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 noise texture using GLM


To create a texture for use as a source of noise, we need some way to generate noise values. Implementing a proper noise generator from scratch can be a fairly daunting task. Luckily, GLM provides some functions for noise generation that are straightforward and easy to use.

In this recipe, we'll use GLM to generate a 2D texture of noise values created using a Perlin noise generator. GLM can generate 2D, 3D, and 4D Perlin noise via the glm::perlin function.

It is a common practice to use Perlin noise by summing the values of the noise function with increasing frequencies and decreasing amplitudes. Each frequency is commonly referred to as an octave (double the frequency). For example, in the following image, we show the results of the 2D Perlin noise function sampled at four different octaves. The sampling frequencies increase from left to right.

The leftmost image in the following image is the function sampled at our base frequency, and each image to the right...