Book Image

OpenGL 4 Shading Language Cookbook - Third Edition

By : David Wolff
Book Image

OpenGL 4 Shading Language Cookbook - Third Edition

By: David Wolff

Overview of this book

OpenGL 4 Shading Language Cookbook, Third Edition provides easy-to-follow recipes that first walk you through the theory and background behind each technique, and then proceed to showcase and explain the GLSL and OpenGL code needed to implement them. The book begins by familiarizing you with beginner-level topics such as compiling and linking shader programs, saving and loading shader binaries (including SPIR-V), and using an OpenGL function loader library. We then proceed to cover basic lighting and shading effects. After that, you'll learn to use textures, produce shadows, and use geometry and tessellation shaders. Topics such as particle systems, screen-space ambient occlusion, deferred rendering, depth-based tessellation, and physically based rendering will help you tackle advanced topics. OpenGL 4 Shading Language Cookbook, Third Edition also covers advanced topics such as shadow techniques (including the two of the most common techniques: shadow maps and shadow volumes). You will learn how to use noise in shaders and how to use compute shaders. The book provides examples of modern shading techniques that can be used as a starting point for programmers to expand upon to produce modern, interactive, 3D computer-graphics applications.
Table of Contents (17 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Creating shadows using shadow volumes and the geometry shader


As we discovered in the previous recipes, one of the main problems with shadow maps is aliasing. The problem essentially boils down to the fact that we are sampling the shadow map(s) at a different frequency (resolution) than we are using when rendering the scene. To minimize the aliasing we can blur the shadow edges (as in the previous recipes), or try to sample the shadow map at a frequency that is closer to the corresponding resolution in projected screen space. There are many techniques that help with the latter; for more details, I recommend the book Real-Time Shadows.

An alternate technique for shadow generation is called shadow volumes. The shadow volume method completely avoids the aliasing problem that plagues shadow maps. With shadow volumes, you get pixel-perfect hard shadows, without the aliasing artifacts of shadow maps. The following image shows a scene with shadows that are produced using the shadow volume technique...