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Greg M. Johnson <gre### [at] my-dejanews com> wrote in message
news:3879E51F.77B9A241@my-dejanews.com...
> How "should" an isosurface respond when there is an undefined region of
> space?
>
> I just ran something like
> function{noise3d(x^0.5/constant , y/constant , z/constant}
> . The result is symmetric about the x-axis!
>
> Is this an algorithm mistake?
*I* wouldn't want to get an error every time I had an isosurface
do (-1)^.5, but I think this is a very debatable topic.
What would you like the program to do in this case?
The isosurface stuff converts x to absolute value of x
before trying to use the ^. This is just to avoid many floating
point errors. The isosurface code does the same conversion
before applying sqrt() or ln().
Personally I think its OK, (but perhaps the program should put out
a warning). If you look at isosurface scenes posted in these newsgroups,
you will find a lot of square roots and logs of negative numbers being done,
and a lot of this is probably being done completely oblivious to the
mathematical inconsistency.
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