Book Image

OpenGL 4 Shading Language Cookbook - Third Edition

By : David Wolff
Book Image

OpenGL 4 Shading Language Cookbook - Third Edition

By: David Wolff

Overview of this book

OpenGL 4 Shading Language Cookbook, Third Edition provides easy-to-follow recipes that first walk you through the theory and background behind each technique, and then proceed to showcase and explain the GLSL and OpenGL code needed to implement them. The book begins by familiarizing you with beginner-level topics such as compiling and linking shader programs, saving and loading shader binaries (including SPIR-V), and using an OpenGL function loader library. We then proceed to cover basic lighting and shading effects. After that, you'll learn to use textures, produce shadows, and use geometry and tessellation shaders. Topics such as particle systems, screen-space ambient occlusion, deferred rendering, depth-based tessellation, and physically based rendering will help you tackle advanced topics. OpenGL 4 Shading Language Cookbook, Third Edition also covers advanced topics such as shadow techniques (including the two of the most common techniques: shadow maps and shadow volumes). You will learn how to use noise in shaders and how to use compute shaders. The book 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)
Title Page
Packt Upsell

Creating a paint-spatter effect

Using high-frequency noise, it is easy to create the effect of random spatters of paint on the surface of an object. The following image shows an example of this:

We use the noise texture to vary the color of the object, with a sharp transition between the base color and the paint color. We'll use either the base color or paint color as the diffuse reflectivity of the shading model. If the noise value is above a certain threshold, we'll use the paint color; otherwise, we'll use the base color of the object.



Getting ready

Start with a basic setup for rendering using the Phong shading model (or whatever model you prefer). Include texture coordinates and pass them along to the fragment shader.

There are a couple of uniform variables that define the parameters of the paint spatters:

  • PaintColor: The color of the paint spatters
  • Threshold: The minimum noise value where a spatter will appear

Create a noise texture with high-frequency noise.

Make your noise texture available...