You are previewing Building HTML5 Games with ImpactJS.

Building HTML5 Games with ImpactJS

Cover of Building HTML5 Games with ImpactJS by Jesse Freeman Published by O'Reilly Media, Inc.
  1. Introducing HTML5 Game Development
  2. SPECIAL OFFER: Upgrade this ebook with O’Reilly
  3. A Note Regarding Supplemental Files
  4. Preface
    1. About This Book
    2. Who This Book Is For
    3. Who This Book Is Not For
    4. Conventions Used in This Book
    5. This Book’s Example Files
    6. Using Code Examples
    7. How To Use This Book
    8. Safari® Books Online
    9. How to Contact Us
    10. Acknowledgments
  5. 1. Introduction To Impact
    1. Why Use Impact?
    2. Setting Up a Local Environment
    3. Install WebStorm/PHPStorm
    4. Install Apache/PHP/MySQL
    5. Other Hosting Options
    6. Setting Up a New Impact Project
    7. Modules
    8. How Classes Work
    9. Core Classes
    10. How Inner Classes Work
    11. Level Editor
  6. 2. Working With Sprites
    1. Sprites and Sprite Sheets
    2. Scripting in Photoshop
    3. Working with Sprites in Photoshop
    4. Optimizing Sprites
  7. 3. Introduction To Game Design
    1. What is Game Design?
    2. Sample Game Design Document
      1. Gameplay
      2. Exploring a Map
      3. Combat
      4. Completing a Map
      5. Death
      6. Main Character
      7. Monsters
      8. Bosses
      9. Equipment
      10. Inventory
      11. Equipping Items
      12. Weapons and Armor
      13. Leveling Up
      14. Winning the Game
    3. Coming Up With Ideas
    4. Books to Read
  8. 4. Building A Game
    1. Creating Our First Level
    2. Saving/Loading Maps in Weltmeister
    3. CollisionMaps
    4. The Main Class
    5. Customizing the Main Class
    6. Key Binding
    7. Creating the Player Class
      1. Using Your Sprite Sheet
      2. Adding Simple Physics
      3. Defining Animation Sequences
    8. Creating a Monster Class
    9. Collision Detection
    10. type Property
    11. checkAgainst Property
    12. collides Property
    13. Health
    14. Weapons
    15. Firing the Weapon
    16. Add Multiple Weapons
    17. Killing Entities
    18. Respawning the Player
    19. Create Death Animations
    20. Adding Grenade Explosions
    21. Customizing the Camera
    22. Loading New Levels
  9. 5. Working With Text
    1. Creating Font Sprite Sheets
    2. Adding Text to Your Game
  10. 6. Working With Sound
    1. Adding Sounds
    2. Adding Music
    3. Mobile Browser Sound Compatibility Issues
  11. 7. Creating Game Screens and HUDs
    1. Extending Impact’s Game Class
    2. Creating a Start Screen
    3. Player Stats Screen
    4. Creating the Game Over Screen
    5. Adding In-Game HUD
    6. Game Rewards
    7. In-Game Analytics
  12. 8. Debugging Your Game
    1. Impact’s Debugger
    2. Publishing Your Game
    3. Baking Your Game
    4. Mobile Web Support
    5. Compiling for Native iOS
  13. 9. Wrapping Up
    1. References and Links
  14. About the Author
  15. SPECIAL OFFER: Upgrade this ebook with O’Reilly
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Creating a Start Screen

In order to create our start screen, we are going to need to extend the ig.Game class. We can actually set up each of our game’s screens as inner classes in our main.js file just like we did with other entities in our game. This also allows you to keep all your game screens organized in one file. Add the following code to our main.js module right after the end of our MyGame class but before the ig.main constructor:

You want to start your start screen inner class right before the ig.main constructor.

Figure 7-1. You want to start your start screen inner class right before the ig.main constructor.

Here is the StartScreen class code:

StartScreen = ig.Game.extend({
    instructText: new ig.Font( 'media/04b03.font.png' ),
    background: new ig.Image('media/screen-bg.png'),
    init: function() {
          ig.input.bind( ig.KEY.SPACE, 'start');
    update: function() {
          if(ig.input.pressed ('start')){
    draw: function() {
          var x = ig.system.width/2,
          y = ig.system.height - 10;
          this.instructText.draw( 'Press Spacebar To Start', x+40, y, ig.Font.ALIGN.CENTER );

This should look very familiar to you at this point. We simply extend the ig.Game class, then override a few methods. In init(), we bind the space bar key to start so we can listen for the moment the user is ready to play the game. Next, we override the update method to handle the space bar being pressed. As soon as we detect that ...

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