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

The Blinn-Phong reflection model


As covered in the Implementing the Phong reflection model recipe in Chapter 3, The Basics of GLSL Shaders, the specular term in the equation involves the dot product of the vector of pure reflection (r), and the direction toward the viewer (v):

In order to evaluate the preceding equation, we need to find the vector of pure reflection (r), which is the reflection of the vector toward the light source (s) about the normal vector (n):

Note

This equation is implemented using the GLSL function reflect.

We can avoid calculating r by making use of the following observation. When v is aligned with r, the normal vector (n) must be halfway between v and s. Let's define the halfway vector (h) as the vector that is halfway between v and s, where h is normalized after the addition:

The following diagram shows the relative positions of the halfway vector and the others:

We can then replace the dot product in the equation for the specular component, with the dot product of h...