0.16 Xna0130-collision detection

Revised: Mon May 09 18:37:13 CDT 2016

This page is part of a Book titled XNA Game Studio .

Table of Contents

• Table of Contents
• Preface
  • Viewing tip
    • Figures
    • Listings
• General background information
  • Another improvement
  • Definition of a collision
• Preview
  • An epic battle
    • Spider and ladybug motion
    • The spiders don't die easily
    • The death blow
  • Output screen images
    • The top image
    • The middle image
    • The bottom image
• Discussion and sample code
  • The Sprite class
    • A new Image property accessor method
    • A modified constructor
    • A modified SetImage method
    • A new method named GetRectangle
    • A new method named IsCollision
      • What is a collision?
      • What is the overall behavior?
      • The IsCollision method code
        • Test for a collision with other sprites
        • A while loop
        • The first return statement
        • The second return statement
    • The end of the Sprite class
  • The Game1 class
    • The overridden LoadContent method
      • A background sprite with a spider web image
      • Instantiate the spider and ladybug Sprite objects
    • The overridden Update method
      • A for loop that controls the collision testing
        • Not every spider is tested during each iteration
        • Test for a collision
        • Return a reference to a spider or null
        • If a collision was detected...
        • Why change the spider's position?
        • Spiders don't die easily
        • The Name property
        • Killing the brown spider
        • Is a Dispose Method needed?
      • The end of the Update method
    • The overridden Game.Draw method
  • The end of the program
• Run the program
• Run my program
• Summary
• What's next?
• Miscellaneous
• Complete program listing

Preface

This module is one in a collection of modules designed primarily for teaching GAME 1343 Game and Simulation Programming I at Austin Community College in Austin, TX. These modules are intended tosupplement and not to replace the textbook.

An earlier module titled Getting Started provided information on how to get started programming with Microsoft's XNA Game Studio.

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 Figuresand Listings while you are reading about them.

Figures

• Figure 1 . Screen output at three different times while the program was running.

Listings

• Listing 1 . A new Image property accessor method in the Sprite class.
• Listing 2 . A modified constructor.
• Listing 3 . A modified SetImage method.
• Listing 4 . A new method named GetRectangle.
• Listing 5 . Beginning of a new IsCollision method.
• Listing 6 . Test for a collision with other sprites.
• Listing 7 . Beginning of the overridden LoadContent method of the Game1 class.
• Listing 8 . Instantiate the spider and ladybug Sprite objects.
• Listing 9 . Beginning of the overridden Update method.
• Listing 10 . Beginning of a for loop that controls the collision testing.
• Listing 11 . Test for a collision.
• Listing 12 . Spiders don't die easily.
• Listing 13 . The overridden Game.Draw method.
• Listing 14 . The Sprite class for the project named XNA0130Proj.
• Listing 15 . The Game1 class for the project named XNA0130Proj.