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)

Chapter 3. Vertex Shaders

Vertex shaders are responsible for transforming the incoming geometry into something suitable to be rasterized, according to the rendering pipeline laws. In order to make this work, a vertex shader's inputs and outputs must be very well defined.

In this chapter we will see how the inputs must be prepared and how we can compute the outputs. Also, we will talk extensively about the operations we are allowed to perform.

A vertex shader executes once and only once for each vertex sent to the GPU. Inside a vertex shader, you have access to all information about that vertex, but you can't access the other sibling vertices of the primitive that is being processed.

It doesn't matter for the vertex shader which type of primitive and how you had arranged it before sending it to the GPU (indexed, non-indexed, interleaved, non-interleaved, VBO, VAO, and so on).

So, in the end, a vertex shader is a "give me one vertex that I'll transform for you" machine, and nothing else. Things...