Subject:
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Re: Mirror matrix question
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Newsgroups:
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lugnet.cad
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Date:
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Tue, 16 Jun 2009 03:49:17 GMT
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Viewed:
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9362 times
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In lugnet.cad, Don Heyse wrote:
> Hi Kevin,
--snip--
> But maybe it doesn't really matter. Perhaps you can just pick *any*
> mirror axis you like, and undo it. What's left is the rotation matrix
> that goes with that mirror op. I can't prove it though. Sorry...
>
> Don
You are right here. In 3D it gets a bit more complicated and, as far as I know,
a mirror and rotation corresponds to a mirroring on a plane and a rotation
within that plane.
I'm sure there is a way to unravel it all but it's almost certainly not unique
and is probably an unstable process.
As far as software is concerned the best solution would just be to ask people to
make the mirrored section a separate submodel and then rotate the submodel. It's
one of those cases where the user can do it all more safely and sensibly than
the software.
Tim
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Message is in Reply To:
 | | Re: Mirror matrix question
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| Hi Kevin, Here's the problem. A mirror plus a rotation can look just like a mirror across another axis. Ugly 2D ASCII art example: .|b --- .|. Mirror the b to the left. d|. --- .|. Rotate 180 degrees. .|. --- .|p That looks just like you mirrored (...) (15 years ago, 15-Jun-09, to lugnet.cad)
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