Smoothly change the player's speed when he leaves the zone - unity3d

Question

I'm trying to make special zone located on ground that accelerates the player, entering which the player's speed increases. When he gets out of it, the speed smoothly returns to the original. But now, when the player leaves the zone, the speed instantly becomes the original. Don't know how to realize it. Please help:)
My code:
PlayerMovement:
[SerializeField] private Rigidbody _rigidoby;
public bool inZone = false;
private void Update()
{
if (inZone == false)
{
_rigidoby.velocity = new Vector3(Input.GetAxis("Horizontal") * Time.deltaTime, 0, Input.GetAxis("Vertical") * Time.deltaTime) * 500;
}
}
SpecialZone:
private Vector3 _cachedVelocity;
private Rigidbody _collisionRigidbody;
[SerializeField] private PlayerMovement _player;
private void OnTriggerStay(Collider other)
{
_player.inZone = true;
if (_collisionRigidbody == null)
{
_collisionRigidbody = other.GetComponent<Rigidbody>();
_cachedVelocity = _collisionRigidbody.velocity;
}
_collisionRigidbody.velocity = new Vector3(Input.GetAxis("Horizontal") * Time.deltaTime, 0, Input.GetAxis("Vertical") * Time.deltaTime) * 1000;
}
private void OnTriggerExit(Collider other)
{
_collisionRigidbody.velocity = _cachedVelocity;
_player.inZone = false;
}

Answer 1

A simple solution can be to gradually decrease the speed in the update once you exit the trigger like this:
private void OnTriggerExit(Collider other)
{
//_collisionRigidbody.velocity = _cachedVelocity;
_player.inZone = false;
}
private void Update()
{
if (inZone == false)
{
_rigidoby.velocity = new Vector3(Input.GetAxis("Horizontal") * Time.deltaTime, 0, Input.GetAxis("Vertical") * Time.deltaTime) * 500;
} else {
If (_collisionRigidbody.velocity > _cachedVelocity;)
_collisionRigidbody.velocity -= 0.01;
}
}
Another could be to launch a coroutine when you exit the trigger.
Alternatively, you could use Vector3.Lerp and set the percent of the speed change in the update like this:
Vector3 _startingSpeedBeforeDeceleration = Vector3.zero;
private void OnTriggerExit(Collider other)
{
//_collisionRigidbody.velocity = _cachedVelocity;
_startingSpeedBeforeDeceleration = _collisionRigidbody.velocity;
_player.inZone = false;
}
float percent = 0f; //from 0 to 1
private void Update()
{
if (inZone == false)
{
_rigidoby.velocity = new Vector3(Input.GetAxis("Horizontal") * Time.deltaTime, 0, Input.GetAxis("Vertical") * Time.deltaTime) * 500;
} else {
If (_collisionRigidbody.velocity > _cachedVelocity;) {
_collisionRigidbody.velocity = Vector3.Lerp(_startingSpeedBeforeDeceleration, _cachedVelocity, percent);
percent += 0,01f;
}
}
}
Not debugged code. Note that I kept the departing speed in the variable _startingSpeedBeforeDeceleration, that is optional, and depends on the movement behaviour you want.
You can play around with Vector3.Lerp for example changing the first argument _startingSpeedBeforeDeceleration as a fixed value, and put there rigidbody speed every time it changes like this Vector3.Lerp(_collisionRigidbody.velocity, _cachedVelocity, percent);, that way you have a smooth start and smooth end, and a top speed change at the middle of the path. Also the percent change can be handled to set the movement behaviour.