POV-Ray : Newsgroups : povray.beta-test : prism / lathe bug? Server Time
30 Jul 2024 04:11:03 EDT (-0400)
  prism / lathe bug? (Message 1 to 3 of 3)  
From: cadman
Subject: prism / lathe bug?
Date: 21 Jan 2002 10:49:41
Message: <3c4c3895$1@news.povray.org>
Should it still be permissable to define a spline in quadrants III and IV?

e.g.

lathe {
4
<-0.5, 3.5>, <-1, 4>, <-1.5, 3.5>, <-1, 3>
}

This should revolve a diamond shape around the y-axis, right?  It tells me
that the point is invalid.

PIII-700, 128MB
NT 4.0
Beta 10

Thanks!


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From: cadman
Subject: Re: prism / lathe bug?
Date: 21 Jan 2002 10:51:03
Message: <3c4c38e7@news.povray.org>
This is the actual code, I left out a line in my original post.

lathe {
linear_spline
4
<-0.5, 3.5>, <-1, 4>, <-1.5, 3.5>, <-1, 3>
}


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From: bob h
Subject: Re: prism / lathe bug?
Date: 23 Jan 2002 00:07:36
Message: <3c4e4518@news.povray.org>
"cadman" <cad### [at] graffitinet> wrote in message
news:3c4c3895$1@news.povray.org...
>
> lathe {
> linear_spline
> 4
> <-0.5, 3.5>, <-1, 4>, <-1.5, 3.5>, <-1, 3>
> }
>
> This should revolve a diamond shape around the y-axis, right?  It tells me
> that the point is invalid.

Although it's not specifically stated in the documentation (unless I
overlooked it) that only positive 2D vectors be allowed, negative numbers
are often used as well.  I couldn't say why your example fails but there's
probably some limitation happening.  You can use positive signs on your
numbers and get a render fine; can also use negatives on the first and last
points.  Anyway, there does seem to be a limitation or even possibly a bug
but I can't judge on that, only confirm your observation.
BTW, the positive version of that should be identical to the negative
anyhow.

bob h


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