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    Re: Mirror matrix question —Timothy Gould
   (...) Not sure if this helps but... If you solve (M11+1) x + M12 y = - M13 M21 x + (M22+1) y = - M23 and then normalise the vector (x,y,1) the result will be a vector normal to the mirroring plane. To test that you indeed have a rotation/mirror you (...) (15 years ago, 15-Jun-09, to lugnet.cad)
   
        Re: Mirror matrix question —Kevin L. Clague
   (...) 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)
   
        Re: Mirror matrix question —Don Heyse
   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)
   
        Re: Mirror matrix question —Timothy Gould
   (...) --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)
 

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