How to calculate distance between objects?

• Use SphereCast to get gameobjects in certain radius, then loop through them and get whatever you want.

• Use Vector3.Distance to get the distance.

okay, simple example of finding the closest object with a tag

 GameObject FindClosestTag(string tag){
 
   //get all the gameobjects with a tag
   GameObject[] tagged = GameObject.FindGameObjectsWithTag(tag);
   //closest object found so far
   GameObject closest = null;
   //the shortest distance we've found so far
   float shortestDistance = float.PositiveInfinity;
   //loop trough all gameobjects we found with the tag
   foreach(GameObject go in tagged){
    //we don't want to have ourself be an option for the closest object
    if(go != this.gameObject){
      //the distance to the current gameobject
      float currentDistance = Vector3.Distance(transform.position, go.transform.position);
      //this object is closer than the closest one so far 
      //this one becomes the closest one so far
      if(currentDistance < shortestDistance){
       shortestDistance = currentDistance;
       closest = go;
      }
    }
   }
 
  //return the gameobject we found
  return closest;
 }

not a very optimized code snip, but should do what you need.

Here is some code to get you started on how to move towards another object within a certain distance:

 using UnityEngine;
 using System.Collections;
 
 public class ObjectA : MonoBehaviour {
 
     // The distance beneath which objectA will move towards objectB in world units
     public float searchRadius = 10f;
 
     // Speed of this object when moving towards the target
     public float speed = 1f;
 
     // The target to follow
     private GameObject objectB;
 
     // Our own rigidbody
     private Rigidbody2D rb;
 
 
     void Start () {
 
         // Get the rb2D component from this object
         rb = GetComponent<Rigidbody2D>();
 
         // Find the other object by Tag, it must already exist on scene creation
         objectB = GameObject.FindGameObjectWithTag("tagofObjectB");
     }
 
     // FixedUpdate because we are moving rigidbody that need to be in sync with other Physics actions
     void FixedUpdate () {
 
         // Calculate the distance between both objects
         float distance = Vector3.Distance(objectB.transform.position, transform.position);
 
         // If the distance is smaller than the given threshold
         if(distance < searchRadius) {
 
             // Calculate the direction from our object to objectB
             Vector2 direction = objectB.transform.position - transform.position;
 
             // Move with our rigidbody towards the other object in a straight line
             // Can be stopped by other colliders or forces
             rb.MovePosition(rb.position + direction * speed * Time.fixedDeltaTime);
         }
     }
 }

Try this out dude. It's what I'm currently doing now to determine the distance of my AI Character and Player. So like if it's too close then he'll do this thingy and if far away he'll do something else.

     public Vector2 RelativePoint;
     public Transform YourTransform;
 
 
 
 
         if(YourTarget != null){
         RelativePoint = YourTransform.InverseTransformPoint(YourTarget.transform.position);
 
         }

Attach this code to your Character or what ever object you'd like to use then

Drag Your GameObject with the script into the YourTransform

And then next

Create a GameObject (or not) Drag that GameObject into your public Gameobject named YourTarget

Start the game and you'll see numbers ranging in your Public Vector RelativePoint.

Pretty simple man. It works for me, I hope it does the same for you as well.

: )

Ok, i saw my error, i actually do everything right, only i use incorrectly the "go" in: foreach (GameObject go in tagged)