Has anyone done one of these, either by CSG or isosurface?  I've been 
playing with stretched rings, but they just don't look right.

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I'd also be interested in how to do a mobius strip.

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"dave vanhorn" <mic### [at] gmailcom> wrote in message 
news:457cb234@news.povray.org...
> Has anyone done one of these, either by CSG or isosurface?  I've been 
> playing with stretched rings, but they just don't look right.
>

Not as a CSG or an isosurface, but have you considered using the text 
object.
Depending upon what you want it for, an 8 on it's side may serve your 
purposes.

camera {location <0,0,-1>}
light_source { <1, 2, -20> color rgb 1}

text {
  ttf "times.ttf","8",0.2, 0
  pigment {color rgb 1}
  scale <0.5,1,1>
  rotate z*90
  translate 0.3*x
}

Regards,
Chris B.

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"Chris B" <c_b### [at] btconnectcomnospam> wrote:
> "dave vanhorn" <mic### [at] gmailcom> wrote in message
> news:457cb234@news.povray.org...
> > Has anyone done one of these, either by CSG or isosurface?  I've been
> > playing with stretched rings, but they just don't look right.
> >
>
> Not as a CSG or an isosurface, but have you considered using the text
> object.
> Depending upon what you want it for, an 8 on it's side may serve your
> purposes.
>
> camera {location <0,0,-1>}
> light_source { <1, 2, -20> color rgb 1}
>
> text {
>   ttf "times.ttf","8",0.2, 0
>   pigment {color rgb 1}
>   scale <0.5,1,1>
>   rotate z*90
>   translate 0.3*x
> }
>
> Regards,
> Chris B.

I found the infinity symbol in the following Windows Fonts, code U+221E. If
it is of any help.
ZTZhongsong
NSimSun
New Gulim
MingLiu


Stephen

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"Chris B"  wrote in message <457d22d0@news.povray.org>:
>   ttf "times.ttf","8",0.2, 0

Real mathematicians would use CMSY10.

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"dave vanhorn"  wrote in message <457cb234@news.povray.org>:
> Has anyone done one of these, either by CSG or isosurface?

An infinity symbol is not a 3D object, so the question is: how do intend to
make it 3D? Do you want it infinitely thin? Flat but thick? Round?

You can do something easy with a sphere sweep:

  sphere_sweep {
    b_spline 
    9,
    <-2, -2, 0>, 0.2, 
    < 0,  0, 0>, 0.2,
    < 2,  2, 0>, 0.2,
    < 2, -2, 0>, 0.2,
    < 0,  0, 0>, 0.2,
    <-2,  2, 0>, 0.2,
    <-2, -2, 0>, 0.2,
    < 0,  0, 0>, 0.2,
    < 2,  2, 0>, 0.2
  }

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"dave vanhorn"  wrote in message <457cbdfb@news.povray.org>:
> I'd also be interested in how to do a mobius strip. 

That can be done with a parametric object:

  parametric { 
    function { (1 + v * sin(u / 2)) * cos(u) }
    function { v * cos(u / 2) }
    function { (1 + v * sin(u / 2)) * sin(u) }
    <0, -0.2>, <2 * pi, 0.2>
    contained_by { box { <-1.5, -1.5, -1.5>, <1.5, 1.5, 1.5> } }
  } 

This one is infinitely thin. If you want some thickness, you have to design
a path for the v parameter.

BTW, is it not possible to use vectorial arithmetics for parametric objects?

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> This one is infinitely thin. If you want some thickness, you have to 
> design
> a path for the v parameter.

Thanks, I'll check that out.
All my pov experience previous has been with CSG, this is new to me.

> BTW, is it not possible to use vectorial arithmetics for parametric 
> objects?

No idea.

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> Not as a CSG or an isosurface, but have you considered using the text
> object.
> Depending upon what you want it for, an 8 on it's side may serve your 
> purposes.


Thanks,  I did think of this last night, but the text ends up as a very 
harsh object, I haven't found any way to round the corners, or otherwise 
soften the appearance.
Something like a sphere sweep would be ideal.

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I'll give that a try too, thanks.

That's pov for ya, there's usually at least three ways you didn't think of, 
to do something.  :)

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