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Does anyone know how to generate an inverse matrix. By inverse I mean it will
undo the rotation of the original matrix. I thought the inverse of
<1,0,0,0,1,0,0,0,1,0,0,0> was <-1,0,0,0,-1,0,0,0,-1,0,0,0>. In other words,
multiply every value by -1.
I know POV-Ray 3.6 has an inverse matrix function but it doesn't work in 3.1,
which is what I'm using.
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Message has 3 Replies:
 | | Re: Inverse matrix?
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| (...) The inverse of <1,0,0,0,1,0,0,0,1,0,0,0> is itself. To compute the inverse of a general 3x3 matrix (essentially what you need to do) is rather complicated. You could do it in a macro using Gaussian elimination [1]. Tim [1] (URL) (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | Re: Inverse matrix?
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| (...) There really is no easy way to do it. Feel free to look at TCVector::invertMatrix in the LDView code if you want to see code that does it on a 4x4 matrix. To convert a 3x3 matrix into a 4x4 matrix, put the 3x3 in the top left, put a 1 in the (...) (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
| | | Re: Inverse matrix?
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| (...) I just realised something... do you want a general inverse or a specific inverse? Some inversions are simple eg. a pure rotation can be inverted by taking its transpose and reflections are their own inverses. Tim (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
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