How can I make an ellipse (cylinderical)?

Thanks for your help.

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In article <4061d956$1@news.povray.org> , "John" <joh### [at] msncom> wrote:

> How can I make an ellipse (cylinderical)?

You scale a sphere asymetrically.  I.e. add "scale <1,10,1>" to a sphere.

    Thorsten

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

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

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"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:4061dc5d$1@news.povray.org...
> In article <4061d956$1@news.povray.org> , "John" <joh### [at] msncom>
wrote:
>
> > How can I make an ellipse (cylinderical)?
>
> You scale a sphere asymetrically.  I.e. add "scale <1,10,1>" to a sphere.
>
>     Thorsten
>

same goes with a cylinder.
cylinder {
    <0, 1, 0>,
    <0, -1, 0>, 1
    scale <3, 1, 1>
    //... and so on
}

or if you want a thin flat one, a disc object could be scaled.

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Thorsten Froehlich <tho### [at] trfde> wrote:
> > How can I make an ellipse (cylinderical)?

> You scale a sphere asymetrically.  I.e. add "scale <1,10,1>" to a sphere.

  Actually that's an ellipsoid.
  (Colloquially, that is. I wouldn't bet my money on whether a
mathematician would agree...)

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -

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Warp wrote:..
> Thorsten Froehlich <tho### [at] trfde> wrote:
> > > How can I make an ellipse (cylinderical)?
> 
> > You scale a sphere asymetrically.  I.e. add "scale <1,10,1>" to a sphere.
> 
>   Actually that's an ellipsoid.
>   (Colloquially, that is. I wouldn't bet my money on whether a
> mathematician would agree...)
> 
> 
Of course that's an ellipsoid. 
An ellipse is a curve. One can find many examples to represent a curve 
using povray. Best of all is starting with a parametrical representation 
for the curve. x = a*cos(t), z=b*sin(t), y=0 (0<=t<=2*pi) represents an 
ellipse in the (XZ)-plane with axes 2a and 2b.
One method to represent curves using povray consists in constructing 
small cylinders, an other method in constructing small spheres in 
neighbouring points.
-- 
home page: http://cage.ugent.be/~hs

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HermanS <sas### [at] pandorabeinvalid> wrote:
> Of course that's an ellipsoid. 
> An ellipse is a curve. One can find many examples to represent a curve 
> using povray. Best of all is starting with a parametrical representation 
> for the curve. x = a*cos(t), z=b*sin(t), y=0 (0<=t<=2*pi) represents an 
> ellipse in the (XZ)-plane with axes 2a and 2b.

  I know that an ellipse is a curve and its mathematical representation.
However, what I said is that I wouldn't bet my money on claiming that
an unevenly scaled sphere is a mathematically correct ellipsoid (at least
not without trying to get the mathematical relation between the two).

  It's an ellipsoid in the colloquial sense of "elongated sphere", but
is it an ellipsoid as defined mathematically is another question. :)

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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Can we use this "scale" with torus?



"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:4061dc5d$1@news.povray.org...
> In article <4061d956$1@news.povray.org> , "John" <joh### [at] msncom>
wrote:
>
> > How can I make an ellipse (cylinderical)?
>
> You scale a sphere asymetrically.  I.e. add "scale <1,10,1>" to a sphere.
>
>     Thorsten
>
> ____________________________________________________
> Thorsten Froehlich, Duisburg, Germany
> e-mail: tho### [at] trfde
>
> Visit POV-Ray on the web: http://mac.povray.org

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"John" <joh### [at] msncom> wrote in message news:40630650$1@news.povray.org...
> Can we use this "scale" with torus?

You can use any scale you like with a torus - just remember to charge them torus
rates...

Sorry. Yes. You can.

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In article <4062e844@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   It's an ellipsoid in the colloquial sense of "elongated sphere", but
> is it an ellipsoid as defined mathematically is another question. :)

A sphere is technically an ellipsoid. All shapes formed by uneven 
scaling of spheres are ellipsoids, and are described by the equation:

x^2/a^2 + y^2/b^2 + z^2/c^2 = 1

Anyway, a "cylinderical ellipse" doesn't make sense, but the 
"cylinderical" part is making me think of an elliptic cylinder:
http://mathworld.wolfram.com/EllipticCylinder.html

x^2/a^2 + y^2/b^2 = 1

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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