This effect was unexpected from my reading of the docs.

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In article <3fee4e88$1@news.povray.org> , "Greg M. Johnson" 
<gregj;-)565### [at] aolcom> wrote:

> This effect was unexpected from my reading of the docs.

No sample scene, no nothing?  What is this, a joke?  You do know better
after so many years of being around in these groups!

    Thorsten

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

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

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Thorsten Froehlich wrote:
> No sample scene, no nothing?  What is this, a joke?  You do know better
> after so many years of being around in these groups!

A priest, a minister, and a rabbi walk into a bar.  The bartender says,
"What is this, a joke?"

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On Sun, 28 Dec 2003 06:19:48 -0500, Tim Cook <z99### [at] bellsouthnet> wrote:

>A priest, a minister, and a rabbi walk into a bar.  The bartender says,
>"What is this, a joke?"

The clerics said "Ouch!"
Regards
        Stephen

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Not noticing anything in the documentation which suggests anything about it
besides the following line in section 9.1.1.1:

"It's a good idea to define both things, the light source and the looks_like
object, at the origin, and then translate them to their right place."

The example script at section 3.7.6.2 shows the light source being at
<0,2,0> whereas the looks_like object is at <0,0,0> (where an electric
filament might be), then it's placed by the light location vector.

I must concur with Thorsten, that referring us to something we could see
would help understand what descrepency is being observed, although I did
realize you were simply talking about the fact it gets relocated along with
the light's location vector.
I can't find anything specifically about this to quote from the doc and so
that would be a good thing to add, explaining about this particular
behavior, if it doesn't exist yet.

Bob H.

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// why does the position of the light at something other than the origin
// necessarily move the looks_like target object?

#declare greencyl=

cylinder{0,<0,180,0>,60
        texture{ pigment{green 1}        finish{reflection 0.3 phong 1  }}
        rotate 30*y
        no_shadow
        }

light_source{100*y green 1    looks_like { greencyl} translate -100*x}
light_source{50*y green 1    looks_like { greencyl} translate 100*x}



plane{y,0 pigment {rgb 1}}

camera {location<0,230,-500>  look_at 100*y  }

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> No sample scene, no nothing?  What is this, a joke?  You do know better
> after so many years of being around in these groups!

He wasn't giving a bug report; he was mentioning that something has been
left out of the documentation. Does he really need to provide a sample scene
to show that yes, in fact, the looks_like object is translated to the
light's position? A scene demonstrating how POV-Ray works is hardly
necessary to identify that the documentation doesn't completely describe its
behavior.

The only flaw I see in his post was that he relied on the subject line to
provide information which was necessary to understand it. Maybe that's what
confused you?

 - Slime
 [ http://www.slimeland.com/ ]

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Thanks for providing that Greg.  :-)

However... what I, myself, wondered about concerns the documentation having
or not having a correct example of this behavior. I thought it told
something incorrectly, based on what you posted at first, although it's
apparently only implied in the Doc through an example (which would need to
be rendered and understood somehow) and not discussed as to what looks_like
location affect has on light_source location (or vice versa). Other than to
say how defining objects for it at the origin could matter.

Simply stating any looks_like object follows light_source location would be
enough. And that should be told of in at least two places I believe, one
being the context help at 6.5.7.7 Looks_like and the other at 3.7.6.2
Assigning an Object to a Light Source. Elaborating, perhaps, that any
off-origin location of the defined object will still be used after being
invoked by looks_like.

Bob H.

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But I guess the bummer is that my object started at the origin, and its
volume included the point of the light source itself.
In thinking about this more, maybe the current pov-workings are the way
things ought to be, but I haven't made up my mind yet.

"Hughes, B." <omn### [at] charternet> wrote in message
news:3ff06bd8$1@news.povray.org...
>
> Thanks for providing that Greg.  :-)
> ...
> Elaborating, perhaps, that any
> off-origin location of the defined object will still be used after being
> invoked by looks_like.
>
> Bob H.
>
>

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In article <3fef75ea@news.povray.org> , "Slime" <fak### [at] emailaddress> wrote:

> He wasn't giving a bug report; he was mentioning that something has been
> left out of the documentation. Does he really need to provide a sample scene
> to show that yes, in fact, the looks_like object is translated to the
> light's position? A scene demonstrating how POV-Ray works is hardly
> necessary to identify that the documentation doesn't completely describe its
> behavior.

A scene showing what one wants to have explained really helps a lot, don't
you think so?  Especially if one does not really explain what one is talking
about ... and if you take a look at the scene later provided you will notice
that "looks_like moves", well, nothing!  The whole light source is moved
along with everything inside.

> The only flaw I see in his post was that he relied on the subject line to
> provide information which was necessary to understand it. Maybe that's what
> confused you?

No, not at all.

    Thorsten

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

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

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