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Subject: 
Re: LDraw File Format Spec 1.0 DRAFT - MATRIX section updated
Newsgroups: 
lugnet.cad
Date: 
Tue, 11 Sep 2007 19:09:00 GMT
Viewed: 
4441 times
  
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.

  http://www.blancmange.info/notes/maths/vectors/homo/

Pretty neat, eh?

Enjoy,

Don



Message has 1 Reply:
  Re: LDraw File Format Spec 1.0 DRAFT - MATRIX section updated
 
(...) 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, (...) (17 years ago, 11-Sep-07, to lugnet.cad)

Message is in Reply To:
  Re: LDraw File Format Spec 1.0 DRAFT - MATRIX section updated
 
(...) Before I do that, can someone tell me if a 3D transformation matrix that includes shear is still homogeneous? If not, then I'm not going to put it in. --Travis (17 years ago, 11-Sep-07, to lugnet.cad)

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