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1 Nov 2024 14:20:40 EDT (-0400)
  Reflection across a plane.. (Message 1 to 6 of 6)  
From: Kalloran
Subject: Reflection across a plane..
Date: 2 Jul 2008 12:00:01
Message: <web.486ba53f166e4d9d1143938a0@news.povray.org>
Been playing with various aspects of POV-ray: manipulations of simple geometric
shapes and such.  The one BASIC geometric transformation that I cannot find a
command for is reflection.  The simple reflection of a geometric shape across a
plane.  For instance, I'm if I'm creating a complex, but symmetrical object,
should I not be able to only create half then reflect it across, say, the xy
plane?  Any help in locating this command (if it exists) would be awesome.
Thanks.


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From: Chris B
Subject: Re: Reflection across a plane..
Date: 2 Jul 2008 12:21:03
Message: <486baaef$1@news.povray.org>
"Kalloran" <nomail@nomail> wrote in message 
news:web.486ba53f166e4d9d1143938a0@news.povray.org...
> Been playing with various aspects of POV-ray: manipulations of simple 
> geometric
> shapes and such.  The one BASIC geometric transformation that I cannot 
> find a
> command for is reflection.  The simple reflection of a geometric shape 
> across a
> plane.  For instance, I'm if I'm creating a complex, but symmetrical 
> object,
> should I not be able to only create half then reflect it across, say, the 
> xy
> plane?  Any help in locating this command (if it exists) would be awesome.
> Thanks.

You can scale using a negative number, so:

  object {MyCSGObject scale <-1,1,1>}

creates a copy of your object mirrored in the YZ plane and scale <1,1,-1> 
will mirror in the XY plane

ps. 'reflection' tends to refer to the 'finish' attribute in a texture 
definition with POV-Ray.

Regards,
Chris B.


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From: Warp
Subject: Re: Reflection across a plane..
Date: 2 Jul 2008 12:23:19
Message: <486bab77@news.povray.org>
Kalloran <nomail@nomail> wrote:
> Been playing with various aspects of POV-ray: manipulations of simple geometric
> shapes and such.  The one BASIC geometric transformation that I cannot find a
> command for is reflection.  The simple reflection of a geometric shape across a
> plane.  For instance, I'm if I'm creating a complex, but symmetrical object,
> should I not be able to only create half then reflect it across, say, the xy
> plane?  Any help in locating this command (if it exists) would be awesome.
> Thanks.

  What you can do if you have modelled, for example, exactly half of the
object so that it lies, for example on the yz plane on either one side of
it, and you want to copy it mirrored in the x direction, is:

#declare HalfObject = ...the half of the object...;
#declare WholeObject =
  union
  { object { HalfObject }
    object { HalfObject scale <-1, 1, 1> }
  }

-- 
                                                          - Warp


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From: Kalloran
Subject: Re: Reflection across a plane..
Date: 2 Jul 2008 13:05:00
Message: <web.486bb451a30a738f1143938a0@news.povray.org>
Thanks a bunch!  Yeah, i know reflection refers to a finish....hence why I was
having a hard time finding any assistance out of the help menu.


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From: Warp
Subject: Re: Reflection across a plane..
Date: 2 Jul 2008 13:42:29
Message: <486bbe05@news.povray.org>
Kalloran <nomail@nomail> wrote:
> Thanks a bunch!  Yeah, i know reflection refers to a finish....hence why I was
> having a hard time finding any assistance out of the help menu.

  Maybe mirroring would be a better term. (OTOH that probably isn't any
better of a search keyword for the documentation... :P )

-- 
                                                          - Warp


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From: Chris B
Subject: Re: Reflection across a plane..
Date: 2 Jul 2008 15:58:41
Message: <486bddf1@news.povray.org>
"Warp" <war### [at] tagpovrayorg> wrote in message 
news:486bbe05@news.povray.org...
> Kalloran <nomail@nomail> wrote:
>> Thanks a bunch!  Yeah, i know reflection refers to a finish....hence why 
>> I was
>> having a hard time finding any assistance out of the help menu.
>
>  Maybe mirroring would be a better term. (OTOH that probably isn't any
> better of a search keyword for the documentation... :P )
>
> -- 
>                                                          - Warp

Actually I don't recall ever seeing it documented anywhere. Maybe it's a 
good candidate for the wiki and/or the FAQ.

Chris B.


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