station_obscurum_unity/Assets/Scripts/Enemies/SwarmAnimator.cs

using UnityEngine;
using UnityEngine.VFX;

namespace Enemy
{
    [ExecuteAlways]
    public class SwarmAnimator : MonoBehaviour
    {
        [SerializeField] private VisualEffect vfx;

        [SerializeField] private Rigidbody rb;
        //[SerializeField]
        //private string parameterName = "DeltaVector";

        [SerializeField] private Vector3 avoidancePosDefault;

        [SerializeField] private float explodeDuration = 1.0f;

        private Vector3 currentPosition;
        private float dur;
        private bool isExploding;
        private Vector3 previousPosition;

        // Start is called before the first frame update
        private void Start()
        {
        }

        // Update is called once per frame
        private void Update()
        {
            previousPosition = currentPosition;
            currentPosition = transform.position;
            var velocity = currentPosition - previousPosition;
            vfx.SetVector3("DeltaVector", velocity);

            if (Input.GetKeyDown(KeyCode.Space)) Explode();
            if (isExploding)
            {
                if (dur > explodeDuration) StopExplode();
                dur += Time.deltaTime;
            }
        }

        private void FixedUpdate()
        {
        }

        private void Explode()
        {
            vfx.SetVector3("Avoid", transform.position);
            isExploding = true;
            dur = 0;

            //Wait a sec then stop.
        }

        private void StopExplode()
        {
            vfx.SetVector3("Avoid", avoidancePosDefault);
            isExploding = false;
            vfx.Stop();
        }
    }
}