"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Kenneth" <kdw### [at] gmailcom> wrote:
>
> > Is the technique you refer to here
> > the same as Mike's 'thickening' trick using 2 parallel surfaces (page 18 of
> > 149)? Or is it something different?
>
> It is the same - yet with a slight difference.
>
> If you're trying to make a black pattern on a white background, you're going to
> want a solid black pattern, not a small gradient from -C to 0 to +C.
>
> So you just use select to make a discontinuous function.
>
> #declare Pattern = function {select (abs(F(x,y,z)-C, 0, 0, 1)}
>
> And then when you do plane {z, 0, pigment {function {Pattern (x, y, z)}}}, you
> get what you're probably expecting.
>
Great, thanks. Yes, you were reading my mind, ha. (Actually, my own use would be
the reverse-- a white pattern on a black background.) I'll test it and play...

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