GLSL Essentials E-Book

Jacobo Rodriguez

• Herausgeber: Packt Publishing
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 118

Veröffentlichungsjahr: 2013

Beschreibung

Shader programming has been the largest revolution in graphics programming. OpenGL Shading Language (abbreviated: GLSL or GLslang), is a high-level shading language based on the syntax of the C programming language.With GLSL you can execute code on your GPU (aka graphics card). More sophisticated effects can be achieved with this technique.Therefore, knowing how OpenGL works and how each shader type interacts with each other, as well as how they are integrated into the system, is imperative for graphic programmers. This knowledge is crucial in order to be familiar with the mechanisms for rendering 3D objects.

GLSL Essentials is the only book on the market that teaches you about shaders from the very beginning. It shows you how graphics programming has evolved, in order to understand why you need each stage in the Graphics Rendering Pipeline, and how to manage it in a simple but concise way. This book explains how shaders work in a step-by-step manner, with an explanation of how they interact with the application assets at each stage.

This book will take you through the graphics pipeline and will describe each section in an interactive and clear way. You will learn how the OpenGL state machine works and all its relevant stages. Vertex shaders, fragment shaders, and geometry shaders will be covered, as well some use cases and an introduction to the math needed for lighting algorithms or transforms. Generic GPU programming (GPGPU) will also be covered.

After reading GLSL Essentials you will be ready to generate any rendering effect you need.

Leseprobe

Table of Contents

GLSL Essentials

Credits

About the Author

About the Reviewers

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Why Subscribe?

Free Access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the color images of this book

Errata

Piracy

Questions

1. The Graphics Rendering Pipeline

A brief history of graphics hardware

The Graphics Rendering Pipeline

Geometry stages (per-vertex operations)

Fragment stages (per-fragment operations)

External stages

Differences between fixed and programmable designs

Types of shaders

Vertex shaders

Fragment shaders

Geometry shaders

Compute shaders

GPU, a vectorial and parallel architecture

The shader environment

Summary

2. GLSL Basics

The Language

Language basics

Instructions

Basic types

Variable initializers

Vector and matrix operations

Castings and conversions

Code comments

Flow control

Loops

Structures

Arrays

Functions

Preprocessor

Shader input and output variables

Uniform variables

Other input variables

Shader output variables

Summary

3. Vertex Shaders

Vertex shader inputs

Vertex attributes

Uniform variables

Vertex shader outputs

Drawing a simple geometry sample

Distorting a geometry sample

Using interpolators

Simple lighting

Basic lighting theory

Lighting example code

Summary

4. Fragment Shaders

Execution model

Terminating a fragment shader

Inputs and outputs

Examples

Solid color mesh

Interpolated colored mesh

Using interpolators to compute the texture coordinates

Phong lighting

Summary

5. Geometry Shaders

Geometry shaders versus vertex shaders

Inputs and outputs

Interface blocks

Example – pass-thru shader

Example – using attributes in the interface blocks

A crowd of butterflies

Summary

6. Compute Shaders

Execution model

Render to texture example

Raw data computations

Summary

Index

GLSL Essentials

GLSL Essentials

Copyright © 2013 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: December 2013

Production Reference: 1181213

Published by Packt Publishing Ltd.

Livery Place

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Birmingham B3 2PB, UK.

ISBN 978-1-84969-800-9

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Cover Image by Jacobo Rodríguez Villar (<[email protected]>)

Credits

Author

Jacobo Rodríguez

Reviewers

Dimitrios Christopoulos

Toni Ascó González

Oscar Ripolles

Acquisition Editors

Antony Lowe

Rebecca Pedley

Commissioning Editors

Subho Gupta

Priyanka Shah

Sharvari Tawde

Technical Editors

Venu Manthena

Gaurav Thingalaya

Project Coordinator

Amey Sawant

Proofreaders

Maria Gould

Paul Hindle

Indexer

Priya Subramani

Graphics

Ronak Dhruv

Production Coordinator

Shantanu Zagade

Cover Work

Shantanu Zagade

About the Author

Jacobo Rodríguez is a real-time computer graphics programmer living in the north of Spain. He has working experience with computer graphics, digital photogrammetry, computer vision, and video game development. Jacobo has worked for cutting-edge technology companies such as Metria Digital and Blit Software, and has also worked as an entrepreneur and freelancer for a variety of clients of platforms such as PC, iOS, PlayStation 3, PlayStation Vita, and PlayStation Portable. Jacobo has been working and learning at the same time for the last 20 years in the computer graphics field in roles ranging from junior programmer to project manager, passing through R&D director as well. Jacobo has always been very committed to the computer graphics community, having released for free the OpenGL Shader Designer: the first application in the world (even before NVIDIA with FX Composer or ATI with RenderMonkey) designed to visually develop and program GLSL shaders, as well as some OpenGL programming tutorials, all forming part of the Official OpenGL SDK.

I would like to thank my family for supporting me in those late nights and weekend writing sessions. I would also like to thank Toni Ascó Emilio, José Dominguez, and Iñaki Griego, for their invaluable support and resources during the production of this book.

About the Reviewers

Dimitrios Christopoulos studied Computer Engineering and Informatics and holds a Master of Science degree in Virtual Reality and Computer Graphics. He has 16+ years of experience in 3D computer graphics with a strong specialty in C/C++/OpenGL and Linux. Dimi has worked for European Union research projects, Indie game productions, and museums producing games, educational applications, and cultural heritage productions for desktops and virtual reality installations such as Domes, Caves, Reality Centers, and Powerwalls. His research interests include virtual reality, human computer interaction, computer graphics, and games, with numerous publications in relevant conferences and journals. Dimitrios has been an author of the book More OpenGL Programming, Course Technology PTR, and has contributed to OpenGL Programming, Prima Tech, and has been a reviewer for OpenGL Development Cookbook, Packt Publishing.

I would like to thank my wife Giota for being supportive during my late night reviewing sessions.

Toni Ascó González holds a Master's degree in Computer Science specializing in real-time graphics and OpenGL. For the past 16 years, he has been programming graphics applications from virtual reality to video games. He founded a virtual reality company in Barcelona, and dedicated eight years to develop a state-of-the-art, real-time software for architectural visualization. After that experience, he moved to Bravo Game Studios and developed video games for mobile platforms and portable consoles. Currently, he applies his experience in 3D and real-time graphics in the virtual gambling field.

I would like to thank my other half, Chu, for her patience, love, and care. Life would be uninteresting and void without you at my side. Of course, thanks to my mother and my brother for being my foundation and supporting my love for computers since I was nine. 
I would also like to thank all of the mentors and colleagues who have been with me over all these years. Bernat Muñoz, Alex Novell, and Marc Martí from Insideo for all those wonderful years experimenting with new techniques. Also, Alberto García-Baquero, Benjamín de la Fuente, and Miguel Guillén, who have shown me new and amazing ways of doing things, and given me new perspectives on product development. Finally, a special mention to Jacobo Rodriguez Villar; without him, I wouldn't be where I am.

Oscar Ripolles received his degree in Computer Engineering in 2004 and his Ph.D. in 2009 at the Universitat Jaume I in Castellon (Spain). He has also been a researcher at the Université de Limoges (France) and at the Universidad Politecnica de Valencia (Spain). He is currently woking in neuroimaging at Neuroelectrics in Barcelona (Spain). His research interests include multiresolution modeling, geometry optimization, hardware programming, and medical imaging.

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Preface

If you are still in the old fixed pipeline days and your OpenGL knowledge is a little bit rusty, or if you want to jump from OpenGL|ES to a more complete and modern version of OpenGL, then this book is for you. Inside the pages of this book, you will find the details of the most recent OpenGL Shading Language Version: 4.3.

This book has been written looking forward in the OpenGL specification. No old functionalities or deprecated code will be found in this book, just the plain 4.3 Version.

What this book covers

Chapter 1, The Graphics Rendering Pipeline, starts with a brief introduction to the rendering pipeline and moves on to give an overview of the programmable stages.

Chapter 2, GLSL Basics, covers language basics, types, vector operations, flow control, preprocessor, and shader inputs and outputs.

Chapter 3, Vertex Shaders, looks at the vertex programmable stage, uniform variables and basic lighting, and vertex shader examples.

Chapter 4, Fragment Shaders, looks at the execution model, inputs and outputs, and examples.

Chapter 5, Geometry Shaders, looks at geometry shader structure, interface blocks, and examples.

Chapter 6, Compute Shaders, covers the execution model, GPGPU basics, render to texture, and basic raw computations.

What you need for this book

In order to run the samples from this book, you will need a text editor and a C/C++ compiler. For the text editor, a free editor such as Notepad++ or SciTE could be used, and for the C/C++ compiler, GCC/G++, or Visual Studio (the Express version is free) are the best choices. As we are addressing the latest OpenGL version, a graphics card that supports at least OpenGL 4.3 will be needed.

Who this book is for

This book is for people who have some experience or basic knowledge in computer graphics and who want to upgrade their knowledge to the latest OpenGL version. It is also for people who want to take the jump from the fixed pipeline to the programmable pipeline.

Reader feedback

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Downloading the color images of this book

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Errata

Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you would report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting http://www.packtpub.com/submit-errata, selecting your book, clicking on the errata submission form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded on our website, or added to any list of existing errata, under the Errata section of that title. Any existing errata can be viewed by selecting your title from http://www.packtpub.com/support.

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Questions

You can contact us at <[email protected]> if you are having a problem with any aspect of the book, and we will do our best to address it.

Chapter 1. The Graphics Rendering Pipeline

If this is your first approach to shader technology, you should know a few things before we start writing GLSL code. The differences between the usual CPU architecture and a GPU are big enough to warrant mentioning them.