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Special: 
[DAT] (requires LDraw-compatible viewer)
Subject: 
Re: Another matrix inverse question
Newsgroups: 
lugnet.cad
Date: 
Wed, 11 Apr 2007 04:36:40 GMT
Viewed: 
2044 times
  
In lugnet.cad, Brian Durney wrote:
handL xform
  0.98543465  -0.17005472  0.0  0.0
  0.12024684  0.6968075  0.70710677  0.0
  -0.12024684  -0.6968075  0.70710677  0.0
  23.558212  25.872986  -10.0  1.0

You might want to check your row/column order for the converted code from
LDView.  At least conceptually, I always invision transformation matrices like
so:

A B C X
D E F Y
G H I Z
0 0 0 1

Notice that the translation info is in the last column, not the last row like
your example.  The offsets in the LDView code map like so:

0  4  8 12
1  5  9 13
2  6 10 14
3  7 11 15

--Travis



Message is in Reply To:
  Re: Another matrix inverse question
 
(...) I can see the advantages of swapping the off-diagonals for inverting the rotation(s), but that still leaves the question of how to invert translations. In a current example I'm looking at, a minifig hand, the hand is rotated 45 degrees, (...) (18 years ago, 11-Apr-07, to lugnet.cad)

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