i cruised through the net searching for a linux-tool that creates 
lathe-objects. i did not find one. so i tried to create a 
vinebottle step-by-step at my own. for smooth curves i use 
quadratic_splines and that seems to be my mysere. kept in mind that one 
curve depends on three neighbouring points everything went okay since i 
came to point six of lathe list where the neck of the bottle begins.
the result should be a Cabernet Sauvignon but it looks like a bottle that 
is fallen on its head.
may anyone tell me what i did not understand from the manual?
an image of it i sent to p.b.images.

gratitude

code follows:
--------------------------------------------start
#declare bottle=
lathe{
        quadratic_spline
        17,
        <-0.01,0>
        <0,0> ,         
        <0.065/2,0> ,
        <0.067/2,0.0025> ,
        <0.075/2,0.005>, 
        <0.075/2,0.175> ,
        <0.073/2,0.18> ,
        <0.07/2,0.185> ,
        <0.067/2,0.19> ,
        <0.06/2,0.195> ,
        <0.055/2, 0.20> ,
        <0.036/2,0.205> ,
        <0.028/2, 0.21> ,
        <0.028/2,0.285> ,
        <0.04/2,0.288> ,
        <0.04/2,0.292> ,
        <0.02,0.29>
        texture{T_Winebottle_Glass}
        finish{
                phong 0.6
                diffuse 0.3
                ambient 0.2
        }
}

object { bottle }
--------------------------------------------end

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"marabou" <not### [at] availableyet> wrote in message
news:3bdf3b18@news.povray.org...
>
> i cruised through the net searching for a linux-tool that creates
> lathe-objects. i did not find one. so i tried to create a
> vinebottle step-by-step at my own. for smooth curves i use
> quadratic_splines and that seems to be my mysere. kept in mind that one
> curve depends on three neighbouring points everything went okay since i
> came to point six of lathe list where the neck of the bottle begins.
> the result should be a Cabernet Sauvignon but it looks like a bottle that
> is fallen on its head.
> may anyone tell me what i did not understand from the manual?
> an image of it i sent to p.b.images.

It can be concave and convex at adjacent segments so maybe that's what went
wrong.  I don't think quadratic will seamlessly curve from segment to
segment, at least not without many extra points.
Suggest cubic_spline instead, although you need to use control points for
each actual surface point.  Like outlining the shape and then shifting
controls to get the intermediate surface shape.
I don't know of any Linux utilites for lathe but for Windows there is
Spiline which can be found in the povray.org links.

Bob H.

> code follows:
> --------------------------------------------start
> #declare bottle=
> lathe{
>         quadratic_spline
>         17,
>         <-0.01,0>
>         <0,0> ,
>         <0.065/2,0> ,
>         <0.067/2,0.0025> ,
>         <0.075/2,0.005>,
>         <0.075/2,0.175> ,
>         <0.073/2,0.18> ,
>         <0.07/2,0.185> ,
>         <0.067/2,0.19> ,
>         <0.06/2,0.195> ,
>         <0.055/2, 0.20> ,
>         <0.036/2,0.205> ,
>         <0.028/2, 0.21> ,
>         <0.028/2,0.285> ,
>         <0.04/2,0.288> ,
>         <0.04/2,0.292> ,
>         <0.02,0.29>
>         texture{T_Winebottle_Glass}
>         finish{
>                 phong 0.6
>                 diffuse 0.3
>                 ambient 0.2
>         }
> }
>
> object { bottle }
> --------------------------------------------end
>
>

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