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
Contributors
Preface
Index

Creating a rusted metal effect


This recipe combines a noise texture with the reflection effect covered in Chapter 5, Using Textures to create a simple rusted metal effect.

This technique is very similar to the previous recipe, Creating a paint-spatter effect.  We'll use our noise texture to modulate the reflection from the teapot. If the noise is above a certain threshold, we'll use the rust color, otherwise, we'll use the reflected color.

Getting ready

We'll combine the technique described in the Simulating reflection with cube maps recipe in Chapter 5, Using Textures, with a noise texture. Start with the shaders from that recipe.

How to do it...

In the fragment shader, we'll access our noise texture and if the value is below the threshold value Threshold, we'll use the reflected color (from the cube map), otherwise, we'll use a rust color:

in vec3 ReflectDir;
in vec2 TexCoord;

uniform samplerCube CubeMapTex;
uniform sampler2D NoiseTex;

uniform float ReflectFactor;
uniform vec4 MaterialColor...