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  Q : double_illuminate propagation in CSG's (Message 1 to 5 of 5)  
From: Michael Andrews
Subject: Q : double_illuminate propagation in CSG's
Date: 21 Jun 2000 07:39:34
Message: <3950A986.C7FEF9B8@reading.ac.uk>
Hi Folks,

Can someone check me on this behaviour? In the doc's for Megapov (0.5a)
it states that double_illuminate is used in the same way as hollow and
no_shadow. As I recall, hollow and no_shadow propagate down a CSG so
that

union {
  object { ... }
  object { ... }
  texture { ... }
  hollow
}

makes both objects hollow, the same as writing

union {
  object { ... hollow }
  object { ... hollow }
  texture { ... }
}

and no_shadow behaves in the same fashion.

However, when double_illuminate is used in the same way the first syntax
does _not_ seem to produce objects that double_illuminate.

I've only looked at unions so I don't know if this applies to the other
CSG types. I would guess it does. So the question is, _should_
double_illuminate propagate down the CSG tree? Or do the doc's simply
need changing to stste that it does not propagate and you must
explicitly set this flag for each object in a CSG?

Bye for now,
	Mike Andrews.


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From: Warp
Subject: Re: Q : double_illuminate propagation in CSG's
Date: 21 Jun 2000 08:43:51
Message: <3950b887@news.povray.org>
Michael Andrews <M.C### [at] readingacuk> wrote:
: CSG types. I would guess it does. So the question is, _should_
: double_illuminate propagate down the CSG tree?

  I think it should. That way it would be consistent with the other similar
keywords.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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From: SamuelT
Subject: Re: Q : double_illuminate propagation in CSG's
Date: 21 Jun 2000 13:09:25
Message: <3950F79F.621903AF@aol.com>
Hi Michael. I ran into this problem just yesterday when I tried to get two
triangles to have double-illumination inside a union. I had to put
double_illuminate in both triangle statements, because I could not find any
other workaround.


Michael Andrews wrote:

> Hi Folks,
>
> Can someone check me on this behaviour? In the doc's for Megapov (0.5a)
> it states that double_illuminate is used in the same way as hollow and
> no_shadow. As I recall, hollow and no_shadow propagate down a CSG so
> that
>
> union {
>   object { ... }
>   object { ... }
>   texture { ... }
>   hollow
> }
>
> makes both objects hollow, the same as writing
>
> union {
>   object { ... hollow }
>   object { ... hollow }
>   texture { ... }
> }
>
> and no_shadow behaves in the same fashion.
>
> However, when double_illuminate is used in the same way the first syntax
> does _not_ seem to produce objects that double_illuminate.
>
> I've only looked at unions so I don't know if this applies to the other
> CSG types. I would guess it does. So the question is, _should_
> double_illuminate propagate down the CSG tree? Or do the doc's simply
> need changing to stste that it does not propagate and you must
> explicitly set this flag for each object in a CSG?
>
> Bye for now,
>         Mike Andrews.


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From: Nathan Kopp
Subject: Re: double_illuminate propagation in CSG's
Date: 21 Jun 2000 17:28:11
Message: <3951336b$1@news.povray.org>
Michael Andrews <M.C### [at] readingacuk> wrote...
> Hi Folks,
>
> Can someone check me on this behaviour? In the doc's for Megapov (0.5a)
> it states that double_illuminate is used in the same way as hollow and
> no_shadow.

> However, when double_illuminate is used in the same way the first syntax
> does _not_ seem to produce objects that double_illuminate.

This has been noted.  I'll fix it (eventually, but don't count on anything
really soon because I'm swamped) so that double_illuminate copied to
children of CSG objects.

-Nathan


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From: Michael Andrews
Subject: Re: double_illuminate propagation in CSG's
Date: 22 Jun 2000 05:27:41
Message: <3951DC1D.FF7E39D4@reading.ac.uk>
Hi Nathan,

Nathan Kopp wrote:
> 
> This has been noted.  I'll fix it (eventually, but don't count on anything
> really soon because I'm swamped) so that double_illuminate copied to
> children of CSG objects.
> 
> -Nathan

No worry, no hurry :-)

Knowing about the behaviour I can easily work around it. If you have the
time it might be worth updating the documentation to show the current
behaviour. This won't break any scenes when the behaviour is eventually
fixed, since it will still be back-compatible with the current
behaviour.

Thanks to all for the replies,
	Mike Andrews.


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