0.11 Slick0210: collision detection and sound

Table of contents

• Preface
  • Viewing tip
    • Figures
    • Listings
• Preview
• General background information
• Discussion and sample code
  • The class named Sprite01
  • The class named Slick0210
    • The init method
    • The update method
    • The isCollision method of the Sprite01 class
    • The render method
• Run the program
• Summary
• What's next?
• Miscellaneous
• Complete program listings

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.

The purpose of this module is to teach you how to use the Sprite01 class developed in an earlier module titled Slick0200: Developing a sprite class to write a predator/prey simulation program involving thousands of sprites along with collision detection and sound effects.

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 imagesand listings while you are reading about them.

Figures

• Figure 1 . Graphic output near the beginning of the simulation.
• Figure 2 . Graphic output near the middle of the simulation.
• Figure 3 . Graphic output near the end of the simulation.
• Figure 4 . Output for the harmless blue sprite scenario.

Listings

• Listing 1 . Beginning of the class named Slick0210.
• Listing 2 . Beginning of the init method.
• Listing 3 . Add a red sprite to the ArrayList object.
• Listing 4 . Populate the ArrayList object.
• Listing 5 . Beginning of the update method.
• Listing 6 . Test for a collision.
• Listing 7 . The isCollision method of the Sprite01 class.
• Listing 8 . Process a collision
• Listing 9 . Remove dead objects from the ArrayList object.
• Listing 10 . The render method.
• Listing 11 . Source code for the program named Slick0210.
• Listing 12 . Source code for the class named Sprite01.

Preview

In an earlier module titled Slick0200: Developing a sprite class , we encountered a baseball coach that had been attacked by a swarm of viciousladybug sprites. I promised you that we would later find a way to save the coach. That time has come.

In this module, I will explain a program that uses the Sprite01 class from the earlier module to produce a simulation program with the outputshown in Figure 1 , Figure 2 , and Figure 3 .

A swarm of insects

Once again, the coach has been attacked by a swarm of 1000 insects. However, in this case, the ladybug sprites have been replaced by vicious green beetlesprites.

A red predator beetle

Fortunately for the coach, a red predator beetle sprite with a taste for green beetles has come along and is gobbling up green beetles as fast as he cancollide with them. (According to the text at the top of Figure 1 , 152 of the 1000 beetles had been consumed by the time the screen shot in Figure 1 was taken.)