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18 May 2022 15:55:45 EDT (-0400)
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From: clipka
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 18:28:51
Message: <57d1e623@news.povray.org>
Am 09.09.2016 um 00:07 schrieb Mike Horvath:
> Can I update the wiki page with the additional information? I already
> have a wiki account, and am logged in, but the article is locked.

You should be able to post the suggested new wording on the respective
"Discussion" page; if it's ok, Jim can copy it from there.


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 18:51:09
Message: <57d1eb5d$1@news.povray.org>
On 9/8/2016 6:28 PM, clipka wrote:
> Am 09.09.2016 um 00:07 schrieb Mike Horvath:
>> Can I update the wiki page with the additional information? I already
>> have a wiki account, and am logged in, but the article is locked.
>
> You should be able to post the suggested new wording on the respective
> "Discussion" page; if it's ok, Jim can copy it from there.
>

Okay, I suggested my changes here:

http://wiki.povray.org/content/Reference_Talk:Light_Source


Mike


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From: Jim Holsenback
Subject: Re: looks_like suggestion
Date: 11 Sep 2016 08:40:40
Message: <57d550c8$1@news.povray.org>
On 9/8/2016 6:51 PM, Mike Horvath wrote:
> On 9/8/2016 6:28 PM, clipka wrote:
>> Am 09.09.2016 um 00:07 schrieb Mike Horvath:
>>> Can I update the wiki page with the additional information? I already
>>> have a wiki account, and am logged in, but the article is locked.
>>
>> You should be able to post the suggested new wording on the respective
>> "Discussion" page; if it's ok, Jim can copy it from there.
>>
>
> Okay, I suggested my changes here:

Well that section was awkward to begin with ... since it was so short I 
just rewrote the whole thing:

http://wiki.povray.org/content/Reference:Light_Source#Looks_Like

I also renamed /that/ and one other section for consistency reasons


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From: clipka
Subject: Re: looks_like suggestion
Date: 11 Sep 2016 09:45:19
Message: <57d55fef$1@news.povray.org>
Am 11.09.2016 um 14:40 schrieb Jim Holsenback:

> Well that section was awkward to begin with ... since it was so short I
> just rewrote the whole thing:
> 
> http://wiki.povray.org/content/Reference:Light_Source#Looks_Like

I find "important things to consider" item 5 quite confusing: Is it
intended to apply to a regular looks_like object, or the union alternative?

Personally I'm quite sure it's the latter, but I would suggest to
instead use wording like:

    4. use a union instead if you want the object to
       block light (remember to make /some/ portion of
       the object transparent)

Also, the union example is broken, as in contrast to looks_like the
union doesn't auto-translate My_Lamp_Shape to the location of the light
source.


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From: Jim Holsenback
Subject: Re: looks_like suggestion
Date: 11 Sep 2016 10:22:54
Message: <57d568be$1@news.povray.org>
On 9/11/2016 9:45 AM, clipka wrote:
> Am 11.09.2016 um 14:40 schrieb Jim Holsenback:
>
>> Well that section was awkward to begin with ... since it was so short I
>> just rewrote the whole thing:
>>
>> http://wiki.povray.org/content/Reference:Light_Source#Looks_Like
>
> I find "important things to consider" item 5 quite confusing: Is it
> intended to apply to a regular looks_like object, or the union alternative?

well the union example of course! i DID have "and ..." as #4 then "..." 
at the beginning of #5

LOL ... fixed it

>
> Personally I'm quite sure it's the latter, but I would suggest to
> instead use wording like:
>
>     4. use a union instead if you want the object to
>        block light (remember to make /some/ portion of
>        the object transparent)
>
> Also, the union example is broken, as in contrast to looks_like the
> union doesn't auto-translate My_Lamp_Shape to the location of the light
> source.

done and done


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 11 Sep 2016 10:23:24
Message: <57d568dc$1@news.povray.org>
On 9/11/2016 8:40 AM, Jim Holsenback wrote:
> On 9/8/2016 6:51 PM, Mike Horvath wrote:
>> On 9/8/2016 6:28 PM, clipka wrote:
>>> Am 09.09.2016 um 00:07 schrieb Mike Horvath:
>>>> Can I update the wiki page with the additional information? I already
>>>> have a wiki account, and am logged in, but the article is locked.
>>>
>>> You should be able to post the suggested new wording on the respective
>>> "Discussion" page; if it's ok, Jim can copy it from there.
>>>
>>
>> Okay, I suggested my changes here:
>
> Well that section was awkward to begin with ... since it was so short I
> just rewrote the whole thing:
>
> http://wiki.povray.org/content/Reference:Light_Source#Looks_Like
>
> I also renamed /that/ and one other section for consistency reasons
>


Looks_like works fine with parallel lights as long as you position the 
light correctly to start off with instead of placing it at the origin 
and then translating it at some later time.

Unless I made a mistake.


Mike


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From: clipka
Subject: Re: looks_like suggestion
Date: 11 Sep 2016 13:55:42
Message: <57d59a9e$1@news.povray.org>
Am 11.09.2016 um 16:23 schrieb Mike Horvath:

> Looks_like works fine with parallel lights as long as you position the
> light correctly to start off with instead of placing it at the origin
> and then translating it at some later time.
> 
> Unless I made a mistake.

Judging from the code, I see no reason why that should make any difference.


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From: Jim Holsenback
Subject: Re: looks_like suggestion
Date: 12 Sep 2016 06:45:53
Message: <57d68761$1@news.povray.org>
On 9/11/2016 1:55 PM, clipka wrote:
> Am 11.09.2016 um 16:23 schrieb Mike Horvath:
>
>> Looks_like works fine with parallel lights as long as you position the
>> light correctly to start off with instead of placing it at the origin
>> and then translating it at some later time.
>>
>> Unless I made a mistake.
>
> Judging from the code, I see no reason why that should make any difference.
>

Pulled directly from the previous version of this section:

"For point lights and spotlights you could also place the light source 
and the looks_like object at the origin and translate them together 
later. But for parallel lights this will not work."

Did I get it wrong? Just trying to honor what was previously mentioned!


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From: clipka
Subject: Re: looks_like suggestion
Date: 12 Sep 2016 07:56:10
Message: <57d697da$1@news.povray.org>
Am 12.09.2016 um 12:45 schrieb Jim Holsenback:
> On 9/11/2016 1:55 PM, clipka wrote:
>> Am 11.09.2016 um 16:23 schrieb Mike Horvath:
>>
>>> Looks_like works fine with parallel lights as long as you position the
>>> light correctly to start off with instead of placing it at the origin
>>> and then translating it at some later time.
>>>
>>> Unless I made a mistake.
>>
>> Judging from the code, I see no reason why that should make any
>> difference.
>>
> 
> Pulled directly from the previous version of this section:
> 
> "For point lights and spotlights you could also place the light source
> and the looks_like object at the origin and translate them together
> later. But for parallel lights this will not work."
> 
> Did I get it wrong? Just trying to honor what was previously mentioned!

I can't say for sure at the moment. All I can say is that I didn't find
anything in the code that would explain that wording, but I might have
overlooked something. I guess experiments may be needed.

Maybe the sentence was placed there not so much due to unexpected
effects on the looks_like object, but unexpected effects on the light
source itself. (For instance, whether or wheter not POV-Ray translates
the `point_at` location along with the parallel light source, either way
the effect may be surprising to some users.)


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 12 Sep 2016 10:43:37
Message: <57d6bf19$1@news.povray.org>
On 9/12/2016 7:56 AM, clipka wrote:
> Am 12.09.2016 um 12:45 schrieb Jim Holsenback:
>> On 9/11/2016 1:55 PM, clipka wrote:
>>> Am 11.09.2016 um 16:23 schrieb Mike Horvath:
>>>
>>>> Looks_like works fine with parallel lights as long as you position the
>>>> light correctly to start off with instead of placing it at the origin
>>>> and then translating it at some later time.
>>>>
>>>> Unless I made a mistake.
>>>
>>> Judging from the code, I see no reason why that should make any
>>> difference.
>>>
>>
>> Pulled directly from the previous version of this section:
>>
>> "For point lights and spotlights you could also place the light source
>> and the looks_like object at the origin and translate them together
>> later. But for parallel lights this will not work."
>>
>> Did I get it wrong? Just trying to honor what was previously mentioned!
>
> I can't say for sure at the moment. All I can say is that I didn't find
> anything in the code that would explain that wording, but I might have
> overlooked something. I guess experiments may be needed.
>
> Maybe the sentence was placed there not so much due to unexpected
> effects on the looks_like object, but unexpected effects on the light
> source itself. (For instance, whether or wheter not POV-Ray translates
> the `point_at` location along with the parallel light source, either way
> the effect may be surprising to some users.)
>


I posted a test scene in p.t.s-f.


Mike


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