using System;
using UnityEngine;

[RequireComponent(typeof(ParticleSystem))]
public class ParticleGridSnap : MonoBehaviour
{
    [SerializeField, Min(0.01f)] private float _cellSize = 0.2f;

    private ParticleSystem _particleSystem;
    private ParticleSystem.Particle[] _particles = Array.Empty<ParticleSystem.Particle>();

    private void Awake()
    {
        _particleSystem = GetComponent<ParticleSystem>();
    }

    private void LateUpdate()
    {
        int count = _particleSystem.particleCount;
        if (count == 0)
            return;

        if (_particles.Length < count)
            Array.Resize(ref _particles, count);

        count = _particleSystem.GetParticles(_particles);

        for (int i = 0; i < count; i++)
        {
            Vector3 position = _particles[i].position;
            position.x = Mathf.Round(position.x / _cellSize) * _cellSize;
            position.y = Mathf.Round(position.y / _cellSize) * _cellSize;
            _particles[i].position = position;
        }

        _particleSystem.SetParticles(_particles, count);
    }
}