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

Simulating smoke with particles


Smoke is characterized by many small particles that float away from the source, and spread out as they move through the air. We can simulate the floatation effect with particles by using a small upwards acceleration (or constant velocity), but simulating the diffusion of each small smoke particle would be too expensive. Instead, we can simulate the diffusion of many small particles by making our simulated particles change their size (grow) over time.

The following image shows an example of the results:

The texture for each particle is a very light "smudge" of grey or black color.

To make the particles grow over time, we'll make use of the GL_PROGRAM_POINT_SIZE functionality in OpenGL, which allows us to modify the point size within the vertex shader.

Note

Alternatively, we could draw quads, or use the geometry shader to generate the quads using the technique demonstrated in Chapter 6, Using Geometry and Tessellation Shaders.

Getting ready

Start with the basic particle...