Time for action – building the AsteroidManager class

1. Add a new class called AsteroidManager to the Asteroid Belt Assault project.

2. Add the following declarations to the AsteroidManager class:

   Private screenWidth As Integer = 800
   Private screenHeight As Integer = 600
   Private screenPadding As Integer = 10
   
   Private initialFrame As Rectangle
   Private asteroidFrames As Integer
   Private texture As Texture2D
   
   Public Asteroids As List(Of Sprite) = new List(Of Sprite)()
   Private minSpeed As Integer = 60
   Private maxSpeed As Integer = 120
   
   Private rand As Random = new Random()

3. Add a helper method that will be used in the AsteroidManager constructor:

   Public Sub AddAsteroid()
       Dim newAsteroid As Sprite = new Sprite(
           new Vector2(-500, -500), 
           texture, 
           initialFrame, 
           Vector2.Zero)
       for X as Integer = 1 to asteroidFrames - 1 
           newAsteroid.AddFrame(new Rectangle(
               CInt(initialFrame.X) + (initialFrame.Width * x),
               CInt(initialFrame.Y),
            ...