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 a cartoon shading effect


Toon shading (also called cel shading) is a non-photorealistic rendering technique that is intended to mimic the style of shading often used in hand-drawn animation. There are many different techniques that are used to produce this effect. In this recipe, we'll use a very simple technique that involves a slight modification to the ambient and diffuse shading model.

The basic effect is to have large areas of constant color with sharp transitions between them. This simulates the way that an artist might shade an object using strokes of a pen or brush. The following image shows an example of a teapot and torus rendered with toon shading:

The technique presented here involves computing only the ambient and diffuse components of the typical ADS shading model, and quantizing the cosine term of the diffuse component. In other words, the value of the dot product normally used in the diffuse term is restricted to a fixed number of possible values. The following table...