My understanding and experience with turbulence show that when applied
to a pigment pattern or surface normal the pattern is affected by some
form of pseudo random perturbation of the pattern it is applied to. In
many cases this is enough but there are times it would be nice to be
able to precisely predict how the pattern will be affected by the
turbulence modifier.

 Even better would be a way to specify a user defined pattern to the
turbulence such as one of the predefined wave types that may be used
with patterns themselves. When a user specifies a specific wave type
with a pigment/normal pattern the wave type chosen affects the slope
of that pattern. The idea with adding a pattern to the turbulence would
be to actually perturb the pattern itself in predictable patterns
rather than just the existing psuedo random pattern that is implemented
now.

  For example if you were using a simple gradient pigment pattern and
applied a triangle wave to the turbulence of the pattern the resulting
pigment pattern would look like this:

 /\/\/\/\/\/\/\ 

rather than the normal unpredictable result like this:

---\_____----~~~\


Suggested format would be:

turbulence [float/vector] [Wave_Type]

  The questions that arise are if this would be possible, is it already
possible using an existing method, and if it would be a useful function
that people would use. I know that iso-pigments rise to this challenge
to a certain degree but unless you are some form of mathematical genius
it is not really a good alternative for the mathematicaly challenged.


Personally I think it would make for some very interesting results and
would add a lot more power to the existing turbulence function.

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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