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

Tessellating based on depth


One of the greatest things about tessellation shaders is how easy it is to implement level-of-detail (LOD) algorithms. LOD is a general term in computer graphics that refers to the process of increasing/decreasing the complexity of an object's geometry with respect to the distance from the viewer (or other factors). As an object moves farther away from the camera, less geometric detail is needed to represent the shape because the overall size of the object becomes smaller. However, as the object moves closer to the camera, the object fills more and more of the screen, and more geometric detail is needed to maintain the desired appearance (smoothness or lack of other geometric artifacts).

The following figure shows a few teapots rendered with tessellation levels that depend on distance from the camera. Each teapot is rendered using exactly the same code on the OpenGL side. The TCS automatically varies the tessellation levels based on depth.

When tessellation shaders...