In article <38BB0C0C.91144244@spiritone.com>, Josh English 
<eng### [at] spiritonecom> wrote:

> I suspect those are above my head, the problem is that grasspatch makes a
> whole bunch of individual splines. I can move all of them uniformly, but
> it probably won't look as good.

Actually, they are pretty simple:
    The first function, vtransform(), just applies a transform like 
scale, rotate, translate, matrix, or a sequence of these in a transform 
{} block to a point vector, moving it as they would an object.

    The vturbulence() function applies turbulence to a point vector. If 
you used this in the calculations for the grass positions, it would be 
the same as turbulating the grass.

    The eval_pattern() function takes a point vector and a pattern, and 
returns the value at that point(between 0 and 1 for most patterns, 
although there are exceptions).

    The eval_pigment() function does the same thing, except that it 
takes a pigment instead of a pattern and returns a rgb color vector. If 
you use position vectors in the color_map of the pigment and use the 
result of the function in your calculations for the grass, you could 
simulate things like waving grass.
Or you could use a combination of these, like vturbulence() with 
eval_pattern() controlling the amount of turbulence.

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

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