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 5. Geometry Shaders

Up until now, we've learnt the basic configuration of the pipeline and how to produce a render using a soup of triangles and textures. In this chapter, we will add a new shader type to our knowledge set. It will serve to improve our scenes, giving them more flexibility by letting us interact more deeply with the pipeline, but without having to increase the CPU side code or the bandwidth between the CPU and the GPU.

In this chapter, we will learn how these new shaders work and cover a few examples of techniques where geometry shaders could give us great flexibility. We will cover the following topics:

  • How to replicate geometry on the fly, for example, to make twin models

  • How to make a particle or crowd system with complex-shaped particles parting from bare points