POV-Ray : Newsgroups : povray.general : rainbow-refraction Server Time
13 Aug 2024 09:27:39 EDT (-0400)
  rainbow-refraction (Message 1 to 8 of 8)  
From: Hendrik Knaepen
Subject: rainbow-refraction
Date: 14 Oct 1998 16:10:32
Message: <3624F6EC.F7CFF06F@skynet.be>
Hi,

With POV-Ray3.02 I could make a color-dependant-refractive-surface using
a texturemap with different filtered colors and different ior's.  Now
that the ior has been moved to the interior, this is no longer
possible.  At least not this way.  Is there another way to do this? And
I mean directly from POV-Ray, so rendering the image a few times with
changing refractions and colors is not what I want (it's too slow to do
on my 486DX2 66 (Yeah, you may laugh, it has only 12Mb Ram! :-) )

ZK

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From: =Bob
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 05:31:23
Message: <3625b2db.0@news.povray.org>
I wondered about this kind of situation too (material {} container use).
Seems the new method of "containing" both texture and interior together via 
the material keyword (totally unrelated to material_map) does not allow for 
pattern types to be used. So, interior items are not applicable to any form of 
patterning, only texture items. Ignore the messages about using interior items 
in finish as usual and you can still get there from here.
Just can't make "solid" insides of objects do the same.

Message <3624F6EC.F7CFF06F@skynet.be>, Hendrik Knaepen  typed...
>
>Hi,
>
>With POV-Ray3.02 I could make a color-dependant-refractive-surface using
>a texturemap with different filtered colors and different ior's.  Now
>that the ior has been moved to the interior, this is no longer
>possible.  At least not this way.  Is there another way to do this? And
>I mean directly from POV-Ray, so rendering the image a few times with
>changing refractions and colors is not what I want (it's too slow to do
>on my 486DX2 66 (Yeah, you may laugh, it has only 12Mb Ram! :-) )
>
>ZK
>
>--
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>     Hendrik Knaepen (hen### [at] skynetbe)
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>          Idee Software -- Vlaamse ShareWare
>            E-Mail: ide### [at] inamecom
>         WWW: http://www.surf.to/ideesoftware
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>  Bezoek ons voor gratis Nederlandstalige spellen!
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
>

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.html
=Bob


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From: Margus Ramst
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 05:39:23
Message: <3625B487.C30E8482@peak.edu.ee>
Hendrik Knaepen wrote:

> Hi,
>
> With POV-Ray3.02 I could make a color-dependant-refractive-surface using
> a texturemap with different filtered colors and different ior's.  Now
> that the ior has been moved to the interior, this is no longer
> possible.  At least not this way.  Is there another way to do this? And
> I mean directly from POV-Ray, so rendering the image a few times with
> changing refractions and colors is not what I want (it's too slow to do
> on my 486DX2 66 (Yeah, you may laugh, it has only 12Mb Ram! :-) )
>
> ZK

Heh, and I was whining about my 486DX4 120 and 16MB ;)

But about your question: as far as I see, varying ior is no longer possible
in 3.1. However, if U really need this, I saw a tutorial (_not_  a patch)
about adding dispersion to POV (I assume this is what U mean by
rainbow-refraction). It is at Daren Scot Wilson's page:
http://www.newcolor.com/darenw/DarenHome.html
Haven't tried this myself and U need to hack the source to do it, but
judging from the images it gives nice results.

Hope this helps...

Margus


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From: =Bob
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 12:19:12
Message: <36261270.0@news.povray.org>
I made a spectral dispersion include based upon Daren Wilsons example for P-R 
3.0*.
It's at http://members.aol.com/inversez/index.html in the Includes section.
I made simulated true wavelengths (by simulated here I mean they are somewhat 
relative among themselves according to actual wavelength in nature).
Choice of 6 or 12 wavelengths to use, with 12 being most realistic and 6 being 
fastest. I even added a fake infrared and ultraviolet possible so to blend at 
the ends. Not science in the least but it can look pretty convincing if 
variables are set up right. Btw, this only handles objects pigments as seen 
through the transparent texture, not light source colors; as many well know, 
lights do not have transmittance, as in reality. Only specular highlight, 
caustics and shadow.
I tried this out in POV-Ray 3.1 and didn't have any luck, but I did manage to 
use ior in the finish statement without an interior statement elsewhere with 
no problem. Seems use of any pattern is "lost".

Message <3625B487.C30E8482@peak.edu.ee>, Margus Ramst  typed...
>But about your question: as far as I see, varying ior is no longer possible
>in 3.1. However, if U really need this, I saw a tutorial (_not_  a patch)
>about adding dispersion to POV (I assume this is what U mean by
>rainbow-refraction). It is at Daren Scot Wilson's page:
>http://www.newcolor.com/darenw/DarenHome.html
>Haven't tried this myself and U need to hack the source to do it, but
>judging from the images it gives nice results.
>
>Hope this helps...
>
>Margus
>

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.html
=Bob


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From: Nieminen Mika
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 12:52:12
Message: <36261a2c.0@news.povray.org>
Hendrik Knaepen <hen### [at] skynetbe> wrote:
: (it's too slow to do
: on my 486DX2 66 (Yeah, you may laugh, it has only 12Mb Ram! :-) )

  My 486DX2 66 has only 8M of ram.
  The longest render ever was about 1 week. I have often rendered images
in 2-3 days.
  But mostly I render only images which take no more than a couple of
hours :)

-- 
                                                           - Warp. -


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From: Hendrik Knaepen
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 18:28:28
Message: <362668BB.B03518D0@skynet.be>
Nieminen Mika wrote:

> Hendrik Knaepen <hen### [at] skynetbe> wrote:
> : (it's too slow to do
> : on my 486DX2 66 (Yeah, you may laugh, it has only 12Mb Ram! :-) )
>
>   My 486DX2 66 has only 8M of ram.
>   The longest render ever was about 1 week. I have often rendered
> images
> in 2-3 days.
>   But mostly I render only images which take no more than a couple of
> hours :)
>
> --
>                                                            - Warp. -

The longest render I ever did would have been one of 5 days, but it took
too long to me, so I stopped it and started it over with far less
quality (still took about 10 hours!)
The rendering that used the most RAM, was one of a StarWars-scene.  It
needed about 57Mb Ram.  Lucky to me I had still about 1Gb free
disk-space for virtual-RAM.

I once heared it's sometimes better to make big and complicated objects
out of triangles.
Is this true? And will it only render faster, or will it also use less
memory?

ZK

--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
     Hendrik Knaepen (hen### [at] skynetbe)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
          Idee Software -- Vlaamse ShareWare
            E-Mail: ide### [at] inamecom
         WWW: http://www.surf.to/ideesoftware
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From: Mike
Subject: Re: rainbow-refraction
Date: 15 Oct 1998 22:32:12
Message: <3626AEAE.F1AF0D00@aol.com>
Triangles will use more memory, although a single mesh of triangles that is
copied many, many times only uses the amount of memory taken up by the
original.  I think just a few bytes are used to reference each copy.

Generally speaking, traiangles render faster than higher order polynomials
because they behave like a clipped plane.  I think they are only of the
first or second order.

Still, POV-Ray renders polynomials very fast, so it doesn't make so much
difference.

Here's an interesting factoid:  A triangle mesh exported from sPatch will
usually render faster than the same model exported as bezier patches, the
reason being the extra time it takes for POV-Ray to subdivide the patches
into triangles.  For those will memory contraints the bezier patches may be
the better way to go though.

-Mike


> I once heared it's sometimes better to make big and complicated objects
> out of triangles.
> Is this true? And will it only render faster, or will it also use less
> memory?
>
> ZK
>


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From: Hendrik Knaepen
Subject: Re: rainbow-refraction
Date: 16 Oct 1998 20:32:43
Message: <3627D75C.FA784959@skynet.be>
Margus Ramst wrote:

> Heh, and I was whining about my 486DX4 120 and 16MB ;)
>
> But about your question: as far as I see, varying ior is no longer
> possible
> in 3.1. However, if U really need this, I saw a tutorial (_not_  a
> patch)
> about adding dispersion to POV (I assume this is what U mean by
> rainbow-refraction). It is at Daren Scot Wilson's page:
> http://www.newcolor.com/darenw/DarenHome.html
> Haven't tried this myself and U need to hack the source to do it, but
> judging from the images it gives nice results.
>
> Hope this helps...
>
> Margus

Thanks, but I can't do this, since I haven't got a C-compiler.
And even if I had, I don't think I would do it, because I'm not very
good at programming and I don't like doing something while I don't know
what exactly I'm doing.
If I make a mistake, and it doesn't work, I spend more time searching
where the bug is than it's worth. (At least that's the way it goes often
when I try to program something in QB).

But I got an answer on the question: it's impossible to do with POV-Ray
as it is now.  Too bad.
Maybe color-dependant-refraction (or dispersion (nice word BTW; I didn't
know it had a name!) is a good thing to add on a future version (or a
patch).

ZK

--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
     Hendrik Knaepen (hen### [at] skynetbe)
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
          Idee Software -- Vlaamse ShareWare
            E-Mail: ide### [at] inamecom
         WWW: http://www.surf.to/ideesoftware
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
  Bezoek ons voor gratis Nederlandstalige spellen!
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=


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