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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Mon, 15 Jun 2009 06:43:50 GMT
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Viewed:
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8642 times
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In lugnet.cad, Kevin L. Clague wrote:
> Hi gang,
>
> If I have an LDraw Type 1 line that adds a submodel, and the rotation matrix
> of the line is a mirrored matrix about one and only one axis, can one calculate
> which axis the model is mirrored about? Can one do so if the user mirrored
> *and* rotated the submodel when adding it to the model?
>
> What I want to do is to be able to render the mirror image version of the
> model as the mirror image (so the user builds the submodel correctly), but with
> the same overall orientation as the non-mirrored version.
>
> Any help would be great.
>
> Thanks,
> Kevin
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 can check
that
M31 x + M32 y = -(M33+1)
to required precision.
Tim
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Message has 1 Reply:
 | | Re: Mirror matrix question
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| (...) 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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Message is in Reply To:
| | Mirror matrix question
|
| Hi gang, If I have an LDraw Type 1 line that adds a submodel, and the rotation matrix of the line is a mirrored matrix about one and only one axis, can one calculate which axis the model is mirrored about? Can one do so if the user mirrored *and* (...) (15 years ago, 14-Jun-09, to lugnet.cad)
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