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

Anti-aliasing shadow edges with PCF


One of the simplest and most common techniques for dealing with the aliasing of shadow edges is called percentage-closer filtering (PCF). The name comes from the concept of sampling the area around the fragment and determining the percentage of the area that is closer to the light source (in shadow). The percentage is then used to scale the amount of shading (diffuse and specular) that the fragment receives. The overall effect is a blurring of the shadow's edges.

The basic technique was first published by Reeves et al. in a 1987 paper (SIGGRAPH Proceedings, Volume 21, Number 4, July 1987). The concept involves transforming the fragment's extents into shadow space, sampling several locations within that region, and computing the percent that is closer than the depth of the fragment. The result is then used to attenuate the shading. If the size of this filter region is increased, it can have the effect of blurring the shadow's edges.

A common variant of the...