I read the docs many times, but couldn't find any reference to this
behaviour: light_sources inside a light_group do not cast shadows.

#declare Location = <0, 2, -4>;
#declare Look_at = <0, 0, 0>;

camera
{
  location  Location
  look_at   Look_at
}


#declare Thing=
text {ttf "arialbd.ttf" "TEXT" 1,0 pigment {rgb 1} translate -x-z/2}

light_group {

light_source
{ <-4, 0, -5>
  rgb 1.5
}

object {Thing}
torus {1.75,0.25 pigment {rgb 1}}

}



--
Jonathan.

Post a reply to this message

JRG wrote:
> 
> I read the docs many times, but couldn't find any reference to this
> behaviour: light_sources inside a light_group do not cast shadows.

> light_group {
> 
> light_source
> { <-4, 0, -5>
>   rgb 1.5
> }
> 
> object {Thing}
> torus {1.75,0.25 pigment {rgb 1}}
> 
> }

Your objects are part of the light_group.
I would expect light_group to behave as the old 'look_like'
extension: no self-shadow on the group.

Try putting your objects OUTSIDE of the light_group, it should work.

Post a reply to this message

I'm sorry, but it doesn't make sense to me... :(
By definition, the lightsources inside a lightgroup should light only the
objects in the lightgroup. If I want them not to cast shadows I'll put a
no_shadow flag.

--
Jonathan.

"Jérôme Grimbert" <jer### [at] atosorigincom> ha scritto nel messaggio
news:3BF### [at] atosorigincom...
> JRG wrote:
> >
> > I read the docs many times, but couldn't find any reference to this
> > behaviour: light_sources inside a light_group do not cast shadows.
>
> > light_group {
> >
> > light_source
> > { <-4, 0, -5>
> >   rgb 1.5
> > }
> >
> > object {Thing}
> > torus {1.75,0.25 pigment {rgb 1}}
> >
> > }
>
> Your objects are part of the light_group.
> I would expect light_group to behave as the old 'look_like'
> extension: no self-shadow on the group.
>
> Try putting your objects OUTSIDE of the light_group, it should work.

Post a reply to this message

"JRG" <jrg### [at] hotmailcom> wrote in message
news:3bfe98ed@news.povray.org...
> I'm sorry, but it doesn't make sense to me... :(
> By definition, the lightsources inside a lightgroup should light only the
> objects in the lightgroup. If I want them not to cast shadows I'll put a
> no_shadow flag.

I believe the confusion here might be that the objects won't cast a shadow
onto things outside of the particular light group.  Is that what you were
seeing?  Or are you saying that you do not see any shadows on objects from
other objects all within a certain light group?

Hmm, I've rendered your test scene and I get a shadow across the text coming
from the torus.  I thought you were not seeing shadows on a background plane
or something, so what I'm seeing here is actually expected.

What I would question as to what is expected or not is the following:

#declare Location = <0, 2, -4>;
#declare Look_at = <0, 0, 0>;

camera
{
  location  Location
  look_at   Look_at
}

#declare Thing=
text {ttf "arialbd.ttf" "TEXT" 1,0 pigment {rgb 1} translate -x-z/2}

light_group {

light_source
{ <-4, 0, -5>
  rgb 1.5
}

object {Thing}

} // end group

torus {1.75,0.25 pigment {rgb 1}} // makes shadow

In this case a person might be thinking they could shine the light through
any objects not contained within a particular light group.  Instead, it
still casts a shadow.

Bob H.

Post a reply to this message

Bob H wrote:
> Hmm, I've rendered your test scene and I get a shadow across the text
coming
> from the torus

Really?! Well, I don't (both compiles). I get that shadow only if I comment
out the light_group.

POV-Ray v3.5 Windows ME Athlon.

--
Jonathan.

Post a reply to this message

"JRG" <jrg### [at] hotmailcom> wrote in message
news:3bff576a@news.povray.org...
> Bob H wrote:
> > Hmm, I've rendered your test scene and I get a shadow across the text
> coming
> > from the torus
>
> Really?! Well, I don't (both compiles). I get that shadow only if I
comment
> out the light_group.
>
> POV-Ray v3.5 Windows ME Athlon.

Wouldn't that be strange if it's due to the Athlon processor...?
I didn't change a thing from your example script and the torus shadow
certainly crossed the text from halfway up to the lowest part.  Just to
clarify that.

Bob H.

Post a reply to this message

I don't get shadows either. Can't be the Athlon.

Marc-Hendrik

PII 450, Win98, 128 MB, Pov 3.5 beta 7.icl

Bob H. schrieb in Nachricht <3bff6344@news.povray.org>...

>Wouldn't that be strange if it's due to the Athlon processor...?
>I didn't change a thing from your example script and the torus shadow
>certainly crossed the text from halfway up to the lowest part.  Just to
>clarify that.
>
>Bob H.
>
>
>

Post a reply to this message

In article <3bff6344@news.povray.org> , "Bob H." <omn### [at] msncom> wrote:

> "JRG" <jrg### [at] hotmailcom> wrote in message
> news:3bff576a@news.povray.org...
>> Bob H wrote:
>> > Hmm, I've rendered your test scene and I get a shadow across the text
>> coming
>> > from the torus
>>
>> Really?! Well, I don't (both compiles). I get that shadow only if I
>> comment
>> out the light_group.
>>
>> POV-Ray v3.5 Windows ME Athlon.
>
> Wouldn't that be strange if it's due to the Athlon processor...?
> I didn't change a thing from your example script and the torus shadow
> certainly crossed the text from halfway up to the lowest part.  Just to
> clarify that.

I can reproduce this.  Below is a simpler version without all the
unnecessary declares and a font one can find on othere systems as well.

camera
{
  location  <0, 2, -4>
  look_at   <0, 0, 0>
}

light_group {
 light_source
 {
  <0, 5, -3>
  rgb 1
 }

 text {ttf "times.ttf" "TEXT" 1,0 pigment {rgb 1} translate <-1,1,-2>}
 torus {1.75,0.25 pigment {rgb 1}}
}


____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

"Thorsten Froehlich" <tho### [at] trfde> wrote in message
news:3bff6ec3$1@news.povray.org...
>
> I can reproduce this.  Below is a simpler version without all the
> unnecessary declares and a font one can find on other systems as well.

Okay, are you saying I should not be seeing a shadow of the text falling
onto the torus, or that it does?  I do see the shadow.
In case this is going to matter, my system is Intel P3 with WinXP.

Bob H.

> camera
> {
>   location  <0, 2, -4>
>   look_at   <0, 0, 0>
> }
>
> light_group {
>  light_source
>  {
>   <0, 5, -3>
>   rgb 1
>  }
>
>  text {ttf "times.ttf" "TEXT" 1,0 pigment {rgb 1} translate <-1,1,-2>}
>  torus {1.75,0.25 pigment {rgb 1}}
> }
>
>
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
>
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

I've posted the image showing the problem to beta-test.binaries.

--
Jonathan.

Post a reply to this message

I got it. If you turn light buffers off it works fine. So it must be a bug.

--
Jonathan.

Post a reply to this message

"JRG" <jrg### [at] hotmailcom> wrote in message
news:3bffaa2f@news.povray.org...
> I got it. If you turn light buffers off it works fine. So it must be a
bug.

Yes, must be.  Especially since I can use either -ul or +ul.  Light buffer
on or off is the same for me here.

Post a reply to this message

Not for me: with +ul the bug manifests itself, with -ul it doesn't. It's
really strange...
Maybe light buffers work unexpectedly in XP? I mean, there's a bug, but with
XP it doesn't show. Any other XP users here?

--
Jonathan.


"Bob H." <omn### [at] msncom> ha scritto nel messaggio
news:3bffac25@news.povray.org...
> "JRG" <jrg### [at] hotmailcom> wrote in message
> news:3bffaa2f@news.povray.org...
> > I got it. If you turn light buffers off it works fine. So it must be a
> bug.
>
> Yes, must be.  Especially since I can use either -ul or +ul.  Light buffer
> on or off is the same for me here.
>
>
>

Post a reply to this message

In article <3bffadd0@news.povray.org> , "JRG" <jrg### [at] hotmailcom> wrote:

> Maybe light buffers work unexpectedly in XP? I mean, there's a bug, but with
> XP it doesn't show. Any other XP users here?

The core code does not depend on the operating system (besides, one thing is
for sure: I am not using WinDOS XP).  Don't jump to such conclusions.  There
are a million reasons why it cannot work, none of which has to do with the
operating system.  Only the source code can tell...

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

Wasn't it Marc-Hendrik Bremer who wrote:

>I don't get shadows either. Can't be the Athlon.

I'm going to log this as a confirmed bug, even though I'm not entirely
sure of the conditions under which the shadows are present.

On my system there are no shadows in either of the examples posted.

Here's my, rather confusing, contribution to the fray - no text object,
just spheres and boxes for simplicity.



camera { location  <0, 2, -3>
         look_at   0
}
    
light_group {
  light_source { <-1, 3, 1> rgb 1}
  sphere {y,0.5 pigment {rgb 1}}
  box {<-1,0,-1><1,0.5,1> pigment {rgb 1}}
}

//  sphere {<4,-5,10>,0.5 pigment {rgb 1}}

background {rgb z}



On my machine, as written, the sphere casts a shadow on the box.
However, when I uncomment the second sphere the shadow disappears. The
existence of any extra object seems to switch off the shadow. Even if
the second sphere is moved inside the light group it kills the shadow.

3.5b7 (both versions), Celeron II 800, W98se, 128Mb

-- 
Mike Williams
Gentleman of Leisure

Post a reply to this message

Mike Williams schrieb ...

>On my machine, as written, the sphere casts a shadow on the box.
>However, when I uncomment the second sphere the shadow disappears. The
>existence of any extra object seems to switch off the shadow. Even if
>the second sphere is moved inside the light group it kills the shadow.
>

I can confirm this behavior with your script. It is cured by using -ul in
this case, too.

Marc-Hendrik

PII450, Win98, 128 MB, Pov 3.5 beta 7

Post a reply to this message

Of course, my fault. Sorry.

--
Jonathan.
"Thorsten Froehlich" <tho### [at] trfde> ha scritto nel messaggio
news:3bffbaac@news.povray.org...
> In article <3bffadd0@news.povray.org> , "JRG" <jrg### [at] hotmailcom> wrote:
>
> > Maybe light buffers work unexpectedly in XP? I mean, there's a bug, but
with
> > XP it doesn't show. Any other XP users here?
>
> The core code does not depend on the operating system (besides, one thing
is
> for sure: I am not using WinDOS XP).  Don't jump to such conclusions.
There
> are a million reasons why it cannot work, none of which has to do with the
> operating system.  Only the source code can tell...
>
>     Thorsten
>
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
>
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message