 | | Mirror matrix question —Kevin L. Clague
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| | | 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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| | | | | Re: Mirror matrix question —Travis Cobbs
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| | | | | (This should probably have been in lugnet.cad.dev, and I almost put it there, but decided that it wouldn't make much difference.) I don't know the answer to this question. I'm responding any, just to let you know that I did read the question, since (...) (15 years ago, 15-Jun-09, to lugnet.cad)
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| | | | | Re: Mirror matrix question —Don Heyse
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| | | | | (...) I don't think so. (...) What if you mirror it again to get back to an unmirrored state, then run the code in mirwiz to create a submodel that only looks mirrored (but actually just flips pieces to look mirrored and substitutes opposite wedges, (...) (15 years ago, 15-Jun-09, to lugnet.cad)
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| | | | | Re: Mirror matrix question —Timothy Gould
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| | | | | (...) 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)
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| | | | | | | Re: Mirror matrix question —Kevin L. Clague
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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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| | | | | | | | Re: Mirror matrix question —Don Heyse
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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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| | | | | | | | Re: Mirror matrix question —Timothy Gould
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| | | | | | (...) --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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| | | | | Re: Mirror matrix question —Sergio Reano
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| | | | | (...) You can also use SR 3D Builder to build your mirrored/symmetric models. You build a side and the program will build the other, mirrored one. It automatically substitute and rotate non symmetric parts and is compatible with lDraw/MLCad file (...) (15 years ago, 15-Jun-09, to lugnet.cad)
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| | | | | Re: Mirror matrix question —Timothy Gould
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| | | | (...) Hi Kevin, I just realised that there might be a way to do this by exploiting the way LDRAW defines parts. All mirrored parts should be written as a bunch of studs and a subpart which is either mirrored or non-mirrored. By determining which (...) (15 years ago, 13-Aug-09, to lugnet.cad)
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