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 23:46:27 GMT
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Viewed:
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611 times
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In lugnet.cad.ray, James Reynolds wrote:
> 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
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
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Message has 1 Reply:
Message is in Reply To:
 | | Re: Inverse matrix?
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| Clarification! .... snip (...) 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] (...) (18 years ago, 7-Apr-07, to lugnet.cad.ray, lugnet.cad)
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