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

Using functions in shaders

The GLSL supports functions that are syntactically similar to C functions. However, the calling conventions are somewhat different. In the following example, we'll revisit the ADS shader using functions to help provide abstractions for the major steps.

Getting ready

As with previous recipes, provide the vertex position at attribute location 0 and the vertex normal at attribute location 1. Uniform variables for all of the ADS coefficients should be set from the OpenGL side, as well as the light position and the standard matrices.

How to do it...

To implement ADS shading using functions, use the following code:

  1. Use the following vertex shader:

    layout (location = 0) in vec3 VertexPosition;
    layout (location = 1) in vec3 VertexNormal;
    out vec3 LightIntensity;
    struct LightInfo {
        vec4 Position; // Light position in eye coords.
        vec3 La;       // Ambient light intensity
        vec3 Ld;       // Diffuse light intensity
        vec3 Ls;       // Specular light intensity