Warp, 
  I'm glad you threw in your 2cents.. I appreciate you taking time to comment.

  Here's the problem I have.. I, after the converstaion today, am fully lucid on the
noise3d function. (Of course I'm using MegaPov, so who knows).  I understand how it
randomly
puts or removes a surface to make it look like noise.  And I understand the function
part
of isosurfaces.  The problem I'm having now is, when I bound my isosurface to a box {}
it only does the noise on one side of teh box.. is there a way to make it round the y
axis?
And Not really round I guess, I'm doing:
  function { x - noise3d(x,y,z) }
And I just want to do the same thing but ont he opposite side.. 

Now would I have to do something like:
  function { x, sqrt(y^2+z^2), z - noise3d(x,y,z) }

Now, I'm still learning, so be gental.

Dave

Warp <war### [at] tagpovrayorg> wrote:
>   You can think about f_noise3d() (let's start speaking pov3.5, shall we?-) )
> as a "random" number generator which returns values between 0 and 1, inclusive.
>   Of course it's not a random number generator, but you can think about it
> as if it was.

>   This can be used, for example, to "randomly" vary the surface of your
> function. For example suppose that you have a sphere of radius 10 defined
> like this:

> #declare MySphere = function { x^2+y^2+z^2-10^2 }

>   Now if you want to displace the surface of the sphere randomly you can
> add noise to the radius:

> #declare MySphere = function { x^2+y^2+z^2-(10+f_noise3d(x,y,z))^2 }

>   This will cause the radius to vary between 10 and 11 in different parts
> of the sphere.

>   Of course the term "noise" is a bit misleading because it gives you smooth
> transitions, not random noise, but you got the idea, didn't you?

>   You can adjust the frequency of this "noise" about any axis by modifying
> the three parameters given to it. For example if you want noise that is
> twice as dense in all directions, you can do it like:

> #declare MySphere = function { x^2+y^2+z^2-(10+f_noise3d(x*2,y*2,z*2))^2 }

>   If you want less or more noise, you can multiply the return value of the
> noise function. For example if you want half of the displacement, you can
> do:

> #declare MySphere = function { x^2+y^2+z^2-(10+0.5*f_noise3d(x*2,y*2,z*2))^2 }


> -- 
> #macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
> rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
> ],13),8)-3,10>#end blob{N(array[6]{11117333955,
> 7382340,3358,3900569407,970,4254934330},0)}//                     - Warp -

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