Book Image

OpenGL 4 Shading Language Cookbook - Second Edition

By : David Wolff
Book Image

OpenGL 4 Shading Language Cookbook - Second Edition

By: David Wolff

Overview of this book

OpenGL Shading Language (GLSL) is a programming language used for customizing parts of the OpenGL graphics pipeline that were formerly fixed-function, and are executed directly on the GPU. It provides programmers with unprecedented flexibility for implementing effects and optimizations utilizing the power of modern GPUs. With Version 4, the language has been further refined to provide programmers with greater power and flexibility, with new stages such as tessellation and compute. OpenGL 4 Shading Language Cookbook provides easy-to-follow examples that first walk you through the theory and background behind each technique, and then go on to provide and explain the GLSL and OpenGL code needed to implement it. Beginner level through to advanced techniques are presented including topics such as texturing, screen-space techniques, lighting, shading, tessellation shaders, geometry shaders, compute shaders, and shadows. OpenGL Shading Language 4 Cookbook is a practical guide that takes you from the fundamentals of programming with modern GLSL and OpenGL, through to advanced techniques. The recipes build upon each other and take you quickly from novice to advanced level code. You'll see essential lighting and shading techniques; examples that demonstrate how to make use of textures for a wide variety of effects and as part of other techniques; examples of screen-space techniques including HDR rendering, bloom, and blur; shadowing techniques; tessellation, geometry, and compute shaders; how to use noise effectively; and animation with particle systems. OpenGL Shading Language 4 Cookbook 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)
OpenGL 4 Shading Language Cookbook Second Edition
About the Author
About the Reviewers

Creating a seamless noise texture

It can be particularly useful to have a noise texture that tiles well. If we simply create a noise texture as a finite slice of noise values, then the values will not wrap smoothly across the boundaries of the texture. This can cause hard edges (seams) to appear in the rendered surface if the texture coordinates extend outside of the range of zero to one.

Fortunately, GLM provides a periodic variant of Perlin noise that can be used to create a seamless noise texture.

The following image shows an example of regular (left) and periodic (right) 4-octave Perlin noise. Note that in the left image, the seams are clearly visible, while they are hidden in the right image.

In this example, we'll modify the code from the previous recipe to produce a seamless noise texture.

Getting ready

For this recipe, we'll start with the code from the previous recipe, Creating a noise texture using GLM.

How to do it...

Modify the code from the previous recipe in the following way.