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From: Mike Horvath
Subject: looks_like suggestion
Date: 8 Sep 2016 04:46:20
Message: <57d0ed1c$1@news.povray.org>
http://www.povray.org/documentation/view/3.6.2/137/

On this page it says:

"It is 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."

However, this is *not* a good idea for parallel light sources. Doing so 
causes the light to emit from the light source's original position (the 
origin) instead of the later position.


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 04:49:26
Message: <57d0edd6$1@news.povray.org>
On 9/8/2016 12:46 AM, Mike Horvath wrote:
> http://www.povray.org/documentation/view/3.6.2/137/
>
> On this page it says:
>
> "It is 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."
>
> However, this is *not* a good idea for parallel light sources. Doing so
> causes the light to emit from the light source's original position (the
> origin) instead of the later position.

Oops. I didn't realize the reference was for an old versions of POV-Ray. 
I have no idea if the newer reference has fixed this mistake or not.

Mike


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 04:58:37
Message: <57d0effd$1@news.povray.org>
On 9/8/2016 12:46 AM, Mike Horvath wrote:
> http://www.povray.org/documentation/view/3.6.2/137/
>
> On this page it says:
>
> "It is 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."
>
> However, this is *not* a good idea for parallel light sources. Doing so
> causes the light to emit from the light source's original position (the
> origin) instead of the later position.

http://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_4_1_7

This section only shows an example of how *not* to properly set up the 
looks_like section. It should explain how to do it *correctly* too. But 
I don't know what is correct.


Mike


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From: Alain
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 21:14:53
Message: <57d1d4cd@news.povray.org>
Le 16-09-08 à 00:58, Mike Horvath a écrit :
> On 9/8/2016 12:46 AM, Mike Horvath wrote:
>> http://www.povray.org/documentation/view/3.6.2/137/
>>
>> On this page it says:
>>
>> "It is 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."
>>
>> However, this is *not* a good idea for parallel light sources. Doing so
>> causes the light to emit from the light source's original position (the
>> origin) instead of the later position.
>
> http://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_4_1_7
>
> This section only shows an example of how *not* to properly set up the
> looks_like section. It should explain how to do it *correctly* too. But
> I don't know what is correct.
>
>
> Mike

The looks_like object is always centered at the light's location.
So, you should create your light_source at any location while 
constructing the looks_like object around the origin.


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From: Mike Horvath
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 22:07:29
Message: <57d1e121$1@news.povray.org>
On 9/8/2016 5:15 PM, Alain wrote:
> Le 16-09-08 à 00:58, Mike Horvath a écrit :
>> On 9/8/2016 12:46 AM, Mike Horvath wrote:
>>> http://www.povray.org/documentation/view/3.6.2/137/
>>>
>>> On this page it says:
>>>
>>> "It is 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."
>>>
>>> However, this is *not* a good idea for parallel light sources. Doing so
>>> causes the light to emit from the light source's original position (the
>>> origin) instead of the later position.
>>
>> http://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_4_1_7
>>
>> This section only shows an example of how *not* to properly set up the
>> looks_like section. It should explain how to do it *correctly* too. But
>> I don't know what is correct.
>>
>>
>> Mike
>
> The looks_like object is always centered at the light's location.
> So, you should create your light_source at any location while
> constructing the looks_like object around the origin.
>
>


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.

Mike


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From: clipka
Subject: Re: looks_like suggestion
Date: 8 Sep 2016 22:28:51
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 22:51:09
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 12:40:40
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 13:45:19
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 14:22:54
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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