Time for action –building the rover

To build the player's rover, perform the following steps:

1. 1. Add a new class file called Rover.cs to the Mars Runner project.

2. 2. Add the following using directives to the top of the Rover class file:

   using Microsoft.Xna.Framework;
   using Microsoft.Xna.Framework.Graphics;

3. 3. Modify the declaration of the Rover class to inherit from GameEntity. The new class declaration should read as follows:

   class Rover : GameEntity

4. 4. Add a constructor for the Rover class as follows:

   #region Constructor
   public Rover(GraphicsDevice device, Model model, Vector3 position)
       : base(device, model, position)
   {
       scale = 0.015f;
       yaw = MathHelper.ToRadians(90);
       currentTransforms["canon_geo"] = 
           Matrix.CreateRotationX(MathHelper.ToRadians(-90)) * 
           baseTransforms["canon_geo"];
   }
   #endregion

5. 5. In the MarsRunnerPlayScreen class, add a new field to hold an instance of the Rover class as follows:

   Rover rover;

6. 6. In the LoadContent() method of the MarsRunnerPlayScreen...