One other thing you've probably noticed that your game is missing at this point is some way to make sure you're aiming at the correct place. Typically, this is done by placing a crosshair on the screen. Even though you're working in XNA 3D, you can still draw 2D sprites on the screen, just as you did earlier in the book. Drawing the crosshair on the screen in 2D rather than in the world in 3D will make it a lot easier to work with. Imagine if you wanted it to be drawn in the world in 3D—you'd have to draw it a few units in front of the camera, and every time your camera rotated or moved you'd have to adjust the crosshair accordingly.
When drawing a crosshair on the screen, you can basically "set it and forget it," just like in that annoying rotisserie chicken infomercial. However, this isn't annoying... this is pretty cool stuff. Although...if you're interested in rotisserie chicken ovens, I can get you a sweet deal for five easy installments of only $29.99. But that's a different book—now back to XNA.
The first thing you'll need to do is add an image of a crosshair to your project. To start, create a new folder under the Content node of your project in Solution Explorer for textures. Right-click the Content node in Solution Explorer, select Add → New Folder, and name the new folder Textures.
With the source code for this chapter is a file called crosshair.png in the 3D Game\Content\Textures folder. Add the file to your project by right-clicking the Content\Textures ...