Unity C#. How do I link instantiated objects to a pathfinding script and how do I make a gameobject move to a list of nodes?

Question

I'm using Unity and C# and I am fairly new to both.

I have a class called Pathfinding attached to a empty gameobject. It requires a link to a start gameobject and an end gameobject and makes a list of nodes between the two in the shortest path. (A*).

What I need help with is:

How do I instantiate my enemy gameobject from a prefab and link it to this script (usually done by dragging the gameobject onto the respective tile in the editor).
How can I make a gameobject move by following the list created by the pathfinding algorithm (maybe takes the first one of the list, moves, then recalculates)? More info: My board is divided into many small cubes, the algorithm uses these to create a path. The path (list of these nodes) is stored. I want multiple enemies to

Thank you very much. Ask me if its not clear enough and I'll try to provide screenshots or info. :)

Lotan Lotan · Accepted Answer · 2018-11-23T14:28:04

1. Instantiate enemy and add it to a list (which is in your script):

using UnityEngine;

    public class Controller: MonoBehaviour
    {
        GameObject enemyPrefab;

        List<GameObject> enemiesList = new List<GameObject>();

        void Start()
        {
          GameObject enemy = Instantiate(enemiePrefab, transform.position, transform.rotation);
          enemiesList.Add(enemy);
        }
    }

2. Make the object move on your pathfinding:

There are many ways to do that, but I suggest you to store in a List, array or whatever you want, the different waypoints that you have. Then make your enemies follow one waypoint after another.

So now your main script should look like:

using UnityEngine;

public class Controller : MonoBehaviour
{
    public GameObject enemyPrefab;

    private List<GameObject> enemiesList = new List<GameObject>();
    public List<GameObject> wayPoints = new List<GameObject>();

    void Start()
    {
      GameObject enemy = Instantiate(enemiePrefab, transform.position, transform.rotation);
      enemy.wayPoints = wayPoints;
      enemiesList.Add(enemy);
    }
}

And your enemy script should look like:

using UnityEngine;

    public class Enemy : MonoBehaviour
    {
       public List<GameObject> wayPoints = new List<GameObject>();

       public float speed;
       private Transform target;
       int waypointIndex = 0;

       private void Start()
       {
         target = List[waypointIndex].transform;
         waypointIndex++;
       }

        void Update()
        {
          // The step size is equal to speed times frame time.
          float step = speed * Time.deltaTime;

          // Move our position a step closer to the target.
          transform.position = Vector3.MoveTowards(transform.position, target.position, step);

          //If we arrive to the target, get the new target
          if(this.transform.position == target.position)
          {
            waypointIndex++;
            //if it is the last element, go to the first one again
            if(wayPointIndex > List.Count())
            {
              wayPointIndex = 0;
            }            
            target = List[waypointIndex].transform;      
          }              
        }
    }

Note that you can alterate the code so your controller also moves every enemy, but that's up to you!

Unity C#. How do I link instantiated objects to a pathfinding script and how do I make a gameobject move to a list of nodes?

1 Answers