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Been fooling around with glows and ran across an interesting
property... negative colors can be used to cancel or shape the
halo.
I have included a trivial example where a negative green glow
cancels a positive one. This action is actually color-specific so
you can selectively allow different frequencies to pass or not
as required.
Not very exciting news perhaps, but it might be useful...
-------------------------------- snip --------------------------------
sphere { < 0, 0, -2000 > 1 pigment { rgb < 1, 1, 1 > } }
camera { location < 0, 0, -10 > look_at < 0, 0, 0 > }
/* positive */
glow
{
0.5
glow_type 0
color vnormalize( < 0, 1, 0 > )
location < -1, 0, 0 >
}
/* negative */
glow
{
0.5
glow_type 0
color vnormalize( < 0, -1, 0 > )
location < 1, 0, 0 >
}
-------------------------------- snip --------------------------------
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Download 'glow.jpg' (10 KB)
Preview of image 'glow.jpg'
![glow.jpg](/povray.binaries.images/attachment/%3C39ca9ba0%241%40news.povray.org%3E/glow.jpg?ttop=443840&toff=11850&preview=1)
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Useful. Hadn't thought of it. Thanks for the tip.
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"Spock" <spo### [at] nospam com> wrote :
>
> Been fooling around with glows and ran across an interesting
> property... negative colors can be used to cancel or shape the
> halo.
I've been playing with that too...
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Download 'Inverse03.jpg' (12 KB)
Preview of image 'Inverse03.jpg'
![Inverse03.jpg](/povray.binaries.images/attachment/%3C39cad1a5%40news.povray.org%3E/Inverse03.jpg?ttop=443840&toff=11850&preview=1)
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Spock <spo### [at] nospam com> wrote in message news:39ca9ba0$1@news.povray.org...
> Been fooling around with glows and ran across an interesting
> property... negative colors can be used to cancel or shape the
> halo.
Yup.. Kinda nifty. :{)
David
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Download 'glow_test2.jpg' (27 KB)
Preview of image 'glow_test2.jpg'
![glow_test2.jpg](/povray.binaries.images/attachment/%3C39cad878%40news.povray.org%3E/glow_test2.jpg?ttop=443840&toff=11850&preview=1)
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Doenst it affect the background?
ZK
http://www.povplace.be.tf
Spock <spo### [at] nospam com> schreef in berichtnieuws
39ca9ba0$1@news.povray.org...
> Been fooling around with glows and ran across an interesting
> property... negative colors can be used to cancel or shape the
> halo.
>
> I have included a trivial example where a negative green glow
> cancels a positive one. This action is actually color-specific so
> you can selectively allow different frequencies to pass or not
> as required.
>
> Not very exciting news perhaps, but it might be useful...
>
> -------------------------------- snip --------------------------------
> sphere { < 0, 0, -2000 > 1 pigment { rgb < 1, 1, 1 > } }
>
> camera { location < 0, 0, -10 > look_at < 0, 0, 0 > }
>
> /* positive */
> glow
> {
> 0.5
> glow_type 0
> color vnormalize( < 0, 1, 0 > )
> location < -1, 0, 0 >
> }
>
> /* negative */
> glow
> {
> 0.5
> glow_type 0
> color vnormalize( < 0, -1, 0 > )
> location < 1, 0, 0 >
> }
> -------------------------------- snip --------------------------------
>
>
>
>
>
>
Post a reply to this message
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On Thu, 21 Sep 2000 19:37:02 -0400, Spock wrote...
> Been fooling around with glows and ran across an interesting
> property... negative colors can be used to cancel or shape the
> halo.
>
> I have included a trivial example where a negative green glow
> cancels a positive one. This action is actually color-specific so
> you can selectively allow different frequencies to pass or not
> as required.
>
> Not very exciting news perhaps, but it might be useful...
I've also been playing with negative glows, but using radiosity...
The dark patch in the upper right corner of the image is a single
negative glow.
I was thinking that it might be useful in scenes where you want really
deep shadows in an otherwise well illumiated scene.
Bye for now,
Jamie.
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Download 'Neg_Glow_Rad.jpg' (37 KB)
Preview of image 'Neg_Glow_Rad.jpg'
![Neg_Glow_Rad.jpg](/povray.binaries.images/attachment/%3CMPG.1435be747ca720689897ea%40news.povray.org%3E/Neg_Glow_Rad.jpg?ttop=443840&toff=11850&preview=1)
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On Thu, 21 Sep 2000 19:37:02 -0400, Spock wrote:
>Been fooling around with glows and ran across an interesting
>property... negative colors can be used to cancel or shape the
>halo.
Hey Bob time to get that comet image out and have another go.
--
Cheers
Steve email mailto:ste### [at] zeropps uklinux net
%HAV-A-NICEDAY Error not enough coffee 0 pps.
web http://www.zeropps.uklinux.net/
or http://start.at/zero-pps
3:06pm up 31 days, 19:19, 1 user, load average: 2.05, 1.92, 1.48
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From: Tony[B]
Subject: Re: Negative Glow (36.3Kbu) - Neg_Glow_Rad.jpg [1/1]
Date: 22 Sep 2000 21:16:37
Message: <39cc0475@news.povray.org>
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Looks like a useful trick. This is good. Continue experimenting.
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On Fri, 22 Sep 2000 20:13:53 -0500, Tony[B] wrote...
> Looks like a useful trick. This is good. Continue experimenting.
The only problem is that I had to crank the radiosity settings up to
something ludicrous to get a halfway smooth render (Mainly because I
couldn't be bothered to go trawling through these groups to find the
settings that people have been posting :)
Bye for now,
Jamie.
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