SFML particle system

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using SFML;
using SFML.System;
using SFML.Graphics;
using SFML.Window;
namespace ConsoleApp1
{


    class MainClass
    {
        private static RenderWindow _window;

        public static void Main(string[] args)
        {
            _window = new RenderWindow(new VideoMode(800, 600), "SFML window");
            ParticleSystem particles = new ParticleSystem(1000);
            Clock clock = new Clock();
            _window.SetVisible(true);
            _window.SetFramerateLimit(60);
            _window.Closed += new EventHandler(OnClosed);
            while (_window.IsOpen)
            {
                Vector2i mouse = Mouse.GetPosition(_window);
                //Console.WriteLine(mouse.X + " " + mouse.Y);
                particles.SetEmitter(new Vector2f(mouse.X, mouse.Y));
                particles.update(clock.Restart());
                _window.DispatchEvents();
                _window.Clear(Color.Black);
                _window.Draw(particles);
                _window.Display();

            }
        }

        private static void OnClosed(object sender, EventArgs e)
        {
            _window.Close();
        }
    }
    class ParticleSystem : Transformable, Drawable
    {
        public VertexArray m_vertices;
        public Time m_lifetime;
        public List<Particle> m_particles;
        public Vector2f m_emitter;

        public ParticleSystem(int count)
        {
            m_particles = new List<Particle>(count);
            m_vertices = new VertexArray(PrimitiveType.Points, (uint)count);
            m_lifetime = Time.FromSeconds(count);
            m_emitter = new Vector2f(0, 0);
            for(int i = 0; i<count; i++)
            {
                m_particles.Add(new Particle());
                resetParticle(i);
            }
        }
        public void Draw(RenderTarget target, RenderStates states)
        {
            states.Texture = null;
            states.Transform *= Transform;
            target.Draw(m_vertices, states);
        }
        public void SetEmitter(Vector2f newEmitter)
        {
            m_emitter = newEmitter;
            Console.WriteLine(newEmitter.X + " " + newEmitter.Y);
        }
        public void update(Time elapsed)
        {
            for (int i = 0; i < m_particles.Count; ++i)
            {
                // update the particle lifetime
                Particle p = m_particles[i];
                p.lifetime -= elapsed;

                m_particles[i] = p;

                // if the particle is dead, respawn it
                if (p.lifetime <= Time.Zero)
                    resetParticle(i);

                // update the position of the corresponding vertex
                var a = m_vertices[(uint)i];
                a.Position += p.velocity * elapsed.AsSeconds();


                // update the alpha (transparency) of the particle according to its lifetime
                float ratio = p.lifetime.AsSeconds() / m_lifetime.AsSeconds();
                a.Color = Color.White;
                a.Color.A = (byte)(ratio * 255);
                m_vertices[(uint)i] = a;
            }
        }
        void resetParticle(int index)
        {
            // give a random velocity and lifetime to the particle
            float angle = (new Random().Next() % 360) * 3.14f / 180;
            float speed = (new Random().Next() % 50) + 50;
            var temp = m_particles[index];
            temp.velocity = new SFML.System.Vector2f((float)(Math.Cos(angle) * speed), (float)(Math.Sin(angle) * speed));
            temp.lifetime = Time.FromMilliseconds((new Random().Next() % 2000) + 1000);
            m_particles[index] = temp;
            // reset the position of the corresponding vertex
            var temp2 = m_vertices[(uint)index];
            temp2.Position = m_emitter;
            m_vertices[(uint)index] = temp2;
        }
        public class Particle
        {
            public Vector2f velocity;
            public Time lifetime;
        }
    }
}