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)

Shader input and output variables

Until now, we've been speaking about the language itself; how it's similar to the C programming language, but focusing specially on the differences. That was only the language part. Now it's time to see some of the functional parts of GLSL and cover an important topic: the inputs and outputs of the shaders.

Uniform variables

Suppose, you want to create a shader that makes use of a simple light. Well, shaders don't know about lights or any other high-level concept. Shaders only know about math and programming. So, if the language doesn't have support for lights, how would I use the light's position or color in a shader?

You need to pass those variables from your application to your shader and perform the lighting calculations inside the shader.

A parameter that is passed from the application to the shaders is called a uniform variable. Those variables are always read-only (constant), global to the shaders that form the current executable program.

The procedure...