Vector2.MoveTowards not stopping at target position-CodePudding

I am trying to move an object from its current position (on a trigger call) to a target position at a specific speed and make it stop at the target.

This is the code I have:

bool needsToMove = false; 
float speed = 5f;


void OnTriggerEnter2D(Collider2D collision)
{
    needsToMove = true;
}

void FixedUpdate()
{
    MoveDown();
}


void MoveDown()
{
    if (needsToMove)
    {
        Vector2 targetPosition = new Vector2(transform.position.x, transform.position.y - 1f);
        transform.position = Vector2.MoveTowards(transform.position, targetPosition, Speed * Time.deltaTime);
      
    }
    
}

The problem is, that the game object doesn't stop at the target position, it keeps going in the same direction.

I tried adding a coroutine to switch the bool "needsToMove" to false after a couple of seconds but doing that is tedious as I have to pretty much guess the exact time it will take to stop at the target.

Maybe I need to use another method instead of MoveTowards?

CodePudding user response：

This is because your target path depends on the current location, from where the target axis is taken from transform.position it acts like a fox tail and the object is always finding it. There are many ways to solve this problem such as IEnumerator or using Tweener. But there is a simple way to define a destination-oriented function.

public float stopDistance = .2f;
public Vector2 destination;

public void Move()
{
    if (Vector2.Distance(transform.position, destination) <= stopDistance) return;

    transform.position = Vector2.MoveTowards(transform.position, destination, Speed * Time.deltaTime);
}
public void FixedUpdate()
{
    Move();
}

In the above code you just need to enter the destination when a specific event such as OnTriggerEnter, the object stops moving when the distance is below the stopDistance value. To call the Move, set the destination in as below.

void OnTriggerEnter2D(Collider2D collision)
{
    destination = new Vector2(transform.position.x, transform.position.y - 1f);
}

CodePudding user response：

Thanks everyone for making me realize the position was being constantly changed.

What I did to fix was to move the destination/target code to Start()that way the position gets saved and is not being constantly changed on Update()

bool needsToMove = false;
float speed = 5f;
//I added this variable here
Vector2 targetPosition; 


void Start()
{
  //I defined the target position on Start so it is not being constantly changed by Update()
  targetPosition = new Vector2(transform.position.x, transform.position.y - 1f);
}

void OnTriggerEnter2D(Collider2D collision)
{
    needsToMove = true;
}

void FixedUpdate()
{
    MoveDown();
}


void MoveDown()
{
    if (needsToMove)
    {
       //I moved this line to Start(): Vector2 targetPosition = new Vector2(transform.position.x, transform.position.y - 1f);
        transform.position = Vector2.MoveTowards(transform.position, targetPosition, Speed * Time.deltaTime);
      
    }
    
}