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From: ingo
Subject: Strange spline problem
Date: 10 Oct 2001 10:55:34
Message: <Xns9136AC2E64F60seed7@povray.org>
When I render the scene below, without changing anything, just hit the 
run button, the first three times all is ok, the fourth time the shape 
has changed and from then on it keeps changing.
 I reported this during the pre-beta period and no one could reproduce 
it then. Now I ran into the problem again.

---%<------%<---
#version 3.5;
global_settings {assumed_gamma 1.0}
camera {location  <0,0,-4> look_at 0}
light_source {<500,500,-500> rgb 1}

#declare Spl=spline{
   linear_spline
   0/4,< 0   , 0  , 0>  
   1/4,< 0.25, 0.5, 0>  
   2/4,< 0.50, 0.1  , 0>
   3/4,< 0.75, 0.9, 0>  
   4/4,< 1   , 0  , 0>  
}

#declare I=0;
#while (I<100)
   sphere{Spl(I/100),0.1 pigment {rgb 1}}
   #declare I=I+1;
#end 
---%<------%<---

PII 233MHZ 192MB NT4 SP6 POV-Ray 3.5-beta.6

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


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From: Bob H 
Subject: Re: Strange spline problem
Date: 10 Oct 2001 15:45:53
Message: <3bc4a571@news.povray.org>
"ingo" <ing### [at] homenl> wrote in message
news:Xns### [at] povrayorg...
> When I render the scene below, without changing anything, just hit the
> run button, the first three times all is ok, the fourth time the shape
> has changed and from then on it keeps changing.
>  I reported this during the pre-beta period and no one could reproduce
> it then. Now I ran into the problem again.

Maybe you've been working too hard.  Get some rest and check it again  :-)
Seriously though, I can't image a pov-script metamorphosing, it hasn't
achieved AI status yet.  Sorry, but I did try to be serious.
It sure remains the same shape after a dozen rerenders here.

Bob H.

> ---%<------%<---
> #version 3.5;
> global_settings {assumed_gamma 1.0}
> camera {location  <0,0,-4> look_at 0}
> light_source {<500,500,-500> rgb 1}
>
> #declare Spl=spline{
>    linear_spline
>    0/4,< 0   , 0  , 0>
>    1/4,< 0.25, 0.5, 0>
>    2/4,< 0.50, 0.1  , 0>
>    3/4,< 0.75, 0.9, 0>
>    4/4,< 1   , 0  , 0>
> }
>
> #declare I=0;
> #while (I<100)
>    sphere{Spl(I/100),0.1 pigment {rgb 1}}
>    #declare I=I+1;
> #end
> ---%<------%<---
>
> PII 233MHZ 192MB NT4 SP6 POV-Ray 3.5-beta.6
>
> Ingo
>
> --
> Photography: http://members.home.nl/ingoogni/
> Pov-Ray    : http://members.home.nl/seed7/
>
>
> Ingo
>
> --
> Photography: http://members.home.nl/ingoogni/
> Pov-Ray    : http://members.home.nl/seed7/


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From: Trevor Quayle
Subject: Re: Strange spline problem
Date: 10 Oct 2001 15:50:11
Message: <3bc4a673$1@news.povray.org>
No, I saw it the first time I tried his code but can't reporduce it now.
For the first few renders, it seemed as though points were missing.

-tgq

"Bob H." <omn### [at] msncom> wrote in message
news:3bc4a571@news.povray.org...
> "ingo" <ing### [at] homenl> wrote in message
> news:Xns### [at] povrayorg...
> > When I render the scene below, without changing anything, just hit the
> > run button, the first three times all is ok, the fourth time the shape
> > has changed and from then on it keeps changing.
> >  I reported this during the pre-beta period and no one could reproduce
> > it then. Now I ran into the problem again.
>
> Maybe you've been working too hard.  Get some rest and check it again  :-)
> Seriously though, I can't image a pov-script metamorphosing, it hasn't
> achieved AI status yet.  Sorry, but I did try to be serious.
> It sure remains the same shape after a dozen rerenders here.
>
> Bob H.
>
> > ---%<------%<---
> > #version 3.5;
> > global_settings {assumed_gamma 1.0}
> > camera {location  <0,0,-4> look_at 0}
> > light_source {<500,500,-500> rgb 1}
> >
> > #declare Spl=spline{
> >    linear_spline
> >    0/4,< 0   , 0  , 0>
> >    1/4,< 0.25, 0.5, 0>
> >    2/4,< 0.50, 0.1  , 0>
> >    3/4,< 0.75, 0.9, 0>
> >    4/4,< 1   , 0  , 0>
> > }
> >
> > #declare I=0;
> > #while (I<100)
> >    sphere{Spl(I/100),0.1 pigment {rgb 1}}
> >    #declare I=I+1;
> > #end
> > ---%<------%<---
> >
> > PII 233MHZ 192MB NT4 SP6 POV-Ray 3.5-beta.6
> >
> > Ingo
> >
> > --
> > Photography: http://members.home.nl/ingoogni/
> > Pov-Ray    : http://members.home.nl/seed7/
> >
> >
> > Ingo
> >
> > --
> > Photography: http://members.home.nl/ingoogni/
> > Pov-Ray    : http://members.home.nl/seed7/
>
>


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From: Bob H 
Subject: Re: Strange spline problem
Date: 10 Oct 2001 16:11:56
Message: <3bc4ab8c@news.povray.org>
"Trevor Quayle" <Tin### [at] hotmailcom> wrote in message
news:3bc4a673$1@news.povray.org...
> No, I saw it the first time I tried his code but can't reporduce it now.
> For the first few renders, it seemed as though points were missing.

Wanted to be certain so I output to 5 file names and opened into PSP then
did a Arithmatic difference on them.  Came up unchanged between them.
Those iteration-caused delineations is kind of like an illusion when looking
from one to the other which is what I figured was happening.  Doesn't mean
another computer isn't doing odd things with it though.

Bob H.


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From: Trevor Quayle
Subject: Re: Strange spline problem
Date: 10 Oct 2001 16:23:58
Message: <3bc4ae5e@news.povray.org>
If you look at the output shape of the code given, it looks like an M.  The
first few times I rendered it, whole lines of the M were missing to the
point that only one line was present one time it happened.

But as I say, I have been yet to reproduce it.  (Maybe I'm just not using
the right kind of weed now ;) )

But seriously, I did see it. In retrospect I wish I had thought of saving
the images as it happened.

-tgq


"Bob H." <omn### [at] msncom> wrote in message
news:3bc4ab8c@news.povray.org...
> "Trevor Quayle" <Tin### [at] hotmailcom> wrote in message
> news:3bc4a673$1@news.povray.org...
> > No, I saw it the first time I tried his code but can't reporduce it now.
> > For the first few renders, it seemed as though points were missing.
>
> Wanted to be certain so I output to 5 file names and opened into PSP then
> did a Arithmatic difference on them.  Came up unchanged between them.
> Those iteration-caused delineations is kind of like an illusion when
looking
> from one to the other which is what I figured was happening.  Doesn't mean
> another computer isn't doing odd things with it though.
>
> Bob H.
>
>
>


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From: Trevor Quayle
Subject: Re: Strange spline problem
Date: 10 Oct 2001 16:45:57
Message: <3bc4b385$1@news.povray.org>
Ah ha! I caught it.  I'm not sure how to reproduce it. I just ran the scene
over and over again.  See the two images in p.b-t.b


-tgq


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From: Bob H 
Subject: Re: Strange spline problem
Date: 10 Oct 2001 17:00:42
Message: <3bc4b6fa$1@news.povray.org>
Seeing is believing... what, I don't know exactly.

It would be plausible to me if this were only the five points (i<=5) and
somehow the last point being dropped out.  But this means the whole segment
becomes void, how can that be?  Not like the iterations are stopping at 80
or whatever and not continuing on with the while loop, so it must be a
spline problem.  Right?  Well, thinking about it, if the last point didn't
get placed I guess it could make the whole segment disappear.  That does
make some sense to me anyway.  Too bad I'm not a spline guru or I'd know for
sure I suppose.

Bob H.

"Trevor Quayle" <Tin### [at] hotmailcom> wrote in message
news:3bc4b385$1@news.povray.org...
> Ah ha! I caught it.  I'm not sure how to reproduce it. I just ran the
scene
> over and over again.  See the two images in p.b-t.b
>
>
> -tgq
>
>
>


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From: ingo
Subject: Re: Strange spline problem
Date: 10 Oct 2001 17:01:41
Message: <Xns9136EA40B58BFseed7@povray.org>
in news:3bc4b385$1@news.povray.org Trevor Quayle wrote:

> Ah ha! I caught it.

Thanks for confirming, thought I was going nuts.
Do you also get strange results when you change the type to quadratic 
or cubic splines in the same scene?

Ingo

-- 
Photography: http://members.home.nl/ingoogni/
Pov-Ray    : http://members.home.nl/seed7/


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From: Christian Volmer
Subject: Re: Strange spline problem
Date: 10 Oct 2001 17:04:51
Message: <3bc4b7f3$1@news.povray.org>
> Do you also get strange results when you change the type to quadratic
> or cubic splines in the same scene?

Yes, I do. Segments are missing again.

cu

Christian


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From: Gilles Tran
Subject: Re: Strange spline problem
Date: 22 Dec 2001 15:32:27
Message: <3c24eddb$1@news.povray.org>

Xns### [at] povrayorg...
> When I render the scene below, without changing anything, just hit the
> run button, the first three times all is ok, the fourth time the shape
> has changed and from then on it keeps changing.
>  I reported this during the pre-beta period and no one could reproduce
> it then. Now I ran into the problem again.

For the record, I just lost an hour trying to figure out a similar
problem...
I suspect that a variable is not reset properly between renders.

In the complete scene where the spline below is placed, subsequent renders
sometimes return an error saying that the base and apex points of the
cylinder are identical (and stop the parsing). It's not repeatable : the
problem appear at random with identical renders of the image.
I've been able to trap the problem by testing the base and apex point (so
that at least the parsing doesn't stop).
When the problem occurs, all the values for the spline value are <2,2,2>.
The scene where the problem appears is very large and because the bug is
random I've not been able to simplify it in a way that make it appear each
time (it doesn't appear with the code below).


3.5 beta 9, winnt 4 sp6


#declare rFil=0.007;
#declare xFil=2.5;
#declare spFil =
  spline {
    cubic_spline
    -0.15,<0,-0.35,0>,
    0,<0,-0.3,0>,
    0.1,<xFil*0.2,-0.2,0>,
    0.2,<xFil*0.3,-0.1,0>,
    0.3,<xFil*0.45,-0.0,0>,
    0.4,<xFil*0.55,0,0>,
    0.5,<xFil*0.6,-0.03,0>,
    0.6,<xFil*0.7,0,0>,
    0.7,<xFil*0.8,-0.08,0>,
    0.8,<xFil*0.9,0,0>,
    0.9,<xFil,0,0>,
    1.1,<xFil*1.1,-0.1,0>,
  }

union{
    #declare i=0;
    #while (i<1)
        cylinder {spFil(i), spFil(i+0.01),rFil}
        #declare i=i+0.01;
    #end
    pigment{rgb 1}
}

camera{
    location  <1.25, 0.2, -1.5>
    direction z*1.2
    right     image_width*x/image_height
    look_at   <1.25,0.2,  0>
}

background{rgb y+z}
light_source{<15,2,-4> color rgb 1}


--

**********************
http://www.oyonale.com
**********************
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- POV-Ray and Poser computer images
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