How do I make something in the Update function run once, until a certain condition is met (a collision)?,How would I run through this code al the way through in the Update function until it has reached one

Questions & Answers
1

I’m trying to make a game about the immune system because it seems like an interesting idea. This code for a bacteria makes it find a cell and go towards it. However, when I run it, because it is in the Update function, it constantly searches for a new target. How do I make it so that it runs it once, until it actually collides with the target and then runs again. Here’s the code

void Update()
{
    allCells = GameObject.FindGameObjectsWithTag("Cells");
    if(allCells != null){
        index = Random.Range(0, allCells.Length);
        target = allCells[index];
        transform.position = Vector2.MoveTowards(transform.position, target.transform.position, speed * Time.deltaTime);
        transform.up = target.transform.position - transform.position;
    }
}

I am a relatively new unity user and this is the first actual project I am making
,I’m trying to make a game about the immune system because it seems like an interesting idea. This code for a bacteria makes it find a cell and go towards it. However, when I run it, because it is in the Update function, it constantly searches for a new target. How do I make it so that it runs it once, until it actually collides with the target and then runs again. Here’s the code.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class BacteriaMovement : MonoBehaviour
{
private GameObject allCells;
private GameObject target;
public float speed = 5f;
int index;

void Update()
{
    allCells = GameObject.FindGameObjectsWithTag("Cells");
    if(allCells != null){
        index = Random.Range(0, allCells.Length);
        target = allCells[index];
        transform.position = Vector2.MoveTowards(transform.position, target.transform.position, speed * Time.deltaTime);
        transform.up = target.transform.position - transform.position;
    }
}

}

2

You can add a state for your bacteria. It can decide what to do depending on its current state.

    enum BacteriaState { Free, ApproachingCell, AttackingCell } // You can have more states
    BacteriaState state = BacteriaState.Free;
    GameObject target = null;
    float speed = 1;

    void Update()
    {
        switch (state)
        {
            case BacteriaState.Free:
                var allCells = GameObject.FindGameObjectsWithTag("Cells");
                if (allCells != null)
                {
                    var index = Random.Range(0, allCells.Length);
                    target = allCells[index];
                    state = BacteriaState.ApproachingCell; // State transition
                }        
                break;
            case BacteriaState.ApproachingCell:
                if (target != null)
                {
                    transform.position = Vector2.MoveTowards(transform.position, target.transform.position, speed * Time.deltaTime);
                    transform.up = (target.transform.position - transform.position).normalized;
                    if ((target.transform.position - transform.position).magnitude < 0.1f) // You can use other collision detection method
                    {
                        state = BacteriaState.AttackingCell; // State transition
                    }
                }
                break:
            case BacteriaState.AttackingCell:
                // Logic to attack a cell
                // ...
                // After winning:
                state = BacteriaState.Free; // State transition
                target = null; // If target is gone
                break;
            default:
                break;
        }
    }