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- Herausgeber: Packt Publishing
- Kategorie: Fachliteratur
- Sprache: Englisch
Key Features
Book Description
This book is for web designers who have a basic knowledge of HTML, CSS, and JavaScript and want to create Canvas or DOM-based games that run on browsers.What you will learn
- Build realtime network multiplayer games
- Add physics to your canvas games by using the Box2D physics engine
- Build a CSS3driven card game with transform and 3D flipping effects
- Learn to add sounds to your games
- Make a drawing tool in Canvas
- Create multiple layers in a canvas game
- Store game data persistently by using local storage
- Use sprite sheets to create framebased animation
Who this book is for
This book is for web designers who have a basic knowledge of HTML, CSS, and JavaScript and want to create Canvas or DOM-based games that run on browsers.
Das E-Book können Sie in Legimi-Apps oder einer beliebigen App lesen, die das folgende Format unterstützen:
Seitenzahl: 389
Veröffentlichungsjahr: 2015
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Table of Contents
HTML5 Game Development by Example Beginner's Guide Second Edition
HTML5 Game Development by Example Beginner's Guide Second Edition
Copyright © 2015 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: August 2011
Second edition: June 2015
Production reference: 2250615
Published by Packt Publishing Ltd.
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ISBN 978-1-78528-777-0
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Credits
Author
Makzan
Reviewers
Lauri Hosio
Dan Nagle
Matt Palmerlee
Leonardo Risuleo
Commissioning Editor
Dipika Gaonkar
Acquisition Editors
Vivek Anantharaman
Sam Wood
Content Development Editor
Arwa Manasawala
Technical Editor
Menza Mathew
Copy Editors
Ameesha Green
Jasmine Nadar
Project Coordinator
Shweta H Birwatkar
Proofreader
Safis Editing
Indexer
Tejal Daruwale Soni
Production Coordinator
Manu Joseph
Cover Work
Manu Joseph
About the Author
Makzan focuses on the fields of web development and game design. He has over 14 years of experience in building digital products. He has worked on real-time multiplayer interaction games, iOS applications, and rich interactive websites.
He has written three books, on building a Flash virtual world, and creating games with HTML5 and the latest web standards and developed a video course as well. He currently teaches courses in Hong Kong and Macao SAR. He writes tutorials and shares his know-how on makzan.net.
I wish to thank my wife, Candy, for her patience and understanding. I would also like to thank the entire team at Packt Publishing. The book would not have been possible without their help. I thank all the reviewers for providing useful comments from which I have learned a lot.
About the Reviewers
Lauri Hosio has been making games since he discovered QBASIC with his friends in elementary school. Professionally, he's worked with web and mobile games for over 7 years.
Previously, he worked at Rovio as the acting lead game programmer on Angry Birds Friends. At other companies, he has also worked on web-based MMO games and general web development.
Before HTML5, he made independent web games with Flash that were played by millions of players. Some of his games have been published by AddictingGames and ArmorGames. Lauri currently works in Kansas City, Missouri, on mobile games and full-stack web development.
Dan Nagle has, since graduating as a valedictorian in computer engineering from the Mississippi State University in 2003, written and published apps for Android, Windows, Mac, Linux, iOS, numerous web apps, network servers, and pure embedded C. He is the author of the book, HTML5 Game Engines: App Development and Distribution, which was published by CRC Press. He has also written articles and spoken at conferences about developing websites and HTML5-based games.
For about 4 years, he owned and operated a web company that focused on website hosting and custom game development. Before that, he was an electrical engineer who developed embedded systems.
Currently, he is a senior software engineer who writes control software, web interfaces, and mobile apps for network devices that distribute HD video. He can be reached through his website at http://DanNagle.com/.
Matt Palmerlee has been developing software professionally since 2001 and has a passion for JavaScript and HTML5 game development. He built Astriarch, an open source multiplayer space strategy game, using HTML5 and Node.js. Matt has developed other HTML5 games, which were published by Mastered Software, his software development consulting company.
Matt occasionally blogs about interesting aspects of software development and HTML5 games on his personal website at http://mattpalmerlee.com/.
Leonardo Risuleo is the owner and creative director of Small Screen Design. He is a designer and developer with several years of experience in mobile, new media, and user experience. Leonardo is a highly dedicated professional, and he's passionate about what he does. He started his career in 2003, and in the last few years, he has worked on a variety of different mobile and embedded platforms for a number of well-known brands and studios. Leonardo designs, prototypes, and develops mobile applications, games, widgets, and websites.
From 2008 to 2010, he had the honor of being the Nokia Developer Champion, a recognition and reward program for top mobile developers worldwide. In 2008, Leonardo formally founded Small Screen Design (https://www.smallscreendesign.com), a design and development studio focused on mobile design and user experience. In 2015, he became Digital Champion—an ambassador for the Digital Agenda—for Squillace, to help every European become digital.
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Preface
HTML5 promises to be the hot new platform for online games. HTML5 games work on computers, smartphones, tablets, iPhones, and iPads. Be one of the first developers to build HTML5 games today and be ready for tomorrow!
This book will show you how to use the latest HTML5 and CSS3 web standards to build card games, drawing games, physics games, and even multiplayer games over the network. With this book, you will build six example games with clear systematic tutorials.
HTML5, CSS3, and the related JavaScript API are the latest hot topic in the Web. These standards bring us the new game market of HTML5 games. With the new power from them, we can design games with HTML5 elements, CSS3 properties, and JavaScript to play in browsers.
The book is divided into 10 chapters with each one focusing on one topic. While building the six games in the book, you will learn how to draw game objects, animate them, add audio, connect players, and build physics game with the Box2D physics engine.
What this book covers
Chapter 1, Introducing HTML5 Games, introduces the new features of HTML5, CSS3, and the related JavaScript API. It demonstrates what games we can make with these features and their benefits.
Chapter 2, Getting Started with DOM-based Game Development, kickstarts the game development journey by creating a traditional Ping Pong game in DOM and jQuery.
Chapter 3, Building a Card-matching Game in CSS3, walks you through the new features of CSS3 and discusses how we can create a memory card-matching game in DOM and CSS3.
Chapter 4, Building the Untangle Game with Canvas and the Drawing API, introduces a new way to draw things and interact with them in a web page with the new canvas element. This also demonstrates how to handle dragging on touch devices.
Chapter 5, Building a Canvas Game's Masterclass, extends the Untangle game to show how we can draw gradients and images in the Canvas. It also discusses sprite sheet animations and multilayer management.
Chapter 6, Adding Sound Effects to Your Games, adds sound effects and background music to the game by using the Audio element. It discusses the audio format capability among web browsers and creates a keyboard-driven music game by the end of the chapter.
Chapter 7, Saving the Game's Progress, extends the CSS3 memory-matching game to demonstrate how we can use the Local Storage API to store and resume game progress and records the best scores.
Chapter 8, Building a Multiplayer Draw-and-Guess Game with WebSockets, discusses the WebSockets API that allows browsers to establish persistent connection with the socket server. This allows multiple players to play the game together in real time. A draw-and-guess game is created at the end of the chapter.
Chapter 9, Building a Physics Car Game with Box2D and Canvas, teaches you how to integrate a famous physics engine, Box2D, into our canvas games. It discusses how to create physics bodies, apply force, connect them together, associate graphics with the physics, and finally create a platform car game.
Chapter 10, Deploying HTML5 Games, shares the different ways in which we can publish our games. It discusses wrapping the web into a native app for Apple's App Store.
Appendix, Pop Quiz Answers, gives the answers to the pop quiz questions in each of the chapters.
What you need for this book
You need the latest modern web browsers, a good text editor, and a basic knowledge of HTML, CSS, and JavaScript. In Chapter 8, Building a Multiplayer Draw-and-Guess Game with WebSockets, we need the Node.js server, which we will help you to install in that chapter.
Who this book is for
This book is for web designers who have a basic knowledge of HTML, CSS, and JavaScript and want to create Canvas or DOM-based games that run on browsers.
Sections
In this book, you will find several headings that appear frequently (Time for action, What just happened?, Pop quiz, and Have a go hero).
To give clear instructions on how to complete a procedure or task, we use these sections as follows:
Time for action – heading
Instructions often need some extra explanation to ensure they make sense, so they are followed with these sections:
What just happened?
This section explains the working of the tasks or instructions that you have just completed.
You will also find some other learning aids in the book, for example:
Pop quiz – heading
These are short multiple-choice questions intended to help you test your own understanding.
Have a go hero – heading
These are practical challenges that give you ideas to experiment with what you have learned.
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Chapter 1. Introducing HTML5 Games
Hypertext Markup Language, HTML, has been shaping the Internet in the last few decades. It defines how content is structured in the Web and the linkage between related pages. HTML has kept evolving from version 2 to HTML 4, and later to XHTML 1.1. Thanks to the web applications and social networking applications, it the era of HTML5 now.
Cascading Style Sheet (CSS) defines how web pages are presented visually. It styles all HTML elements and the styles of their states, such as hover and active.
JavaScript is the logic controller of a web page. It makes the web page dynamic and provides client-side interaction between the page and users. It accesses the HTML through Document Object Model (DOM). It controls the new HTML features via their APIs.
There are modern web browsers in most desktop and mobile devices. These latest web techniques bring us the new game market—the HTML5 games. With the new power from these techniques, we can design games with HTML5 elements, CSS3 properties, and JavaScript to play in most browsers and mobile devices.
In this chapter, we will cover the following topics:
So, let's get started.
Discovering new features in HTML5
There are many new things introduced in HTML5 and CSS3. Before getting our hands dirty by creating the games, let's take an overview of the new features and see how we can use them to create games.
Canvas
Canvasis an HTML5 element that provides drawing shapes and bitmap manipulation functions in low levels. We can imagine the Canvas element as a dynamic image tag. The traditional <img> tag shows a static image. This image is usually static after it's loaded. We can change the <img> tag to another image source or apply styles to the image, but we cannot modify the image's bitmap context itself.
On the other hand, Canvas is like a client-side dynamic <img> tag. We can load images inside it, draw shapes there, and interact with it using JavaScript.
Canvas plays an important role in HTML5 game development. It is one of our main focus areas in this book.
Audio
Background music and sound effects are essential elements in game design. HTML5 comes with native audio support from the audio tag. Thanks to this feature, we do not require the proprietary Flash Player to play sound effects in our HTML5 games. However, there have been some restrictions on using Web Audio on the Web. We will discuss the usage of the audio tag in Chapter 6, Adding Sound Effects to Your Games.
Touch Events
Besides the traditional keyboard and mouse events, there are touch events that we can use to handle single and multi-touch events. We can design a game that works on mobile devices with touches. We can also handle gestures by observing the touch patterns.
GeoLocation
GeoLocation lets the web page retrieve the latitude and longitude of the user's computer. For example, Google's Ingress game makes use of GeoLocation to let players play the game in their real city. This feature may not have been so useful years ago when everyone was using the Internet with their desktop. There are not many things for which we need the accurate location of the road of the user. We can get the rough location by analyzing the IP address.
These days, more and more users are going on the Internet with their powerful smartphones. Webkit and other modern mobile browsers are in everyone's pocket. GeoLocation lets us design mobile applications and games to play with the inputs of a location.
WebGL
WebGL extends the Canvas element by providing a set of 3D graphics APIs in the web browser. The APIs follow the standard of OpenGL ES 2.0. WebGL provides a powerful GPG-accelerated, 3D rendering API for HTML5 games. Some 3D game engines support the export of WebGL, including the popular Unity engine. We can expect to see more HTML5 3D games waiting to be released using WebGL.
The techniques used to create games with WebGL are quite different than using Canvas. Creating games in WebGL requires handing the 3D models and using an API similar to OpenGL. Therefore, we will not discuss WebGL game development in this book.
WebGL has a better performance than 2D Canvas because of the GPU-rendering support. Some libraries allow a game to use Canvas 2D drawing API, and the tools render the canvas by drawing on WebGL to gain performance. Pixi.js (http://www.pixijs.com), EaselJS (http://blog.createjs.com/webgl-support-easeljs/) and WebGL-2D (https://github.com/corbanbrook/webgl-2d) are several such tools among them.
WebSocket
WebSocket is part of the HTML5 spec to connect the web page to a socket server. It provides us with a persistent connection between the browser and server. This means that the client does not need to poll the server for new data within short periods. The server will push updates to the browsers whenever there is any data to update. One benefit of this feature is that game players can interact with each other in almost real time. When one player does something and sends data to the server, we can send the individual player the update to create one-on-one real-time page play, or we can iterate all the connections in the server to send an event to every other connected browser to acknowledge what the player just did. This creates the possibility of building multiplayer HTML5 games.
Local storage
HTML5 provides a persistent data storage solution to web browsers.
Local Storage stores key-value pair data persistently. The data is still there after the browser terminates. Moreover, the data is not limited to be accessible only to the browsers that created it. It is available to all browser instances with the same domain. Thanks to Local Storage, we can easily save a game's status, such as progress and earned achievements, locally in web browsers.
Another database on web browser is IndexedDB. It's key-value pair too, but it allows storing objects and querying data with condition.
Offline applications
Normally, we need an Internet connection to browse web pages. Sometimes, we can browse cached offline web pages. These cached offline web pages usually expire quickly. With the next offline application introduced by HTML5, we can declare our cache manifest. This is a list of files that will be stored for later access when there is no Internet connection.
With the cache manifest, we can store all the game graphics, game control JavaScript files, CSS stylesheets, and the HTML files locally. We can also pack our HTML5 games as offline games on the desktop or mobile devices. Players can play the games even in the airplane mode. The following screenshot from the Pie Guy game (http://mrgan.com/pieguy) shows an HTML5 game being played on an iPhone without an Internet connection; note the little airplane symbol indicating the offline status:
Discovering new features in CSS3
CSS is the presentation layer and HTML is the content layer. It defines how the HTML looks. We cannot miss CSS when we create games with HTML5, especially DOM-based games. We may purely use JavaScript to create and style the games with a Canvas element. However, we need CSS when we create DOM-based HTML5 games. Therefore, let's take a look at what is new in CSS3 and how we can use the new properties to create games.
Instead of directly drawing and interacting on Canvas' drawing board, new CSS3 properties let us animate the DOM in different ways. This makes it possible to make more complicated DOM-based browser games.
CSS3 transition
Traditionally, the style changes immediately when we apply a new style to an element. CSS3 transition renders in-between styles during the style changes of the target elements over duration. For example, here, we have a blue box and want to change it to dark blue when we do a mouseover. We can do this by using the following code snippets:
HTML:
CSS:
The box changes to dark blue immediately when we do a mouseover. With CSS3 transition applied, we can tween the styles for a specific duration and easing value:
Tip
Downloading the example code
For all the Packt Publishing books you have purchased, you can download the example code files from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.
In the past, we needed JavaScript to calculate and render the in-between styles; this is much slower than using CSS3 transition because the browser natively makes the effects happen.
Note
Since some CSS3 specifications are still in the draft stage and not yet fixed, implementation from different browser vendors may have some minor differences to the W3C spec. Therefore, browser vendors tend to implement their CSS3 properties with a vendor prefix to prevent conflict.
Safari uses the -webkit- prefix. Opera uses the -o- prefix. Firefox uses the -moz- prefix and IE uses the -ms- prefix. Chrome used to use -webkit-, but now it doesn't use any prefix after switching its engine to Blink. It is a little complex now to declare a CSS3 property, such as flex, with several lines of the same rule for several browsers. We can expect the prefix to be dropped after the property spec is fixed.
In order to make the code cleaner in this book, I will use non-vendor prefix for all the properties in this book. I recommend you to use JavaScript-based libraries to automatically add the required vendor prefix for different web browsers. The prefix-free library (http://leaverou.github.io/prefixfree/) is one of them.
Alternatively, if you are using preprocessors, the compilation process may also add the necessary vendor prefix for you.
CSS3 transform
CSS3 transform lets us scale the elements, rotate them, and translate their position. CSS3 transform is divided into 2D and 3D. By combining the transform origin and 3D rotation and translation, we can animate 2D graphics in a 3D space.
CSS3 animation
CSS3 transition is one type of animation. It declares the tweening animation between two styles of the elements.
CSS3 animation is one step further in animation. We can define key frames of an animation. Each key frame contains a set of properties that should change at any particular moment. It is like a set of CSS3 transitions that are applied in sequence to the target element.
The AT-AT Walker (http://anthonycalzadilla.com/css3-ATAT/index-bones.html) shows a nice demo on creating a skeleton bone animation with CSS3 animation key frames, transform, and transition. This is shown in the following diagram:
The benefit of creating HTML5 games
We have explored several new key features from HTML5 and CSS3. With these features, we can create HTML5 games on browsers. But why do we need to do that? What is the benefit of creating HTML5 games?
Free and open standards
The web standards are open and free for use. In contrast, third-party tools are usually proprietary and they cost money. With proprietary technologies, the support from them may drop because of changes to the company's focus. The standardization and openness of HTML5 ensures that we will have browsers that support it.
Support for multiple platforms
With the built-in support of all the HTML5 features in modern browsers, we do not require the users to preinstall any third-party plugin in order to play any file. These plugins are not standard. They usually require an extra plugin installation that you may not be able to install. For instance, millions of Apple iOS devices around the world do not support third-party plugins, such as Flash Player, in their mobile Safari. Despite whatever the reason might be, Apple does not allow Flash Player to run on their Mobile Safaris, instead, HTML5 and the related web standard are what they get in their browsers. We can reach this user base by creating HTML5 games that are optimized for mobiles.
Native app-rendering performance in particular scenarios
When we code the game in a Canvas, there are some rendering engines that can translate our Canvas drawing code into OpenGL, thus rendering in native mobile device. This means that while we are still coding the game for a web browser, our game can gain benefits in mobile devices by the native app OpenGL rendering. Ejecta (http://impactjs.com/ejecta) and CocoonJS (http://ludei.com/cocoonjs) are two such engines.
Breaking the boundary of usual browser games
In traditional game designing, we build games within a boundary box. We play video games on a television. We play Flash games in web browsers with a rectangle boundary.
Using creativity, we are not bound in a rectangle game stage any more. We can have fun with all the page elements.
Twitch (http://reas.com/twitch/) is a game from Chrome Experiments. It is a collection of mini games where the player has to carry the ball from the starting point to the end point. The fun part is that each mini game is a small browser window. When the ball reaches the destination point of that mini game, it is transferred into the newly created mini game browser to continue the journey. The following screenshot shows the whole map of Twitch with the individual web browsers:
Building HTML5 games
Thanks to the new features of HTML5 and CSS3, we can now create an entire game in the browser. We can control every element in the DOM. We can animate each document object with CSS3. We have Canvas to dynamically draw things and interact with them. We have an audio element to handle the background music and sound effects. We also have Local Storage to save game data, and WebSocket to create a real-time multiplayer game. Most modern browsers are already supporting these features. It is now time to build HTML5 games.
What others are playing with HTML5
This is a good opportunity to study how different HTML5 games perform by watching other HTML5 games that are made with different techniques.
Coca-Cola's Ahh campaign
Coca-Cola had run a campaign known as Ahh (http://ahh.com) with lots of interactive mini games. The interactions combined several techniques that included canvas and device rotation. Most of them work well in both desktop and mobile devices.
Asteroid-styled bookmarklet
Erik, a web designer from Sweden, created an interesting bookmarklet. This
