Oyyou.MonoGameTutorials/MonoGame_Tutorials/Tutorial020/Managers/EnemyManager.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tutorial020.Sprites;

namespace Tutorial020.Managers
{
  public class EnemyManager
  {
    private float _timer;

    private List<Texture2D> _textures;

    public bool CanAdd { get; set; }

    public Bullet Bullet { get; set; }

    public int MaxEnemies { get; set; }

    public float SpawnTimer { get; set; }

    public EnemyManager(ContentManager content)
    {
      _textures = new List<Texture2D>()
      {
        content.Load<Texture2D>("Ships/Enemy_1"),
        content.Load<Texture2D>("Ships/Enemy_2"),
      };

      MaxEnemies = 10;
      SpawnTimer = 2.5f;
    }

    public void Update(GameTime gameTime)
    {
      _timer += (float)gameTime.ElapsedGameTime.TotalSeconds;

      CanAdd = false;

      if (_timer > SpawnTimer)
      {
        CanAdd = true;

        _timer = 0;
      }
    }

    public Enemy GetEnemy()
    {
      var texture = _textures[Game1.Random.Next(0, _textures.Count)];

      return new Enemy(texture)
      {
        Colour = Color.Red,
        Bullet = Bullet,
        Health = 5,
        Layer = 0.2f,
        Position = new Vector2(Game1.ScreenWidth + texture.Width, Game1.Random.Next(0, Game1.ScreenHeight)),
        Speed = 2 + (float)Game1.Random.NextDouble(),
        ShootingTimer = 1.5f + (float)Game1.Random.NextDouble(),
      };
    }
  }
}