While playing with Isosurface functions in media, I found that I want the
"threshold" keyword inside my density but I have not found a way to do it.

I tried various ways of including it into a declared texture and placing it
in several places in the density itself. I suspect that I will have to build
it into the function where all values descend to zero and stay there, which
means no sine/cosign type things...8-(

The thing I am trying to do right now is toroidal media using "torus"<...>
which gives me a torus, but then also shows the points of a torus which
surrounds that torus.... not fun.

Any Ideas?

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The threshold keyword simply sets the value that is searched for when
finding the surface of the object, it has nothing to do with the
function itself. Not really sure what you are looking for...maybe the
min and max functions?
min(A, B) will return A or B, depending on which is lowest. max() works
the same, but returns the greater one. If you use 1 for one of the
values, and the density function for the other, it will return the value
of the density function if it is less than 1, otherwise it will return
1.

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Here's a formula that John VanSickle gave me when I was looking for a
way to make toroidal media:

sqrt( y*y + (sqrt(x*x+z*z)-1)*(sqrt(x*x+z*z)-1) )

This makes a torus of major and minor radii 1. Some tweaking of the
frequency and phase keywords might be necessary. Enjoy.


Peter Popov
ICQ: 15002700

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Why don't you try using a color map? Something like

     density{
       function{ ... }
       color_map{
         [0   rgb 0]
         [0.5 rgb 0]
         [1.0 rgb 1]
       }		
     }

	This should clamp the values of density to 0 (i.e. transparent) unless
function is > 0.5. Is that what you're going for?

	In Him,
	Ben

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Thanks, that's what I did. See p.b.i. "Accretion". The thin flaming ring is
the result so far. Could have been done with a disk 8-( My hope was to build
my other flames along turbulent toroidal magnetic lines... still in the
future somewhere.

Ben Birdsey <bbi### [at] unlgrad1unledu> wrote in message
news:37D34B2C.4FC3B474@unlgrad1.unl.edu...
> Why don't you try using a color map? Something like
>
>      density{
>        function{ ... }
>        color_map{
>          [0   rgb 0]
>          [0.5 rgb 0]
>          [1.0 rgb 1]
>        }
>      }
>
> This should clamp the values of density to 0 (i.e. transparent) unless
> function is > 0.5. Is that what you're going for?
>
> In Him,
> Ben

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Thanks!
        Hmmm.. This makes three ways to make a torus, I wonder how many
there are?

Peter Popov <pet### [at] usanet> wrote in message
news:YEHTN98AgfONAna9Zlxr9xZUrTnB@4ax.com...
> Here's a formula that John VanSickle gave me when I was looking for a
> way to make toroidal media:
>
> sqrt( y*y + (sqrt(x*x+z*z)-1)*(sqrt(x*x+z*z)-1) )
>
> This makes a torus of major and minor radii 1. Some tweaking of the
> frequency and phase keywords might be necessary. Enjoy.
>
>
> Peter Popov
> ICQ: 15002700

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Let's cook some donuts (ways to make a torus):

torus
quartic
poly (he he he)
mesh
bicubic_patches
unioned/merged spheres/blobs/cylinders/whatever
isosurface function
density_file surface pigment isosurface
two height_fields
lathe/sor
cylinder + bend.inc

Anyone for any more?


Peter Popov
ICQ: 15002700

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On Mon, 6 Sep 1999 20:20:30 -0400, "Bill DeWitt"
<the### [at] earthlinknet> wrote:

>Thanks, that's what I did. See p.b.i. "Accretion". The thin flaming ring is
>the result so far. Could have been done with a disk 8-( My hope was to build
>my other flames along turbulent toroidal magnetic lines... still in the
>future somewhere.

Todoidal magnetic lines? Did you just say that? I think I can help you
:) With the invaluable help of Axel Hecht I was able to create a macro
which calculates the magnetic field vector and intensity in any point
in space. The macro needs a PCM1 file as input but a torus mesh can be
easily created with SPatch or anything else you can think of.


Peter Popov
ICQ: 15002700

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sphere_sweep

Margus

Peter Popov wrote:
> 
> Let's cook some donuts (ways to make a torus):
> 
> torus
> quartic
> poly (he he he)
> mesh
> bicubic_patches
> unioned/merged spheres/blobs/cylinders/whatever
> isosurface function
> density_file surface pigment isosurface
> two height_fields
> lathe/sor
> cylinder + bend.inc
> 
> Anyone for any more?
> 
> Peter Popov
> ICQ: 15002700

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Peter Popov <pet### [at] usanet> wrote:
: Let's cook some donuts (ways to make a torus):

: lathe/sor

  You can't make a torus with a sor.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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