POV-Ray : Newsgroups : povray.beta-test : Hollow Planes Server Time
13 Nov 2024 01:57:03 EST (-0500)
  Hollow Planes (Message 1 to 4 of 4)  
From: Topher
Subject: Hollow Planes
Date: 17 Sep 2001 13:42:03
Message: <3ba635eb$1@news.povray.org>
I was trying to use some fog in my scene and no matter where I put my
camera, the compiler always said it was inside a non-hollow object. I
finally got it to stop when I added the "hollow" key word to the plane
object.

Is this a bug or what?


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From: Trevor Quayle
Subject: Re: Hollow Planes
Date: 17 Sep 2001 13:56:41
Message: <3ba63959$1@news.povray.org>
"Topher" <top### [at] descentbbnet> wrote in message
news:3ba635eb$1@news.povray.org...
> I was trying to use some fog in my scene and no matter where I put my
> camera, the compiler always said it was inside a non-hollow object. I
> finally got it to stop when I added the "hollow" key word to the plane
> object.
>
> Is this a bug or what?
>
>

No
Read 6.5.3.1

-tgq


--
camera{location z*13look_at 0}light_source{15 15looks_like{sphere{0 10
}pigment{rgb 1}finish{ambient 15}}}union{torus{3,0.5rotate x*90}cone{y
*4,.5,-y*8,0}cone{-x*4,.5,x*8,0}pigment{rgb<.7,.6,.4>}finish{ambient 0
diffuse 0reflection{1fresnel on metallic 1}}interior{ior 25}rotate 15}
plane{y,-7pigment{checker rgb 0rgb 1scale 4}finish{diffuse.1}}//   TGQ


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From: Matthew Walton
Subject: Re: Hollow Planes
Date: 17 Sep 2001 18:13:39
Message: <3BA676CC.1020804@alledora.co.uk>
Topher wrote:

> I was trying to use some fog in my scene and no matter where I put my
> camera, the compiler always said it was inside a non-hollow object. I
> finally got it to stop when I added the "hollow" key word to the plane
> object.
> 
> Is this a bug or what?


No bug - POV's done that for as long as I can remember (since at least 
version 3.0). Planes have one side that's considered "inside" it and one 
side that's considered "outside" it. I think the "inside" is the side 
that's opposite to the normal vector you use to define it, hence for a 
plane {y,0}, the "inside" would be anything where y<0.


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From: Warp
Subject: Re: Hollow Planes
Date: 17 Sep 2001 20:08:11
Message: <3ba6906b@news.povray.org>
Think about a plane as an infinite box. It helps understanding why one
side is "inside" and the other "outside". In one side you are inside the box,
while in the other you are outside.

-- 
#macro N(D,I)#if(I<6)cylinder{M()#local D[I]=div(D[I],104);M().5,2pigment{
rgb M()}}N(D,(D[I]>99?I:I+1))#end#end#macro M()<mod(D[I],13)-6,mod(div(D[I
],13),8)-3,10>#end blob{N(array[6]{11117333955,
7382340,3358,3900569407,970,4254934330},0)}//                     - Warp -


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