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Subject: 
Re: Mirror matrix question
Newsgroups: 
lugnet.cad
Date: 
Mon, 15 Jun 2009 16:22:52 GMT
Viewed: 
9211 times
  
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 the original b downward.


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



Message has 1 Reply:
  Re: Mirror matrix question
 
(...) --snip-- (...) 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 (...) (15 years ago, 16-Jun-09, to lugnet.cad)

Message is in Reply To:
  Re: Mirror matrix question
 
(...) Hi Tim, Thanks. Math is not my specialty, so all help is appreciated. If the user has rotated the mirrored submodel, doesn't the vector normal then also get rotated? The hope was there was a way to separate the mirrored aspect of the rotation (...) (15 years ago, 15-Jun-09, to lugnet.cad)

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