In article <3CC44E3B.C2AC4E53@gmx.de> , Tim Nikias <tim### [at] gmxde>  wrote:

> For one: If objects are misplaced, that may be the case.
> But what do you make of the ghost-appearances?
> Or parts of objects being cut off? That doesn't make much
> sense

The numbers vnormalize(0) would return on Windows were occasionally just out
of range and not NaNs (not a number).  Floating-point numbers as presented
internally in computers contain several "states", not just numbers.  One other
state is "Infinite".  if one of those ends up in a calculation is propages
through it and essentually caues the whole calculation to return an invalid
result.  If this for some reason happens only to one or two components of a
vector needed in tha clalculation it may still in other calculation of the
intersection result in valid vector components.  If this happens you get a
"partial" problem, i.e. a bit may occasionally appear correct.  However, the
point is that it is "occasionally correct", not always incorrect.

See it like a puzzle (I can't think of a better example):  If you flip all not
connected pieces so the image side is up you do see the whole image, but it is
of course not "the" whole image as you expect it.  What the vnormalize(0) does
here is move the pieces around and occasionally you see something close to
what you expect...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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Wasn't it ingo who wrote:
>in news:cW9### [at] econymdemoncouk Mike Williams wrote:
>
>> I would prefer to retain the "param.inc" versions of the examples on
>> my Isosurface tutorial page, because they are so much faster than
>> real parametrics. At the moment over half of them fail to run under
>> RC2. 
>> 
>
>Think you misunderstood me, the code was from an newer version of
>param.inc that accepts functions directly and looks even more like the
>parametric object. 

When is that going to become available?

-- 
Mike Williams
Gentleman of Leisure

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in news:fnK### [at] econymdemoncouk Mike Williams wrote:

> When is that going to become available?
> 

I'll try and set up a page for it and some other stuff this week, but 
promise nothing.

Ingo

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Ah, okay. Thats reasonable. Thanks for the explanation!

Thorsten Froehlich wrote:

> The numbers vnormalize(0) would return on Windows were occasionally just out
> of range and not NaNs (not a number).  Floating-point numbers as presented
> internally in computers contain several "states", not just numbers.  One other
> state is "Infinite".  if one of those ends up in a calculation is propages
> through it and essentually caues the whole calculation to return an invalid
> result.  If this for some reason happens only to one or two components of a
> vector needed in tha clalculation it may still in other calculation of the
> intersection result in valid vector components.  If this happens you get a
> "partial" problem, i.e. a bit may occasionally appear correct.  However, the
> point is that it is "occasionally correct", not always incorrect.
>
> See it like a puzzle (I can't think of a better example):  If you flip all not
> connected pieces so the image side is up you do see the whole image, but it is
> of course not "the" whole image as you expect it.  What the vnormalize(0) does
> here is move the pieces around and occasionally you see something close to
> what you expect...
>
>     Thorsten
>

--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Email: Tim### [at] gmxde

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