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Ron Parker <par### [at] fwi com> wrote :
>
> Even there, it's of limited usefulness if it has a fixed major radius.
>
Maybe I don't know what you mean. I was just thinking that I would be
happy with a major radius of 1 and a minor radius of 1. Everything else can
be done with density and scale. As long as the density starts at 1 along the
focus of the minor radius and goes to 0 and stays there.
Isosurface torus pretty much requires a toroidal container which means
that you cannot combine it with another media in the same container.
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On Thu, 16 Sep 1999 09:59:38 -0400, Buckaroo Bill wrote:
>
>Ron Parker <par### [at] fwicom> wrote :
>>
>> Even there, it's of limited usefulness if it has a fixed major radius.
>>
>
> Maybe I don't know what you mean. I was just thinking that I would be
>happy with a major radius of 1 and a minor radius of 1. Everything else can
>be done with density and scale. As long as the density starts at 1 along the
>focus of the minor radius and goes to 0 and stays there.
The problem is that if I want a toroidal density pattern with a major radius
of 1 and a minor radius of .1, I have to scale the pattern by 100 and then
put my entire color map into the range [0 .. 0.001] That doesn't scale very
well.
> Isosurface torus pretty much requires a toroidal container which means
>that you cannot combine it with another media in the same container.
Really? Are you sure?
//------------ cut here --------->8=========
#declare myfun=function{max(0,1-sqrt( y*y + sqr(sqrt(x*x+z*z)-5)))}
sphere { 0,6.1 hollow
interior { media {
density {function {myfun}}
emission .2 intervals 10 samples 5 5
}}
texture {pigment {color rgbt 1}}
}
light_source {<-20,20,-20> rgb 1}
camera {location <0,5,-10> look_at 0}
//------------ cut here --------->8=========
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Ron Parker <par### [at] fwicom> wrote
>
> Really? Are you sure?
>
Well, no, I wasn't sure (I should include a standard disclaimer whenever
I say any thing about POV and especially Isosurface). I had read someone's
recommendation (maybe your's?) to use max() but hadn't had a chance to try
it yet. Too many things on too few burners. Thanks.
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Larry Fontaine wrote:
>
> Suggestion for the next version of POV:
> A torus pattern, like the sphere one, but a torus...
> Would be major radius 1, along the X-Y or X-Z plane, with the value
> gradually dropping off from 1 at minor-radius 0 to 0 at minor-radius
> 1.
I posted source for two versions of this pattern, either to one of the
programming groups or to the unofficial patch group, with recommended
names of ring and donut (or something like that). One version returned
a value of 1 at the minor radius focal point, dropping to 0 when the
minor radius reached, and remaining at 0 for all points outside of the
torus. This was intended for smoke rings, angel's halos, parts of
neon sign lettering, etc.
The other version started with a value of 0 at minor_radius=0, rose
to 1 at minor_radius=1, and then repeated this range for minor radii>1.
This pattern was more suited for simulating the interior of curved
branches, etc.
The major radius was 1 for both patterns.
Regards,
John
--
ICQ: 46085459
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Alexander Enzmann wrote:
>
> It's not too hard to determine distance from a circle, but you do
> realize that a repeating torus pattern would look a little funny near
> the axis of symmetry...
Maybe the user wants the funny look...
--
ICQ: 46085459
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Hello? Earth to Ron...
You can scale it to any radius you want, and the minor radius is set by
adjusting the color_map numbers. Therefore ant torical shape you want.
Ron Parker wrote:
> On Thu, 16 Sep 1999 05:57:26 -0500, Chris Huff wrote:
> >The only place I think a torus pattern could be useful is in media. But
> >it would be extremely useful there. (flourescent bulbs, dust rings from
> >a shock wave, etc...)
>
> Even there, it's of limited usefulness if it has a fixed major radius.
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Larry Fontaine wrote:
>
> Suggestion for the next version of POV:
> A torus pattern, like the sphere one, but a torus...
> Would be major radius 1, along the X-Y or X-Z plane, with the value
> gradually dropping off from 1 at minor-radius 0 to 0 at minor-radius 1.
I have posted a patch for both the official source and the super-patch
which does exactly this.
And yes it does excelent smoke rings.
Cheers, PoD.
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On Thu, 16 Sep 1999 15:48:46 -0500, Larry Fontaine wrote:
>Hello? Earth to Ron...
>You can scale it to any radius you want, and the minor radius is set by
>adjusting the color_map numbers. Therefore ant torical shape you want.
Earth to David...
I said that. I also said that if you scale it to a major radius of 100
and a minor radius of .1, you have to keep your color map in the range
0 to .001. That's a small range, and we all know how well POV likes
small numbers, no?
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Larry Fontaine <lfo### [at] isdnet> wrote in message
news:37E00892.1BEC2B42@isd.net...
> Suggestion for the next version of POV:
> A torus pattern, like the sphere one, but a torus...
> Would be major radius 1, along the X-Y or X-Z plane, with the value
> gradually dropping off from 1 at minor-radius 0 to 0 at minor-radius 1.
>
Having played around some more, I wonder if there is a way to make a
torus pattern rotate along it's minor axis, so as to make a true smoke ring
animate?
I suspect that at this point it will take isosurface if it can be done
at all. It would have to be a radial pattern rotated around the major axis
somehow.
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On Fri, 17 Sep 1999 10:51:21 -0400, Buckaroo Bill wrote:
>Larry Fontaine <lfo### [at] isdnet> wrote in message
>news:37E00892.1BEC2B42@isd.net...
>> Suggestion for the next version of POV:
>> A torus pattern, like the sphere one, but a torus...
>> Would be major radius 1, along the X-Y or X-Z plane, with the value
>> gradually dropping off from 1 at minor-radius 0 to 0 at minor-radius 1.
>>
>
> Having played around some more, I wonder if there is a way to make a
>torus pattern rotate along it's minor axis, so as to make a true smoke ring
>animate?
>
> I suspect that at this point it will take isosurface if it can be done
>at all. It would have to be a radial pattern rotated around the major axis
>somehow.
Well, radial is just atan2(x,z) scaled and rotated appropriately. There isn't
yet an atan2 in the superpatch, but there will be. At that point, you'll be
able to compute a function like what you're looking for, but it won't be
pretty.
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