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Subject: 
Re: LDraw File Format Spec 1.0 DRAFT - MATRIX section updated
Newsgroups: 
lugnet.cad
Date: 
Tue, 11 Sep 2007 19:36:26 GMT
Viewed: 
4631 times
  
In lugnet.cad, Don Heyse wrote:
In lugnet.cad, Travis Cobbs wrote:
In lugnet.cad, Don Heyse wrote:
Hey, could you perhaps toss in the word "homogeneous" when describing that
matrix?  I tend to find more complete explanations when I add that to my
internet searches.

Before I do that, can someone tell me if a 3D transformation matrix that
includes shear is still homogeneous?

Yes, the matrix is still homogeneous.  In fact this page contains a nifty
explanation of how what we normally think of as a translation matrix is
actually a shear matrix where the extra w dimension added to make things
homogeneous is the fixed coordinate.

OK, I updated the first "4x4 3D transformation matrix" to now be "4x4
homogeneous transformation matrix".  I didn't feel that leaving 3D in there
somewhere was practical.  Because of this, I intentionally left the text alone
two sentences later, in the hopes that it would be helpful to people who aren't
up on the terminology.  I think that the result is OK, but it might be
confusing.

Thoughts?

--Travis



Message is in Reply To:
  Re: LDraw File Format Spec 1.0 DRAFT - MATRIX section updated
 
(...) Yes, the matrix is still homogeneous. In fact this page contains a nifty explanation of how what we normally think of as a translation matrix is actually a shear matrix where the extra w dimension added to make things homogeneous is the fixed (...) (17 years ago, 11-Sep-07, to lugnet.cad)

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