1\section{Introduction} 2\RAY\ is designed to be a very fast renderer, based on ray tracing, 3and employing parallel processing to achieve high performance. 4 5At the present time, \RAY\ and its scene description language are fairly 6primitive, this will be remedied as time passes. For now I'm going to 7skip the ``intro to ray tracing'' and related things that should probably 8go here, they are better addressed by the numerous books on the subject 9written by others. This document is designed to serve the needs of 10sophisticated users that are already experienced with ray tracing 11and basic graphics concepts, rather than catering to beginners. 12If you have suggestions for improving this manual, I'll be glad 13to address them as time permits. 14 15Until this document is finished and all-inclusive, the best way to 16learn how \RAY\ works is to examine some of the sample scenes that 17I've included in the \RAY\ distribution. Although they are all very 18simple, each of the scenes tries to show something slightly 19different \RAY\ can do. Since \RAY\ is rapidly changing to accommodate 20new rendering primitives and speed optimizations, the scene 21description language is likely to change to some degree as well. 22 23\subsection{\RAY\ Feature List} 24 Although \RAY\ is a relatively simple renderer, it does have enough 25features that they bear some discussion. 26 27\begin{itemize} 28\item Parallel execution using MPI. 29\item Parallel execution using POSIX or Unix-International 30 threads libraries. 31\item Automatic grid-based spatial decomposition scheme for greatly 32 increased rendering speeds. 33\item Simple antialiasing based on psuedo-random supersampling. 34\item Linear, exponential, and exponential-squared fog. 35\item Perspective, orthographic, and depth-of-field camera projection 36 modes, with eye-space frustum controls. 37\item Positional, directional, and spot lights, with optional attenuation. 38\item Provides many useful geometric objects including 39 Spheres, Planes, Triangles, Cylinders, Quadrics, and Rings 40\item Texture mapping, with automatic MIP-map generation 41\item Supports rendering of volumetric data sets 42\end{itemize} 43 44 45