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

Shading with multiple positional lights


When shading with multiple light sources, we need to evaluate the shading equation for each light and sum the results to determine the total light intensity reflected by a surface location. The natural choice is to create uniform arrays to store the position and intensity of each light. We'll use an array of structures so that we can store the values for multiple lights within a single uniform variable.

The following figure shows a "pig" mesh rendered with five light sources of different colors. Note the multiple specular highlights.

Getting ready

Set up your OpenGL program with the vertex position in attribute location zero, and the normal in location one.

How to do it...

To create a shader program that renders using the ADS (Phong) shading model with multiple light sources, use the following steps:

  1. Use the following vertex shader:

    layout (location = 0) in vec3 VertexPosition;
    layout (location = 1) in vec3 VertexNormal;
    
    out vec3 Color;
    
    struct LightInfo...