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

Simulating a spotlight

The fixed function pipeline had the ability to define light sources as spotlights. In such a configuration, the light source was considered to be one that only radiated light within a cone, the apex of which was located at the light source. Additionally, the light was attenuated so that it was maximal along the axis of the cone and decreased towards the outside edges. This allowed us to create light sources that had a similar visual effect to a real spotlight.

The following figure shows a teapot and a torus rendered with a single spotlight. Note the slight decrease in the intensity of the spotlight from the center towards the outside edge.

In this recipe, we'll use a shader to implement a spotlight effect similar to that produced by the fixed-function pipeline.

The spotlight's cone is defined by a spotlight direction (d in the preceding figure), a cutoff angle (c in the preceding figure), and a position (P in the preceding figure). The intensity of the spotlight is considered...