track (GameObject effect, GameObject target) {
        trackers.Add ((effect, target));
    }

    // Update all tracked effects
    void Update () {

        // Loop backwards through every tracked effect
        for (int i = trackers.Count - 1; i >= 0; i--) {
            var (effect, target) = trackers[i];

            // If either the effect or the target has been destroyed...
            if (effect == null || target == null) {
                // Stop tracking this effect
                trackers.RemoveAt (i);
            }

            // Otherwise...
            else {
                // Change the world position of the effect
                effect.transform.position = target.transform.position;
            }
        }
    }

}