0.2 Slick0120: starting your program

Table of contents

• Preface
  • Viewing tip
    • Listings
• Preview
• General background information
• Discussion and sample code
  • Two primary objects
    • Behavior of an object of the AppGameContainer class
    • Behavior of an object that implements the Game interface
  • Starting the game
  • The constructors for the AppGameContainer class
  • The setup method of the AppGameContainer class
  • The getDelta method of the GameContainer class
  • The gameLoop method of the AppGameContainer class
• Run the program
• Summary
• What's next?
• Miscellaneous
• Complete program listing

Preface

This module is one in a collection of modules designed to teach you about the anatomy of a game engine.

Although the modules in this collection will concentrate on the Java game library named Slick2D, theconcepts involved and the knowledge that you will gain is applicable to different game engines written in different programming languages as well.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the listings while you are reading about them.

Listings

• Listing 1 . The main method.
• Listing 2 . The start method of the AppGameContainer class.
• Listing 3 . Constructor for the AppGameContainer class that takes a single parameter.
• Listing 4 . Constructor for the AppGameContainer class that takes four parameters.
• Listing 5 . The getDelta method of the GameContainer class.
• Listing 6 . Source code for Slick0120a.java

Preview

The main purpose of this module is to analyze the behavior of the Slick2D game engine when you start aSlick2D game running.

What you have learned

In previous modules, you learned how to download Slick2D and how to install Slick2D in such a way that you can easily compile and execute Slick2D programs fromthe command line with no need for a high level IDE such as Eclipse or NetBeans.

You also learned what we often mean when we speak of a "game engine" and how that terminology relates to a "software framework."

You learned how to write a minimal Java application in conjunction with a set of Slick2D jar files to create your own Slick2D game engine. Using that program asan example, you learned about the overall structure of the Slick2D game engine.

You learned that game engines are typically service provider programs and you learned about a common set of services that is provided by mostgame engines.

You learned about the two cooperating objects that form the heart of the Slick2D game engine.

• An object instantiated from a subclass of the Slick2D class named GameContainer .
• An object instantiated from a class that implements the Slick2D interface named Game .

And last but not least, you learned about the five abstract methods declared in the interface named Game :