Preface

WebGL is a new web technology that brings hardware-accelerated 3D graphics to the browser without requiring the user to install additional software. As WebGL is based on OpenGL and brings in a new concept of 3D graphics programming to web development, it may seem unfamiliar to even experienced web developers.

Packed with many examples, this book shows how WebGL can be easy to learn despite its unfriendly appearance. Each chapter addresses one of the important aspects of 3D graphics programming and presents different alternatives for its implementation. The topics are always associated with exercises that will allow the reader to put the concepts to the test in an immediate manner.

WebGL Beginner's Guide presents a clear road map to learning WebGL. Each chapter starts with a summary of the learning goals for the chapter, followed by a detailed description of each topic. The book offers example-rich, up-to-date introductions to a wide range of essential WebGL topics, including drawing, color, texture, transformations, framebuffers, light, surfaces, geometry, and more. Each chapter is packed with useful and practical examples that demonstrate the implementation of these topics in a WebGL scene. With each chapter, you will "level up" your 3D graphics programming skills. This book will become your trustworthy companion filled with the information required to develop cool-looking 3D web applications with WebGL and JavaScript.

What this book covers

Chapter 1, Getting Started with WebGL, introduces the HTML5 canvas element and describes how to obtain a WebGL context for it. After that, it discusses the basic structure of a WebGL application. The virtual car showroom application is presented as a demo of the capabilities of WebGL. This application also showcases the different components of a WebGL application.

Chapter 2, Rendering Geometry, presents the WebGL API to define, process, and render objects. Also, this chapter shows how to perform asynchronous geometry loading using AJAX and JSON.

Chapter 3, Lights!, introduces ESSL the shading language for WebGL. This chapter shows how to implement a lighting strategy for the WebGL scene using ESSL shaders. The theory behind shading and reflective lighting models is covered and it is put into practice through several examples.

Chapter 4, Camera, illustrates the use of matrix algebra to create and operate cameras in WebGL. The Perspective and Normal matrices that are used in a WebGL scene are also described here. The chapter also shows how to pass these matrices to ESSL shaders so they can be applied to every vertex. The chapter contains several examples that show how to set up a camera in WebGL.

Chapter 5, Action, extends the use of matrices to perform geometrical transformations (move, rotate, scale) on scene elements. In this chapter the concept of matrix stacks is discussed. It is shown how to maintain isolated transformations for every object in the scene using matrix stacks. Also, the chapter describes several animation techniques using matrix stacks and JavaScript timers. Each technique is exemplified through a practical demo.

Chapter 6, Colors, Depth Testing, and Alpha Blending, goes in depth about the use of colors in ESSL shaders. This chapter shows how to define and operate with more than one light source in a WebGL scene. It also explains the concepts of Depth Testing and Alpha Blending, and it shows how these features can be used to create translucent objects. The chapter contains several practical exercises that put into practice these concepts.

Chapter 7, Textures, shows how to create, manage, and map textures in a WebGL scene. The concepts of texture coordinates and texture mapping are presented here. This chapter discusses different mapping techniques that are presented through practical examples. The chapter also shows how to use multiple textures and cube maps.

Chapter 8, Picking, describes a simple implementation of picking which is the technical term that describes the selection and interaction of the user with objects in the scene. The method described in this chapter calculates mouse-click coordinates and determines if the user is clicking on any of the objects being rendered in the canvas. The architecture of the solution is presented with several callback hooks that can be used to implement logic-specific application. A couple of examples of picking are given.

Chapter 9, Putting It All Together, ties in the concepts discussed throughout the book. In this chapter the architecture of the demos is reviewed and the virtual car showroom application outlined in Chapter 1, Getting Started with WebGL, is revisited and expanded. Using the virtual car showroom as the case study, this chapter shows how to import Blender models into WebGL scenes and how to create ESSL shaders that support the materials used in Blender.

Chapter 10, Advanced Techniques, shows a sample of some advanced techniques such as post-processing effects, point sprites, normal mapping, and ray tracing. Each technique is provided with a practical example. After reading this WebGL Beginner's Guide you will be able to take on more advanced techniques on your own.

What you need for this book

• You need a browser that implements WebGL. WebGL is supported by all major browser vendors with the exception of Microsoft Internet Explorer. An updated list of WebGL-enabled browsers can be found here:

  http://www.khronos.org/webgl/wiki/Getting_a_WebGL_Implementation

• A source code editor that recognizes and highlights JavaScript syntax.

• You may need a web server such as Apache or Lighttpd to load remote geometry if you want to do so (as shown in Chapter 2, Rendering Geometry). This is optional.

Who this book is for

This book is written for JavaScript developers who are interested in 3D web development. A basic understanding of the DOM object model, the JQuery library, AJAX, and JSON is ideal but not required. No prior WebGL knowledge is expected.

A basic understanding of linear algebra operations is assumed.

Conventions

In this book, you will find several headings appearing frequently.

To give clear instructions of how to complete a procedure or task, we use:

Time for action – heading

1. Action 1

2. Action 2

3. Action 3

Instructions often need some extra explanation so that they make sense, so they are followed with:

What just happened?

This heading explains the working of tasks or instructions that you have just completed.

You will also find some other learning aids in the book, including:

Have a go hero – heading

These set practical challenges and give you ideas for experimenting with what you have learned.

You will also find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text are shown as follows: "Open the file ch1_Canvas.html using one of the supported browsers."

A block of code is set as follows:

<!DOCTYPE html>
<html>
<head>
   <title> WebGL Beginner's Guide - Setting up the canvas </title>
   <style type="text/css">
   canvas {border: 2px dotted blue;}
   </style>
</head>
<body>
<canvas id="canvas-element-id" width="800" height="600">
Your browser does not support HTML5
</canvas>
</body>
</html>

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

<!DOCTYPE html>
<html>
<head>
   <title> WebGL Beginner's Guide - Setting up the canvas </title>
   <style type="text/css">
   canvas {border: 2px dotted blue;}
   </style>
</head>
<body>
<canvas id="canvas-element-id" width="800" height="600">
Your browser does not support HTML5
</canvas>
</body>
</html>

Any command-line input or output is written as follows:

--allow-file-access-from-files

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Now switch to camera coordinates by clicking on the Camera button."

Note

Warnings or important notes appear in a box like this.

Note

Tips and tricks appear like this.

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