Hey, gang.

I'm still working on that dang bussard collector, and I'm thinking I
should try simulating plasma inside it by means of media.  So I opened
the handy-dandy documentation, and got confused right off (is anyone
surprised? (don't answer that)).

I'm creating a container object out of glass, which obliges me to use
the interior { I_Glass } statement (though, as a side note, it seems
that I_Glass isn't really anything but an ior 1.5?), and then I'd like
to put the media inside a hollow space (created with the 'hollow'
keyword, natch), but I don't understand... do I use a second interior {}
statement?  Do I do interior { I_Glass media [blah, blah, blah]}?

Thanks in advance.

-- 
Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
McK### [at] maccom   |					-- Justine Devlin, M.D.

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Dawn McKnight wrote:
> 
> I'm creating a container object out of glass, which obliges me to use
> the interior { I_Glass } statement (though, as a side note, it seems
> that I_Glass isn't really anything but an ior 1.5?)

Yes, I_Glass is just interior{ior 1.5} so if you create your own pigment &
finish for your glass, you could just as well forgo th I_Glass and use
interior{ior 1.5}

> Do I do interior { I_Glass media [blah, blah, blah]}?
> 

If you use the declared I_Glass interior, then the above will work, yes (of
course it's media{...} not media[...]).

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg

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Margus Ramst wrote:
> If you use the declared I_Glass interior, then the above will work, yes (of
> course it's media{...} not media[...]).

Thanks, Margus.

I came home and played with that, and I'm getting an odd behavior that's
making me want to tear my hair out, and I'm hoping someone will have
some insight that will show me the error of my logic.

Let's say I have a cylinder, which I want to fill with media.  I declare
the cylinder, everything's fine, I make it hollow, I apply the texture
(T_Glass3), I apply the media, great.

Except that the hollow keyword causes a very thin skin of glass on a
volume of media, which isn't actually what I want... I want a fairly
thick skin of glass.  So, I do a CSG difference, and scale the cylinder
smaller, use it to difference the larger version of itself, and try
applying media to the CSG object... and get nothing useful.

So I try setting the CSG object hollow, and I get an interesting, but
not useful effect... the area between the two cylinder walls fills with
media.  I look at the documentation for the hollow keyword, try
explicitly setting the larger cylinder not hollow, and the smaller one
hollow, fill with media... and get nothing useful.

How do I get the media to go into the 'hole' created by the smaller
cylinder when it's differenced from the larger one?


-- 
Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
McK### [at] maccom   |					-- Justine Devlin, M.D.

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"Dawn McKnight" <mck### [at] maccom> wrote in message
news:3A1### [at] maccom...
<snip>
> How do I get the media to go into the 'hole' created by the smaller
> cylinder when it's differenced from the larger one?

To answer this specific question, it sounds to me like you need to place an
additional cylinder inside the CSG to 'fill' the hole that u created, and
fill this cylinder with your media. Maybe scale it fractionally smaller, to
avoid POV getting confused over where the edge of the glass cylinder ends
and the media cylinder start ( not sure if this last step entirely necc.)
The outer CSG will just have your {T_Glass3} texture.

Oh yes, and welcome to the often frustrating but ultimately rewarding world
of 'media'.

All the best,

Andy Cocker
---------------------------------------------------------------
www.mariner9.net

..... for my music and graphics.
---------------------------------------------------------------
'I spilled spot remover on my dog. He's gone now. '
'I went to a restaurant that serves "breakfast at any time."
So I ordered french toast during the Renaissance. '

 - Steven Wright.

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Andy Cocker wrote:
> Maybe scale it fractionally smaller, to
> avoid POV getting confused over where the edge of the glass cylinder ends
> and the media cylinder start ( not sure if this last step entirely necc.)

I'll try it both ways; thanks.  It occurs to me to ask at this point how
many digits of precision POV-Ray computes when examining congruence of
surfaces?  Is 1.99 functionally any different from 1.9999999999999999?

> Oh yes, and welcome to the often frustrating but ultimately rewarding world
> of 'media'.

Gosh, thanks. 8|

-- 
Dawn McKnight      | "Who cares what the hipbone's connected to? I'm in Neurology!"
McK### [at] maccom   |					-- Justine Devlin, M.D.

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In article <3A1### [at] maccom>, mck### [at] maccom wrote:

> Except that the hollow keyword causes a very thin skin of glass on a
> volume of media,

Wrong. The "hollow" keyword only affects media, the cylinder is still a 
solid object, it just can be filled with media.
If you want to put media in a glass tube, use CSG difference to subtract 
a smaller cylinder from the larger one to make your glass tube, and put 
another small cylinder inside it, slightly larger or smaller than the 
other tube to avoid cooincident surfaces. Only this smaller cylinder 
needs to be hollow and filled with media.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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