25 600 движущихся спрайтов

using System;
using System.Diagnostics;
using System.Threading;
using UnityEngine;
using Particle = UnityEngine.ParticleSystem.Particle;
 
public class Spawner : MonoBehaviour
{
    [SerializeField] int GridSizeX = 160;
    [SerializeField] int GridSizeY = 160;
    [SerializeField] float GridStep = 1;
    [SerializeField] float AtomRadius = 0.5f;
    [SerializeField] float AtomSpeed = 5f;
    [SerializeField] ParticleSystem ps;
 
    Particle[] particles;
    int[] collisionMatrix;
    float matrixStep;
    int matrixSizeX;
    int matrixSizeY;
    float maxX, maxY;
    Vector3 spawnAfterCollisionPosition = new Vector3(-100, -100, 0);
 
 
    void Start()
    {
        maxX = GridSizeX * GridStep;
        maxY = GridSizeY * GridStep;
        matrixStep = 1 / AtomRadius;
        matrixSizeX = 1 + (int)(maxX * matrixStep);
        matrixSizeY = 1 + (int)(maxY * matrixStep);
        collisionMatrix = new int[matrixSizeX * matrixSizeY];
 
        SpawnGrid();
    }
 
    public void OnStart()
    {
        ThreadPool.QueueUserWorkItem(UpdateParticles);
    }
 
    private int PosToMatrixIndex(Vector3 pos)
    {
        if (pos.x < 0 || pos.y < 0 || pos.x > maxX || pos.y > maxY) return -1;
        var i = Mathf.RoundToInt(pos.x * matrixStep);
        var j = Mathf.RoundToInt(pos.y * matrixStep);
        return i + j * matrixSizeX;
    }
 
    private void UpdateParticles(object state)
    {
        float dt = 0f;
        var sw = new Stopwatch();
 
        while (true)
        {
            sw.Restart();
 
            //update position
            for (int i = 0; i < particles.Length; i++)
                particles[i].position += particles[i].velocity * dt;
 
            dt = sw.ElapsedMilliseconds / 1000f;
 
            //clear collision matrix
            Array.Clear(collisionMatrix, 0, collisionMatrix.Length);
 
            //fill matrix, detect collisions
            for (int i = 0; i < particles.Length; i++)
            {
                var index = PosToMatrixIndex(particles[i].position);
                if (index < 0)
                    continue;
 
                if (collisionMatrix[index] > 0)
                {
                    //collision detected
                    particles[i].position = spawnAfterCollisionPosition;
                    particles[collisionMatrix[index] - 1].position = spawnAfterCollisionPosition;
                    collisionMatrix[index] = 0;
                    continue;
                }
 
                //put particle index + 1 to collision matrix
                collisionMatrix[index] = i + 1;
            }
        }
    }
 
    private void SpawnGrid()
    {
        particles = new Particle[GridSizeY * GridSizeX];
 
        for (int i = 0; i < GridSizeX; i++)
        for (int j = 0; j < GridSizeY; j++)
        {
            var index = i + j * GridSizeX;
            var pos = new Vector2(i * GridStep, j * GridStep);
            var vel = UnityEngine.Random.insideUnitCircle * AtomSpeed;
            particles[index].position = pos;
            particles[index].startColor = Color.white;
            particles[index].startSize = AtomRadius;
            particles[index].velocity = vel;
        }
    }
 
    void Update()
    {
        ps.SetParticles(particles, particles.Length);
    }
}