Volumetric clouds. This is one of those topics I see coming up again and again. The first ever technique I ever saw was a 'realtime' cloud animation algorithm that ran at about ~1fps on my now ancient Pentium II 200MHz. At the time that was a lot of horsepower :-) Right now there is an IOTD up on the front page of some guys cloud effect. After following his link for an explanation of his technique he's being all hush hush about it. Why though? You take your own knowledge for free. Ah well, I guess we're all in the rat race.
Anyway. Mega particles. I first found this technique in ShaderX5 and followed up with a Google search. If you watch ">the video trailers for Windlight in Second Life then you may notice a pattern in the cloud animation that looks somewhat uniform .. Yes, it looks suspiciously like mega particles to me. When you see mega particles in action (like you can if you buy ShaderX5 because there's a demo with source on the CD) then you will notice that the effect is pretty much equivalent. Throw in some physics to better simulate the sunlight, some ray casts and ray-sphere collisions later and all of a sudden you could have a really nice atmospheric simulation solution which will even run on some pretty old hardware.
Wow. To think Second Life actually bought the whole company to get a hold of that tech.. The mind boggles :-)
ShaderX5:- Wolfgang Engel ISBN: 1-58450-499-4
