Overview

Computer graphics has come a long way from the early days of line drawings and light pens. Today anyone can run interactive and realistic graphics applications on the hardware available on an affordable personal computer. While hardware progress has been impressive, widespread gains in software expertise has been more elusive. There are many computer graphics professionals and enthusiasts out there, but a comprehensive understanding of the accelerated graphics pipeline and how to exploit it is less widespread.

This book attempts to bring the computer graphics enthusiast, whether professional or amateur, beyond the basics covered in computer graphics texts, and introduce them to a mix of more intense practical and theoretical discussion that is hard to obtain outside of a professional computer graphics environment.

We emphasize the algorithmic side of computer graphics, with a practical application focus. We try to strike a balance between useful examples and approachable theory. We present usable techniques for real world problems, but support them with enough theory and background so the reader can extend and modify the ideas presented here.

This book is about graphics techniques, techniques that don’t require esoteric hardware or custom graphics libraries, that are written in a comprehensible style, and do useful things. This book will teach you some graphics, especially areas that are sometimes underrepresented in graphics texts. But it also goes further, showing you how to apply those techniques in real world applications, filling real world needs.

Since there are already a number of excellent books that provide an introduction to computer graphics (Foley, 1994; Watt, 1989; Rogers, 1997; Angel, 1997; Newman, 1973) and to OpenGL programming (Neider, 1997; Angel, 1997) we have been necessarily brief in these areas. We assume that the reader is comfortable with these fundamentals; however, we have included extra introductory material where we thought it would improve understanding of later sections.

We also note that the computer graphics field has a lot of competing notation and vocabulary. We have tried to be consistent with terminology and notation used in the OpenGL specification and the “standard” OpenGL books while at the same time providing some mention of alternative terminology when it is relevent.

OpenGL

We chose OpenGL as our base graphics language for a number of reasons. It is designed to be full featured, to run efficiently on a wide range of graphics architectures, and is clean and straightforward to use. It also dictates very little policy. It is easy to mix and match graphics features in OpenGL to get new effects that may not have even been considered when the language was designed. Its clear specification gives the application programmer confidence that applications written in OpenGL will act predictably on many different graphics hardware and driver implementations.

OpenGL is also widely available. It can be obtained for free on all the important architectures today: Apple Machintosh, all flavors of Microsoft Windows, nearly all Unix variants including Linux, and OS/2. Most commercial system and graphics hardware vendors support OpenGL as well, and support for hardware accelerated implementations has grown rapidly, especially in the personal computer space. OpenGL runs on a wide range of graphics hardware; from “big iron” compute clusters, to OpenGL ES, which is designed to provide 3D graphics on embedded devices as small as a cell phone.

Given the broad applicability, scalability, and wide availability, OpenGL is an easy choice as the basis for describing graphics algorithms. However, even if you don’t use OpenGL, the graphics APIs in common use are conceptually similar enough that you will still find this book useful. OpenGL remains an evolving specification. Throughout the book we make references to various revisions of the specification (versions 1.0–1.5) and discuss both OpenGL architecture review board (ARB) extensions and various vendor-specific extensions when we believe they enhance the discussion of a particular subject. Rather than focus on the feature set of the most advanced versions of OpenGL, we have included a broad range of algorithms with varying requirements. For many techniques we describe algorithm variations that cover a range of earlier and more advanced versions of OpenGL. We have followed this path since a wide range of OpenGL versions are deployed across various environments including the burgeoning embedded space.

Book Organization

This book is divided into three parts. We start with a conceptual overview of computer graphics, emphasizing areas important to the techniques in this book, with extra attention in some overlooked areas. Hand in hand with our introduction to computer graphics, we’ll describe the OpenGL pipeline, with extra detail on the parts of the pipeline most techniques rely on heavily: lighting, texture mapping, rasterization, and depth buffering. We also use this opportunity to describe OpenGL system deployment, including the platform embedding layer and an overview of common hardware acceleration techniques for the pipeline.

With this foundation in place, Part II introduces a set of important basic techniques. Useful by themselves, they help re-enforce the insights gleaned from the overview. These sequences are also used as building blocks for more complex and sophisticated techniques. To help tie them more tightly to the graphics concepts described in the previous part, these techniques are presented and organized with respect to the OpenGL architecture.

The third and final part covers more sophisticated and complex techniques. These techniques are categorized into application areas to help organize the material. The start of each application section has an introduction to the problems and issues important for that area, making these sections more interesting and useful to readers not well versed in that particular field.

The book is heavily cross-referenced. Complex techniques reference the simple ones they build upon, and both levels of technique reference the conceptual overview. This allows the reader to use the book as a self-guided tutorial, learning more about techniques and concepts of interest in greater depth.

Example Code

To avoid cluttering the text with large fragments of example code, code fragments are used sparingly. Algorithms are usually described as a sequence of steps. However, since details are often the difference between a working program and a black screen, we have tried to include full blown example programs for most algorithms. This example code is available for internet download from www.mkp.com/opengl.

Conventions

We use conventions and terminology similar to that found in the OpenGL specification and in the “red-blue-green-white” series of OpenGL books. In addition, we use the following conventions: