Mike Williams <nos### [at] econymdemoncouk> wrote:

> Eliminating threshold doesn't have any effect on the geometry, it just
> makes the maths easier.

Actually, in the case of the two aforementioned 'methods', the final object does
look a bit different from one to the other--the 'wart' protrudes further using
the docs' method, or else the main sphere has been decreased in size. Not sure
which, or why. Not a big deal, of course.
>
> The surface exists at all points where f(x,y,z) = threshold. So
>    function {P(x*2,y*(1.05-y/6),z*2)}
>    threshold 1
> is exactly the same as
>    function {P(x*2,y*(1.05-y/6),z*2) -1}
>    threshold 0

OK, got that. Thanks. I never understood that 'til now, although it's probably
in your tutorials and I just glossed over that part.  (Heretofore, I've had a
tendency to just leave threshold at it's default value, without even thinking;
it's rather 'unexplored territory' that I need to learn more about.)

> It's not the sharpness of the surface, but the rate of change of
> function that causes the max_gradient requirement...

Oh! I do see the point you're making. A new discovery for me. Thanks for
explaining!

Ken

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