In article <8EE68726Aseed7@204.213.191.228>, ing### [at] homenl (ingo) 
wrote:

> From the POV-doc on turbulence:
> "It says in effect "Don't give me the color at this spot... take a few 
> random steps in different directions and give me that color"."
> 
> I know very little of the way graphic software works. I was thinking, 
> instead of taking the random steps of turbulence, take "defined" steps as 
> in a convolution matrix.

It might be possible to do that, but you would have to specify the size 
of the sampling rectangle as well. You would also need to orient the 
sampling rectangle to be parallel to the surface, and have the same 
orientation as it's neighboring points. That is the difficult part, and 
I don't know how it would be done.(maybe just by using the angle to the 
xz plane and angle around the y axis?)

Or you could have the matrix always be aligned with the origin(with 
rotations and other transforms, of course). This would be a lot easier 
to implement, but it wouldn't follow the surface of the object. And to 
do it well would probably require a 3D array of values, like 3*3*3.

I will look into this, I think all it would require is multiple calls to 
Compute_Pigment with the evaluation point moved in the right way. And it 
would be restricted to pigment, since it operates on colors instead of 
patterns, like turbulence does. And it probably wouldn't be very fast.

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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