XNA 4.0 Game Development by Example Beginner's Guide

Time for action – updating and drawing the EnemyManager

1. Add the Update() method to the EnemyManager class:

   public void Update(GameTime gameTime)
   {
       EnemyShotManager.Update(gameTime);
   
       for (int x = Enemies.Count - 1; x >= 0; x--)
       {
           Enemies[x].Update(gameTime);
           if (Enemies[x].IsActive() == false)
           {
               Enemies.RemoveAt(x);
           }
           else
           {
               if ((float)rand.Next(0, 1000) / 10 <= shipShotChance)
               {
                   Vector2 fireLoc = Enemies[x].EnemySprite.Location;
                   fireLoc += Enemies[x].gunOffset;
   
                   Vector2 shotDirection =
                       playerManager.playerSprite.Center -
                       fireLoc;
   
                   shotDirection.Normalize();
                   EnemyShotManager.FireShot(
                       fireLoc, 
                       shotDirection, 
                       false);
               }
           }
       }
   
       if (Active)
       {
           updateWaveSpawns(gameTime);
       }
   }

2. Add the Draw() method to the EnemyManager class:

   public void Draw(SpriteBatch spriteBatch) ...