1 2\subsection{Atmospheric effects} 3\RAY\ currently only implements one atmospheric effect, 4simple distance-based fog. 5 6\subsubsection{Fog} 7\index{fog} 8\RAY\ provides a simple distance-based fog effect intended to provide 9functionality similar to that found in OpenGL, for compatibility with 10software that requires an OpenGL-like fog implementation. Much like 11OpenGL, \RAY\ provides linear, exponential, and exponential-squared fog. 12 13\begin{verbatim} 14 FOG 15 LINEAR START 0.0 END 50.0 DENSITY 1.0 COLOR 1.0 1.0 1.0 16\end{verbatim} 17 18\begin{verbatim} 19 FOG 20 EXP START 0.0 END 50.0 DENSITY 1.0 COLOR 1.0 1.0 1.0 21\end{verbatim} 22 23\begin{verbatim} 24 FOG 25 EXP2 START 0.0 END 50.0 DENSITY 1.0 COLOR 1.0 1.0 1.0 26\end{verbatim} 27 28 29 30