University of the West of England, Bristol

Department of Computer Science and Creative Technologies

C# XNA Worksheet 5 - Making a Working Game

C# 2010 - XNA Version 4

Learning Aims

This worksheet combines all you've learned in the previous worksheets to build a small, working game. Although you've done all the various parts separately, bringing everything into one working application is far from easy: you get an explosion of complexity and you need a clear head to work your way through it.

To get the most out of this worksheet you should do the following:

• Print out this page and work from the printed version
• Read through all the practical steps before making a start
• Have your lecture notes beside you and refer to them as you work.
• Put in the necessary time to complete ALL of the worksheet.
• DO NOT BE IN A HURRY TO FINISH. This is NOT a race and it is more important to understand and remember what you've done rather than finish before your friends.

If You Get Interrupted

If you are unable to finish any of these worksheets in one go, then this is what you should do to make sure that you can resume it from the point you finished, without having to start from scratch:

• To stop XNA Game Studio:
  • Click on the X at the top right of the main window.
  • If asked to save any files, always select Yes
  • At this point, the IDE may ask you to choose a folder to save the project. Click on the Browse button and navigate to the folder of your choice, then click on Save:
    
• To restart XNA Game Studio:
  • Start XNA Game Studio
  • Re-load the project by clicking on the project name in the main window. After clicking, loading will take several seconds so be patient.

Practical Steps- What You Have to Do

Unlike the previous worksheets where you've been led my the hand, in this case I want you to think...

Using what you've learned so far about XNA, create a game which works like this:

1. A fully inflated balloon rests near the bottom left hand corner of the screen, whilst a dart rests near the bottom left corner.

2. At some random time, the balloon is released at a random angle and flies upwards and across the screen, deflating as it does so. When it's fully deflated the balloon drops to the bottom of the screen.

3. The user may fire the dart at the balloon. If the dart hits the balloon before it's fully deflated then the balloon pops and the score is increased by 10.

4. The sequence repeats at regular intervals.

You should use your experience to tailor the parameters of the game to make it as playable as possible...

You should use the graphical assets provided for worksheet one: Worksheet Assets

Tidying Up When You've Finished

When you've finished all the steps above, you need to close down Game Studio Express as follows:

• Click on the X on the main XNA Game Studio window.
• If it asks you to save changes, always click on Save
  
• At this point, you may asked to choose a folder to save the project. Click on the Browse button and navigate to the folder of your choice, then click on Save.

Aargghh! I Can't Get My Head Around This!

Even with a simple game like this, you can easily get in a mess. You can find yourself forgetting which variables correspond to which screen object, or if you're really unfortunate you can find yourself in an awkward situation where trying to fix one error introduces another, and fixing that introduces yet another, and so on...

The real difficulty is that the simple techniques we've used so far don't scale up into bigger programs. We're missing some tools from out coding toolkit. There are:

• Using Object Orientated programming to encapsulate each sprite's data and automate its movement on each call to Update.
• Using Finite State Design to model the life-time of each sprite.

These topics will be covered in your remaining lectures this term, and you will soon learn to apply them to your semester one coursework assignment!