Book Image

OpenGL 4.0 Shading Language Cookbook

Book Image

OpenGL 4.0 Shading Language Cookbook

Overview of this book

The 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 4.0, the language has been further refined to provide programmers with greater flexibility, and additional features have been added such as an entirely new stage called the tessellation shader. The OpenGL Shading Language 4.0 Cookbook provides easy-to-follow examples that first walk you through the theory and background behind each technique then go on to provide and explain the GLSL and OpenGL code needed to implement it. Beginning level through to advanced techniques are presented including topics such as texturing, screen-space techniques, lighting, shading, tessellation shaders, geometry shaders, and shadows. The OpenGL Shading Language 4.0 Cookbook is a practical guide that takes you from the basics of programming with GLSL 4.0 and OpenGL 4.0, through basic lighting and shading techniques, to more advanced techniques and effects. It presents techniques for producing basic lighting and shading effects; 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, shadowing, tessellation and geometry shaders, noise, and animation. The OpenGL Shading Language 4.0 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 (16 chapters)
OpenGL 4.0 Shading Language Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Using gamma correction to improve image quality


It is common for many books about OpenGL and 3D graphics to somewhat neglect the subject of gamma correction. Lighting and shading calculations are performed, and the results are sent directly to the output buffer without modification. However, when we do this, we may produce results that don't quite end up looking the way we might expect they should. This may be due to the fact that computer monitors (both the old CRT and the newer LCD) have a non-linear response to pixel intensity. For example, without gamma correction, a grayscale value of 0.5 will not appear half as bright as a value of 1.0. Instead, it will appear to be darker than it should.

The lower curve in the following graph shows the response curves of a typical monitor (gamma of 2.2). The x axis is the intensity, and the y axis is the perceived intensity. The dashed line represents a linear set of intensities. The upper curve represents gamma correction applied to linear values...