Subject:
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Re: Inverse matrix?
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Newsgroups:
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lugnet.cad.ray, lugnet.cad
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Date:
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Sat, 7 Apr 2007 23:29:19 GMT
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Viewed:
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608 times
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Clarification!
.... snip
> This way I have a matrix that will rotate any object using a lookat
> and up.
I am using additional points to specify the location of feet.
Combined with the model location, I have 3 points for the hip and
feet. [now the following paragraph should make more sense]
> However, I'm trying to use these points to construct a walking
> motion so I have at least 3 points for a model all in world
> coordinates. To figure out the rotations of the model's legs I
> need to convert these to the model's local coordinates. To move
> the points to local model coordinates I just have to subtract the
> model location from all the points. But now I have to undo the
> world rotation. I'm stumped. I've tried tons of stuff and I
> thought this wouldn't be so hard and quite frankly this math is a
> bit over my head.
>
> I'm sure I can do this using "a particular system of linear
> equations", but I honestly don't know which. I've tried many
> different things but nothing gets me the results I need.
>
> Does anyone have any ideas?
>
> James
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Message has 1 Reply:
 | | Re: Inverse matrix?
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| (...) Just take the transpose of the 3x3 world rotation matrix and it should work as the inverse. Transpose means swap diagonals M[1,2] <=> M[2,1] etc. If this doesn't work I've misunderstood you. Tim (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
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Message is in Reply To:
| | Re: Inverse matrix?
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| (...) Arg. I thought this was going to be easy. I liked this part of the wikipedia article: "In practice, inverting a matrix is rarely required. Most of the time, one is really after the solution of a particular system of linear equations." Hm. I (...) (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
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