https://www.pbr-book.org/
Physically Based Rendering:From Theory To Implementation by Matt Pharr, Wenzel Jakob, and Greg Humphreys
The pbrt website has general information about both the Physically Based Rendering book as well as many other resources for pbrt. As of October 2018, the full text of the book 
is now available online, for free.
# Building pbrt – page
# Example scenes Over 8GB of example scenes are available for download. (Many are new and weren't available with previous versions of pbrt.) See the [pbrt-v3 scenes page](http://pbrt.org/scenes-v3.html) on the pbrt website for information about how to download them.
# Further Reading
Donald Knuth’s article Literate Programming (Knuth 1984) describes the main ideas behind literate programming as well as his web programming environment. The seminal TEX typesetting system was written with web and has been published as a series of books (Knuth 1986; Knuth 1993a). More recently, Knuth has published a collection of graph algorithms in literate format in The Stanford GraphBase (Knuth 1993b). These programs are enjoyable to read and are excellent presentations of their respective algorithms. The Web site www.literateprogramming.com has pointers to many articles about literate programming, literate programs to download, and a variety of literate programming systems; many refinements have been made since Knuth’s original development of the idea.
The only other literate programs we know of that have been published as books are the implementation of the lcc compiler, which was written by Christopher Fraser and David Hanson and published as A Retargetable C Compiler: Design and Implementation (Fraser and Hanson 1995), and Martin Ruckert’s book on the mp3 audio format, Understanding MP3 (Ruckert 2005).