In article <39c7daff$1@news.povray.org>, "Marc-Hendrik Bremer" 
<Mar### [at] t-onlinede> wrote:

> I don't feel as good, asking for isosurface-functions in .newusers, 
> but this could be that trivial that I do not dare to ask in one of 
> the other groups.

In general, math questions should go to povray.advanced-users.


> I need a function which represents a cone (with one of the radii =0) 
> in an isosurface. I tried to "generate" one using the cylinder 
> function (x*x +z*z -r*r) and modifying the radius by y. That is 
> probably the right way, but I don't know how to do it right. 
> Everything I can get is a somewhat parabolic-shape. My math is 
> already to rusty.

Sounds like you were using a non-0 value for the threshold...these give 
double-ended cones for me:
function {sqrt(sqr(x) + sqr(z)) - abs(y)}
function {sqrt(sqr(x) + sqr(z) - sqr(y))}

But you must use a threshold of 0.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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