I can't make Player gameObject bounce off of objects

Questions & Answers
1

I am trying to make a Player GameObject bounce off of another object with a tag “Obstacle”.

  1. Player: Dynamic 2D Rigidbody + Circle Collider 2D
  2. Obstacle: Tilemap Collider 2D
  3. Collision is detected, however the velocity doesn’t seem to change.

Issue: The Player GameObject doesn’t seem to bounce off. I tried placing print statement that shows the velocity of the rigidbody at the start and end of the OnCollisionEnter2D method, but they both show (0.00, 0.00).

What could I possibly be doing wrong?

Here’s my code in the PlayerMove Script:

Start

void Start(){ rb = gameObject.GetComponent<Rigidbody2D>();}

FixedUpdate

private void FixedUpdate(){ 
        rb.MovePosition(rb.position + moveDir * playerStats.PLAYERSPEED * Time.fixedDeltaTime);
}

OnCollisionEnter2D

private void OnCollisionEnter2D(Collision2D other) {
    if (other.gameObject.CompareTag("Obstacle")) {
        //print rb.velocity #1
        float _speed = rb.velocity.magnitude;
        Vector2 _objectNormal = other.contacts[0].normal.normalized;
        moveDir = Vector2.Reflect(rb.velocity, _objectNormal);

        rb.velocity = moveDir * _speed;
        //print rb.velocity #2
    }
}
2

I think you would be better off having the velocity of the rigidbody on the previous frame. Just store a previousVelocity vector var in Update each frame and use that for your reflect method. You can also get the collision force via the following, but it doesn’t tell you the previous frame’s velocity:

var collisionForce = other.impulse / Time.fixedDeltaTime;

I would personally go with the previous frame velocity as it should be a fairly trivial and reliable approach. I use it all the time.