This is a small project I created for the real time visualisation lab course at the Vienna University of Technology. It is based on my ever growing KOCMOC codebase.
It is basically a brute force (without optimisations) implementation of the 2002 GDC Presentation by Naty Hoffman and Arcot J. Preetham. It uses Mie and Rayleigh scattering and a few simplifications to achieve nicely looking results at only a few milliseconds even unoptimised.
Even though my results looks nice, I could not reproduce some effects from the paper/sample implementation. What is missing is the distinct red-yellowish tint of the sky when the sun is low on the horizon. I wrote a short documentation paper with more details and a comparison of the before mentioned case. It comes along with the Windows binary distribution package which you can find here (http://dl.dropbox.com/u/2370284/atmospheric_scattering.zip, ~30mb).
As always, the source files are licensed under the MIT license and assets are license under the creative commons license. See the repo and documentation for licensing details. The source code lives in the RTVIS branch inside the original KOCMOC repo on github (https://github.com/SimonWallner/kocmoc-demo/tree/RTVIS).