How to instantly stop when moving the character with AddForce?

Question

I made character movement using AddForce. But I don't understand how to get the desired effect. I need that when I release a movement key (for example WASD) the character stops instantly or almost instantly, but when using AddForce it slides for a while after releasing the movement key.

For example

private void FixedUpdate()
{
 moveHorizontal = Input.GetAxis("Horizontal");
 moveVertical = Input.GetAxis("Vertical");
 _direction = new Vector3(moveHorizontal,0, moveVertical);
 _rigidbody.AddForce(_direction * _speed);
}

I don't want to change any Rigidbody or gravity properties, because it might cause other problems and affect other objects in the scene.

• DMGregory: I usually solve this using an AccelerateTowards method that applies forces to match a target velocity — including using forces to slow down and stop when the target is zero. This answer shows a simple version. This other answer shows a slightly more elaborate version where you can apply a stronger stopping force, while keeping the acceleration gradual when speeding up

Answer 1

private void FixedUpdate()
{
 float moveHorizontal = Input.GetAxis("Horizontal");
 float moveVertical = Input.GetAxis("Vertical");
 Vector3 _direction = new Vector3(moveHorizontal, 0, moveVertical);
 if (_direction.magnitude > 0.01f)
 {
 _rigidbody.AddForce(_direction.normalized * _speed);
 }
 else
 {
 _rigidbody.velocity = Vector3.zero;
 _rigidbody.angularVelocity = Vector3.zero;
 }
}

This will stop immediately if no input. When you press a key Horizontal or Vertical the value of it will be between [-1, 1] so the Vector3.magnitude obviously > 0.01 and if you're not press anything then you can stop the Rigidbody. It has been 2 years since my last code in Unity. If it wrong please let me know :v

• DMGregory: May I ask why you deleted this answer? It looks reasonable to me, though I'd tweak the check to if (direction.sqrMagnitude > 0f)
• Tiên Hưng: Something just through out my mind that it was wrong and I 'm going to install Unity and check again so I was temporarily delete my answer