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
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Creating a bloom effect


A bloom is a visual effect where the bright parts of an image seem to have fringes that extend beyond the boundaries into the darker parts of the image. This effect has its basis in the way that cameras and the human visual system perceive areas of high contrast. Sources of bright light "bleed" into other areas of the image due to the so-called Airy disc, which is a diffraction pattern produced by light that passes through an aperture.

The following image shows a bloom effect in the animated film Elephant's Dream (© 2006, Blender Foundation / Netherlands Media Art Institute / www.elephantsdream.org). The bright white color from the light behind the door "bleeds" into the darker parts of the image.

Producing such an effect within an artificial CG rendering requires determining which parts of the image are bright enough, extracting those parts, blurring, and re-combining with the original image. Typically, the bloom effect is associated with HDR (High Dynamic Range) rendering...