Working on an in-buit f_turb and think I finally tracked down an issue 
which has harassed me for years.

Our turbulence moves with omega. This looks not right to me given what I 
understand Brownian Motion to be. The code is effectively unchanged 
since it was added in v3.0. I'd expect with increasing omega for the 
distribution to get larger and possibly larger than 1.0 (docs mention 
this). What seems amiss to me is the more or less linear shift in the 
center of the distribution with omega.

If you don't know turbulence is doing this, using it can be very 
confusing. "My isosurface foliage doesn't line up with my iso tree 
branches - and everything leans one way!"

The irid (comment there about Turbulence returning 0-1 range) and fog 
features use Turbulence() I see. Expect the vector version of turbulence 
affected too. Agate of course, though probably hard to see any shift 
there - or maybe with any traditional pattern. More shift goes with more 
noise typically.

In the attached image created a set up which shows the distribution 
moving from a center of 0.25 and range of 0.5 to a center of about 2.0 
and a range of 4 as you approach an omega of one. Other settings seem 
not to matter much to the distribution, except as looks OK to my eye.

I think the distribution should be centered at 0.1 coming out of 
Turbulence() and DTurbulence() and it being a smaller or larger 
Gaussian, but...

Making a new f_turb centered and using only that sort of turbulence with 
isosurfaces doesn't really fly. I want to exploit the pattern warp stuff 
extensively including turbulence.

Anyone know the history with turbulence? Thoughts, opinions?

I've not yet tried to understand why the distribution's center is 
moving. I also suspect it's not spreading as much as it should, but I 
care about that less.

Bill P.

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