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  hollow in light groups (Message 1 to 7 of 7)  
From: Trevor Quayle
Subject: hollow in light groups
Date: 19 Dec 2001 10:04:58
Message: <3c20ac9a$1@news.povray.org>
Couldn't find this in the docs or in a previous posting.


the 'hollow' keyword doesn't seem to work properly in light groups.

if you put the camera inside an object with hollow it renders fine
if you out the hollow object inside a light group, you get the 'camera is
inside a non-hollow object..." warning.

-tgq


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From: Thorsten Froehlich
Subject: Re: hollow in light groups
Date: 19 Dec 2001 13:34:01
Message: <3c20dd99@news.povray.org>
In article <3c20ac9a$1@news.povray.org> , "Trevor Quayle" 
<Tin### [at] hotmailcom> wrote:

> Couldn't find this in the docs or in a previous posting.
>
>
> the 'hollow' keyword doesn't seem to work properly in light groups.
>
> if you put the camera inside an object with hollow it renders fine
> if you out the hollow object inside a light group, you get the 'camera is
> inside a non-hollow object..." warning.

Please provide a _short_ example.


    Thorsten


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From: TinCanMan
Subject: Re: hollow in light groups
Date: 19 Dec 2001 17:39:41
Message: <3c21172d$1@news.povray.org>
> Please provide a _short_ example.

Odd, I'm not sure what's going on here.
Try the following scene, the camera is not inside the box but is inside the
sphere

1) as is, the scene gives an error even though the camera is inside the
sphere and the sphere is 'hollow' and not inside the box.
2)comment out just the sphere and it's fine
3)comment out just the box and it's fine
4) add 'hollow' to the box and it's fine (the camera isn't even in the box)
5) move just the box outside the light group and it's fine
6) move just the sphere outside the light group and it's fine

hope this helps

-tgq


//start
camera{
  location <50,30,50>
  look_at  <0,0,0>
}

light_group{
  box{<-300,-30,-120> <300,-5.5,120>}
  plane{-y 0 hollow}
}
//end


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From: Mike Williams
Subject: Re: hollow in light groups
Date: 20 Dec 2001 08:42:58
Message: <Y++xgGATlVI8Ew5O@econym.demon.co.uk>
Wasn't it TinCanMan who wrote:
>> Please provide a _short_ example.
>
>Odd, I'm not sure what's going on here.
>Try the following scene, the camera is not inside the box but is inside the
>sphere
>
>1) as is, the scene gives an error even though the camera is inside the
>sphere and the sphere is 'hollow' and not inside the box.
>2)comment out just the sphere and it's fine
>3)comment out just the box and it's fine
>4) add 'hollow' to the box and it's fine (the camera isn't even in the box)
>5) move just the box outside the light group and it's fine
>6) move just the sphere outside the light group and it's fine

It looks to me like the program needs to determine whether the whole
light_group is hollow or not, and it's doing it in the same way that it
does it for CSG. In a union or merge, the resulting CSG object is hollow
only if *all* the parts are hollow. I.e. substituting "union" or "merge"
for "light_group" in your code gives exactly the same effect.

-- 
Mike Williams
Gentleman of Leisure


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From: Thorsten Froehlich
Subject: Re: hollow in light groups
Date: 20 Dec 2001 09:17:05
Message: <3c21f2e1$1@news.povray.org>
In article <Y++xgG### [at] econymdemoncouk> , Mike Williams 
<mik### [at] nospamplease>  wrote:

> only if *all* the parts are hollow. I.e. substituting "union" or "merge"
> for "light_group" in your code gives exactly the same effect.

Yes, because a light_group internally is a (special) union...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: Trevor Quayle
Subject: Re: hollow in light groups
Date: 20 Dec 2001 09:26:42
Message: <3c21f522$1@news.povray.org>
"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3c21f2e1$1@news.povray.org...
> In article <Y++xgG### [at] econymdemoncouk> , Mike Williams
> <mik### [at] nospamplease>  wrote:
>
> > only if *all* the parts are hollow. I.e. substituting "union" or "merge"
> > for "light_group" in your code gives exactly the same effect.
>
> Yes, because a light_group internally is a (special) union...
>
>     Thorsten

So the 'hollow' in the sphere is ignored because the box isn't hollow?

-tgq


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From: Thorsten Froehlich
Subject: Re: hollow in light groups
Date: 20 Dec 2001 12:32:44
Message: <3c2220bc@news.povray.org>
In article <3c21f522$1@news.povray.org> , "Trevor Quayle" 
<Tin### [at] hotmailcom> wrote:

> So the 'hollow' in the sphere is ignored because the box isn't hollow?

Actually, it might be that only the check fails and everything works the way
it is supposed to.  In a future beta light_group unions will automatically
be split and the message will no long appear.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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