AStarMain Script

using UnityEngine;
using System.Collections;

public class AStarMain : MonoBehaviour {
    GameObject thisObject;
    PathfindingNode[,] nodes;

    public float lookInterval;
    public int lookDistance;
    public GameObject pathMarkerObj;
    public GameObject targetObj;
    public GameObject emptyPrefab;
    public Vector2 thisPosition;
    public Vector2 targetPosition;

    // Use this for initialization
    void Start () {
        thisObject = this.gameObject;
        thisPosition = new Vector2 (lookDistance / 2, lookDistance / 2);
        nodes = new PathfindingNode[lookDistance,lookDistance];
        if ((double)(lookDistance / 2) != (int)(lookDistance / 2))
        {
            lookDistance++;
        }
        setUpGrid ();
    }

    // Update is called once per frame
    void Update () {
        RaycastHit hit = new RaycastHit();
        Physics.Raycast(this.transform.position, Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, 1)), out hit);
        if (Input.GetMouseButtonDown(0))
        {
            targetObj.transform.position = new Vector3(hit.point.x,hit.point.y,hit.point.z);
            AStarHelper2.Calculate(nodes[(int)thisPosition.x,(int)thisPosition.y],nodes[(int)targetPosition.x,(int)targetPosition.y]);
            //Debug.Log(nodes[(int)thisPosition.x,(int)thisPosition.y].ConnectedNodes);
        }
    }

    void setUpGrid()//I create a grid of balls, if the raycast hits an object tagged with "world" it is walkable, otherwise
            //It is not.
    {
        GameObject grid;
        grid = Instantiate (emptyPrefab) as GameObject;
        grid.name = "grid";
        for (int x = 0; x < lookDistance; x++)
        {
            for (int y = 0; y < lookDistance; y++)
            {
                PathfindingNode p = ScriptableObject.CreateInstance<PathfindingNode>();
                Vector3 origin = new Vector3(x*lookInterval - lookDistance/2 + this.transform.position.x, this.transform.position.y, y*lookInterval  + this.transform.position.z - lookDistance/2);
                RaycastHit hit;
                Physics.Raycast(origin, Vector3.down, out hit);
                if (hit.collider.tag == "World")
                {
                    p.isWalkable = true;
                    GameObject g;
                    g = Instantiate(pathMarkerObj, origin, Quaternion.Euler(0,0,0)) as GameObject;
                    g.transform.parent = grid.transform;
                }
                else{
                    p.isWalkable = false;
                }
                nodes[x,y] = p;
            }
        }
        setUpNodeNeighbours ();
    }

    void setUpNodeNeighbours()//Where I tell which nodes are neighbours
    {
        for (int x = 0; x < lookDistance; x++)
        {
            for (int y = 0; y < lookDistance; y++)
            {
                ArrayList conNodes = new ArrayList();
                for (int a = -1; a < 1; a++)
                {
                    for (int b = -1; b < 1; b++)
                    {
                        try{
                            if(nodes[x + a, y + b].isWalkable)
                            {
                                conNodes.Add(nodes[x + a,y + b]);
                            }
                        }
                        catch(System.IndexOutOfRangeException e)
                        {
                        }
                    }
                }
                PathfindingNode[] connectedNodes = new PathfindingNode[conNodes.Count];
                for (int t = 0; t < conNodes.Count; t++)
                {
                    connectedNodes[t] = conNodes[t] as PathfindingNode;
                }
                nodes[x,y].ConnectedNodes = connectedNodes;

            }
        }
    }
}