"Chris Capel" <chr### [at] hotmailcom> writes:

> I just downloaded the Iso-Surface patch and I want to use it with Pov to
> create a stone block to build a castle wall with.  The rounded_box function
> works fine as far as shape, but I need to figure out how to add a normal
> function to it.  I am totally new to Iso-Surface, so any help would be
> appreciated.

I assume that you actually want to modify the shape of the rounded_box
and not only the normal. Let me first talk about how isosurfaces work.

Given a function 
f: IR^3     -> IR 
   (x,y,z) |-> f(x,y,z)
the isosurface is the set of points where the function f evaluates to 
zero. So modifying the object results in modifying the function.
For some small changes of the surface, it is sufficent to add one
or more noisy functions to f. Of course, the values should be small
compared to the values of f.

So, you will have to add some modifying terms to the rounded_box function.
An example how this can be achieved is the grid at
http://www.public.usit.net/rsuzuki/e/povray/iso/exmpl1.html#rusty_mesh
It should be possible to apply this technique to rounded_box to get some
nice stones.

I hope this helps.

Thomas

-- 
http://www.fmi.uni-konstanz.de/~willhalm

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