This book presents a selection of modern rendering algorithms through the documented source code for a complete rendering system. All of the images in this book, including the ones on the front and back covers, were rendered by this software. The system, lrt, is written using a programming methodology called literate programming that mixes prose describing the system with the source code that implements it. We believe that the literate programming approach is a valuable way to introduce ideas in computer science and computer graphics. Often, some of the subtleties of an algorithm can be missed until it is implemented; seeing someone else’s implementation is a good way to acquire a solid understanding of an algorithm’s details. Indeed, we believe that deep understanding of a smaller number of algorithms provides a stronger base for further study of graphics than superficial understanding of many.