I have found a problem with the way sphere sweeps cast shadows, and I have
not seen anything about this but I may have missed it.  I started with a simple
sphere sweep with b_spline and tolerance 1 and I may have made some sort of
error here.  However, I played with this a little and decided to put a couple of
other objects in the scene for reference.
    Obviously, if there are sections of a sphere sweep that are "control"
segments, they will be invisible and you would not render them or their shadows-
no_shadow is the key here, I think.  But the first segment is control and should
be invisible with no_shadow in effect, and that I understand.  It appears that
the second segment is still flagged for no_shadow in the routine, and so while
it renders, it will leave a gap.  Probably something very simple to fix in the
source.
    Any POVers have this occur?  I can post an image in another group if you
have to see this, as well as source code.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

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Okay, I have played with this some more and found that setting the tolerance
value low gets rid of this.  I suppose that my unfamiliarity with the sphere
sweep made this goof possible.  Never mind.  I should have read the
documentation a little more carefully.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip


"Sir Charles W. Shults III" <aic### [at] cflrrcom> wrote in message
news:3cedc87e$1@news.povray.org...
>     I have found a problem with the way sphere sweeps cast shadows, and I have
> not seen anything about this but I may have missed it.  I started with a
simple
> sphere sweep with b_spline and tolerance 1 and I may have made some sort of
> error here.  However, I played with this a little and decided to put a couple
of
> other objects in the scene for reference.
>     Obviously, if there are sections of a sphere sweep that are "control"
> segments, they will be invisible and you would not render them or their
shadows-
> no_shadow is the key here, I think.  But the first segment is control and
should
> be invisible with no_shadow in effect, and that I understand.  It appears that
> the second segment is still flagged for no_shadow in the routine, and so while
> it renders, it will leave a gap.  Probably something very simple to fix in the
> source.
>     Any POVers have this occur?  I can post an image in another group if you
> have to see this, as well as source code.
>
> Cheers!
>
> Chip Shults
> My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
>
>
>
>

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I experienced a similar problem and posted a beta bug report about it, but
no one responded. How did you say you fixed it? I'm willing to bet it *is* a
bug; for me, it only occured when I set the spheresweep to no_image.

 - Slime
[ http://www.slimeland.com/ ]

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I set tolerance to a low value - like 0.01 or so.  But I think this really
is a bug, just not a very important one and it has a workaround.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

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Slime <slm### [at] slimelandcom> wrote:

> I experienced a similar problem and posted a beta bug report about it, but
> no one responded. How did you say you fixed it? I'm willing to bet it *is* a
> bug; for me, it only occured when I set the spheresweep to no_image.

If he really set the tolerance to 1, this value is much too big,
usually. The tolerance describes how far a (reflected) ray must *at
least* travel from the surface of the object towards a light to not cast
a shadow. This value should be very small, close to the pre-set
0.000001. Making it bigger should lead o less self-shading, but setting
it to 1 may cause other funky effects. :)

Jochen Lippert

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