Soil Modeling

What do you mean by "slippage" and what sort of manipulation? What is program supposed to do?

are you looking at doing a completely realistic model or something that's more of a "close enough" model. My guess is that the former would take at least full seconds to compute each frame, the latter could reasonably plug into a game engine.

My limited understanding of soil mechanics is that it's very similar to fluid dynamics just with bigger particles. To do a realistic model you probably just need to do physics interactions with hundreds of millions of tiny particles (the large number is why you have the slowass rendering times). To do a "close enough" algorithm you could probably get away with something like metaballs (google it).

I dunno tho. This really isn't my expertise.

-me

Metaballs are pretty hard to find in comprehensible packages, but here's a good thread on the subject of Metaballs/Isosurface Extraction/Volume Rendering:

http://www.gamedev.net/community/forums/topic.asp?topic_id=171259

And here's a good example of Metaballs, it was pretty well written(enough for a n00b like me to port from DirectX to OpenGL =)

http://www.programmersheaven.com/2/Fast-metaballs