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

Tessellating a 3D surface


As an example of tessellating a 3D surface, let's render (yet again) the teapotahedron. It turns out that the teapot's dataset is actually defined as a set of 4 x 4 patches of control points, suitable for cubic Bezier interpolation. Therefore, drawing the teapot really boils down to drawing a set of cubic Bezier surfaces.

Of course, this sounds like a perfect job for tessellation shaders! We'll render each patch of 16 vertices as a patch primitive, use quad tessellation to subdivide the parameter space, and implement the Bezier interpolation within the tessellation evaluation shader.

The following image shows an example of the desired output. The left teapot is rendered with inner and outer tessellation level 2, the middle uses level 4, and the teapot on the right uses tessellation level 16. The tessellation evaluation shader computes the Bezier surface interpolation:

First, let's take a look at how cubic Bezier surface-interpolation works. If our surface is defined...