0.16 Xna0130-collision detection  (Page 8/9)

There is nothing new in Listing 13 . However, the call to spiderWeb.Draw is a little different from the code that you have seen in the overridden Game.Draw methods in the last couple of modules. This code calls the Sprite.Draw method, which in turn calls the SpriteBatch.Draw method to draw the image of the spider web as a background image in Figure 1 .

The end of the program

Listing 13 also signals the end of the overridden Game.Draw method, the end of the Game1 class, and the end of the program.

Run the program

I encourage you to copy the code from Listing 14 and Listing 15 . Use that code to create an XNA project. You should be able to find anddownload suitable image files from the web. Any small images can be used as substitutes for the spiders and the ladybugs. A larger image can be used for thebackground.

Compile and run the project. Experiment with the code, making changes, and observing the results of your changes. Make sure that you can explainwhy your changes behave as they do.

Run my program

Click here to download a zip file containing my version of the program. Extract the folder named XNA0130Proj from the zip file and save it somewhere on your disk. Start Visual C# 2010 Express and select Open Project... from the File menu. Navigate to the project folder and select the file with the extension of .sln . This should cause the project to open and be ready to run or debug as described in the earlier module titled Getting Started .

Summary

You learned how to design and create a Sprite class that provides collision detection. You also learned how to write an XNA program thattakes advantage of that collision detection capability.

What's next?

The one critical element that is preventing us from using the Sprite class to create a 2D arcade style game is the ability of the user to control themotion of one or more sprites using keyboard and/or mouse input. That will be the topic for the next module.

Once we have that tool, we can write a game where the challenge is to prevent the spiders from successfully navigating across the game window without beingeaten by a ladybug. Or, we could write a game where the challenge is to cause the ladybugs to successfully navigate across the game window without beingbitten by a spider.

Beyond that, there are several other tools that will make it possible for us to create more sophisticated and interesting games:

• The ability to play sounds.
• The ability to create onscreen text.
• The ability to create a game with multiple levels and increasing difficulty at each level, scorekeeping, etc.

I will show you how to create some of those tools later in this series ofmodules and will leave others as an exercise for the student.

Miscellaneous

This section contains a variety of miscellaneous information.