The Ray Tracing in One Weekend series of books are now available to the public for free in PDF form, along with the accompanying source code. Releases are available directly from GitHub, or from Eric Haine's Real-Time Rendering site. Alternatively, you can purchase the Kindle version of this series from Amazon.com. Half of the proceeds of these sales go to Hack the Hood, a really neat organization.
In Ray Tracing In One Weekend and Ray Tracing: the Next Week, you built a “real” ray tracer.
In this volume, I assume you will be pursuing a career related to ray tracing and we will dive into the math of creating a very serious ray tracer. When you are done you should be ready to start messing with the many serious commercial ray tracers underlying the movie and product design industries. There are many many things I do not cover in this short volume; I dive into only one of many ways to write a Monte Carlo rendering program. I don’t do shadow rays (instead I make rays more likely to go toward lights), bidirectional methods, Metropolis methods, or photon mapping. What I do is speak in the language of the field that studies those methods. I think of this book as a deep exposure that can be your first of many, and it will equip you with some of the concepts, math, and terms you will need to study the others.
As before, www.in1weekend.com will have further readings and references.
If you spot errors or have suggested corrections, please submit issues via GitHub.
Thanks to Dave Hart and Jean Buckley for help on the original manuscript. Thanks to Paul Melis, Nakata Daisuke, Filipe Scur, Vahan Sosoyan, and Matthew Heimlich for finding errors.