Book Image

GLSL Essentials

By : Jacobo Rodriguez
Book Image

GLSL Essentials

By: Jacobo Rodriguez

Overview of this book

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.
Table of Contents (13 chapters)

Language basics

Before we begin, I expect you to have a basic understanding and proficiency of C. OpenGL is available in different programming languages such as Java, Python, or C#. However, I will be concentrating on the C/GLSL concepts.


The instructions always end with a semicolon, and there could be more than one per line:

c = cross(a, b);
vec4 g; g = vec4(1, 0, 1, 1);

A block of instructions is created by putting them in brackets. All variables declared inside a block will be destroyed when the block finishes. If two variables have the same name—one declared outside the block (also called scope) and another declared inside the block—by default, the inner variable is the one which will be referenced:

float a = 1.0;
float b = 2.0;
  float a = 4.0;
  float c = a + 1.0; // c -> 4.0 + 1.0
b = b + c; // wrong statement. Variable c does not exist here

Tabulations or whitespaces don't change the semantics of the language. You can use them to format the code at your wish.

Basic types...