c# - Changing the player's position in Update() or FixedUpdate() method?

Question

In my game I've a case that when the player is touching the collider of a specific GameObject and the player press the X key I want to change his position to the position of another GameObject.

To do that I use the following code

void FixedUpdate()
{
    if (Input.GetKeyDown(KeyCode.X))
    {
        // Check Colliders collition
        // End of Check Colliders collition

        var playerRigidBody = GetComponent<Rigidbody2D>();
        playerRigidBody.position = AnotherObject.transform.position;
    }
}

I've realized that very often when I press the X key the player don't change his position to the position of the other GameObject. However if I move the code to the Update() method it works as expected (with no delay).

But I've read in the official documentation and in a lot of blogs that the code related to physics and Rigidbodies must be put in the FixedUpdate instead of Update

So the question is the following:

For this case putting the code in the Update() method is not recommended? (Note that I'm not using forces nor torques)

If it's not recommended then how can I assure that every time the player press the X key he will change his position to the other GameObject position in FixedUpdate()?

标签： c#unity3d

Answer 1

In general if you want a smooth movement you should rather use MovePosition in FixedUpdate otherwise everything regarding Physics (so also RigidBody) you should always do in FixedUpdate (as explained in the API there as well).

---

You should however catch the GetKeyDown in Update and split those two things:

bool wasClicked;
RigidBody playerRigidBody;

void Start()
{
    // do this only once!
    playerRigidBody = GetComponent<Rigidbody2D>();
}

void Update()
{
    // Catch user input here

    if (Input.GetKeyDown(KeyCode.X))
    {
        wasClicked = true;
    }
}

void FixedUpdate()
{
    // Handle physics here

    if(!wasClicked) return;

    playerRigidBody.position = AnotherObject.transform.position;

    wasClicked = false;
}