Move object back automatically

Questions & Answers
1

public var goTransform:Transform;
private var vel:int = 2;//how fast the game object is being moved

function Awake()  
{  
    //get this GameObject's Transform  
    goTransform = this.GetComponent(Transform);  
}  
  
// Update is called once per frame  
function Update()  
{  
    //moves the containing GameObject forward  
    goTransform.position.z = goTransform.position.z + vel;  
}

with this script you can make an object move forward automatically.

What should I change to get the object back in the opposite direction?

2

You can use:

or a sin/cos fct since they are naturally going from -1 to 1 and on again non stop.

Final way is lerping either with Mathf.Lerp/MoveTowards or Vector3.Lerp/MoveTowards. Those require that you check if you reach the target then set it back to the opposite one:

var target:Transform[];
var index : int = 0;
var ratio : float = 0.5f;
function Update()
{
    if(transform.position == target[index])
    {
        if(++index == target.Length)
        {
             index = 0;
        }
    }
    transform.position = Vector3.Lerp(transform.position, target[index], ratio * Time.deltaTime);
}