CurrentNode

using UnityEngine;
using System.Collections;

public class CurrentNode : MonoBehaviour {

    public GameObject currentNode;

    // Use this for initialization
    void Start () {
        SetCurrentNode ();
    }

    void SetCurrentNode(){
        float shortestDistance = Mathf.Infinity;

        foreach (GameObject obj in GameObject.FindGameObjectsWithTag("Node")) {

            float dist = (obj.transform.position - transform.position).magnitude;
            if(dist < shortestDistance){
                shortestDistance = dist;
                currentNode = obj;
            }
        }
    }

    // Update is called once per frame
    void Update () {
        SetCurrentNode ();
    }
}