Hello,
  When I use double_illuminate in a radiosity scene it does nothing (it 
does get double_illuminated by light_sources).
Here's a scene to illustrate:

default{finish{ambient 0}}
camera{location <3,4,5> look_at 0}
polygon{5,x,y,-x,-y,x pigment{rgb 1}double_illuminate translate  z}
polygon{5,x,y,-x,-y,x pigment{rgb 1}double_illuminate translate -z}
background{rgb z}
global_settings{radiosity{}}
sphere{-y/2,0.5 texture{pigment{rgb y}finish{ambient 10 diffuse 0}}}
light_source{y/2,rgb x}

Is it a bug or it is intentional?

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Jan Dvorak <jan### [at] centrumcz> wrote:
> Hello,
>   When I use double_illuminate in a radiosity scene it does nothing (it
> does get double_illuminated by light_sources).
> Here's a scene to illustrate:
>
> Is it a bug or it is intentional?

it's not a bug!  There are no light sources in pure radiosity, so you shouldn't
expect an object to get "doubly illuminated".  Use at least one light_source
together with radiosity.

It's the same for reflection:  no light_sources, no reflection.

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nemesis wrote:
> It's the same for reflection:  no light_sources, no reflection.
> 
	?? Where did you see that? There is absolutely no relation between
light sources and reflections, and you *can* still get reflections
even if there are no light sources. Are you sure you didn't mean
"photons"?

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
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nemesis nous apporta ses lumieres en ce 2007/11/11 12:28:
> Jan Dvorak <jan### [at] centrumcz> wrote:
>> Hello,
>>   When I use double_illuminate in a radiosity scene it does nothing (it
>> does get double_illuminated by light_sources).
>> Here's a scene to illustrate:
>>
>> Is it a bug or it is intentional?
> 
> it's not a bug!  There are no light sources in pure radiosity, so you shouldn't
> expect an object to get "doubly illuminated".  Use at least one light_source
> together with radiosity.
> 
> It's the same for reflection:  no light_sources, no reflection.
> 
> 
> 
You can always see an object with a high ambient value in a reflection without 
any light.
Not the case with photons. No light_source = no photons.

-- 
Alain
-------------------------------------------------
Real Time, adj.:
     Here and now, as opposed to fake time, which only occurs there
and then.

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Alain napsal(a):
> nemesis nous apporta ses lumieres en ce 2007/11/11 12:28:
>> Jan Dvorak <jan### [at] centrumcz> wrote:
>>> Hello,
>>>   When I use double_illuminate in a radiosity scene it does nothing (it
>>> does get double_illuminated by light_sources).
>>> Here's a scene to illustrate:
>>>
>>> Is it a bug or it is intentional?
>>
>> it's not a bug!  There are no light sources in pure radiosity, so you 
>> shouldn't
>> expect an object to get "doubly illuminated".  Use at least one 
>> light_source
>> together with radiosity.
>>
>> It's the same for reflection:  no light_sources, no reflection.
>>
>>
>>
> You can always see an object with a high ambient value in a reflection 
> without any light.
> Not the case with photons. No light_source = no photons.
> 
I use a plain white background + radiosity to light the scene. Or I use 
a blue gradient and a yellowish light_source.

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I would expect the front square to be illuminated by the green sphere 
(ambient 10) in the example scene.

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Alain <ele### [at] netscapenet> wrote:
> You can always see an object with a high ambient value in a reflection without
> any light.

oh!  but that *is* a bug! :P

or presumibly the high ambient object is considered a light source?

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=?ISO-8859-1?Q?=22J=E9r=F4me_M=2E_Berger=22?= <jeb### [at] freefr> wrote:
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> nemesis wrote:
> > It's the same for reflection:  no light_sources, no reflection.
> >
>  ?? Where did you see that? There is absolutely no relation between
> light sources and reflections, and you *can* still get reflections
> even if there are no light sources. Are you sure you didn't mean
> "photons"?

no, I meant reflections:  if there are no light sources, reflections *shouldn't*
be seen anywhere.  If there are no light rays, what is tracing the reflective
images?

I remember lighting some test scene with pure radiosity and reflective materials
and getting no reflections at all.  And it sounds ok to me.

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nemesis napsal(a):
> Alain <ele### [at] netscapenet> wrote:
>> You can always see an object with a high ambient value in a reflection without
>> any light.
> 
> oh!  but that *is* a bug! :P
> 
> or presumibly the high ambient object is considered a light source?
> 
Yes. And that's the only way to make a solid object shine, AFAIK.

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nemesis wrote:
> =?ISO-8859-1?Q?=22J=E9r=F4me_M=2E_Berger=22?= <jeb### [at] freefr> wrote:
>> nemesis wrote:
>>> It's the same for reflection:  no light_sources, no reflection.
>>>
>>  ?? Where did you see that? There is absolutely no relation between
>> light sources and reflections, and you *can* still get reflections
>> even if there are no light sources. Are you sure you didn't mean
>> "photons"?
> 
> no, I meant reflections:  if there are no light sources, reflections *shouldn't*
> be seen anywhere.  If there are no light rays, what is tracing the reflective
> images?
> 
	In that case, if there are no light rays, what is tracing the
image? You should see a pure black image, which obviously you don't.

> I remember lighting some test scene with pure radiosity and reflective materials
> and getting no reflections at all.  And it sounds ok to me.
> 
	I'd be really interested to see such a scene if you could make one,
but you can't (unless you use the "no_reflection" keyword of
course). I have made some test scenes with pure ambient lighting
(neither light sources nor radiosity) and reflective materials and
the reflections showed just fine.

		Jerome
- --
+------------------------- Jerome M. BERGER ---------------------+
|    mailto:jeb### [at] freefr      | ICQ:    238062172            |
|    http://jeberger.free.fr/     | Jabber: jeb### [at] jabberfr   |
+---------------------------------+------------------------------+
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