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Subject: 
Re: Some Words To BFC
Newsgroups: 
lugnet.cad.dev
Date: 
Tue, 4 Apr 2000 13:56:02 GMT
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Leonardo Zide <leonardo@centroin.com.br> wrote in message
news:38E9EDA0.2C97D944@centroin.com.br...
Michael Lachmann wrote:

My suggestion is to keep the BFC statements as simple as possible. • Meaning we
should rather correct wrong defined
parts than letting the software correct wrong definitions!!!!

  That's why I droped out of the BFC discussion a long time ago, we are
making this a big issue with proposals for a new extension when we could
make things much simpler.

  If you know that a part is wrong, instead of adding a "0 INVERSE"
statement (or whatever you call it now) you just change the orientation,
I guess that Steve should be able to add a command that inverts the
sequence of points of a quad/tri to LDAO easily (if he has enough free
time). This way a program will only have to check for inverse matrixes
on files that are outside the ldraw/parts directory.


It's not just a matter of knowing that a part is "wrong" and fixing it.  The
problem is primitives where either the inner faces or the outer faces may
constitute the outside of a part.  The box5.dat is a perfect example used in
many basic parts.  When used for the top side of a brick, it is correctly
oriented.  When used for the under side or "inside" of a brick the winding is
improper.  That's a case where you use a "0 Inverted" tag on the under side
box5 to note that it's used inside-out.

Of course we do have the option of creating a whole new set of primitives,
but I think we wanted to avoid that option.  Also discussed was the option of
rotating an inside-out primitive and inverting it, but someone found problems
with that idea as well.

-John Van



Message has 1 Reply:
  Re: Some Words To BFC
 
(...) If the matrix for the box5 inside the part is inverted, wouldn't it work ? Leonardo (24 years ago, 4-Apr-00, to lugnet.cad.dev)

Message is in Reply To:
  Re: Some Words To BFC
 
(...) That's why I droped out of the BFC discussion a long time ago, we are making this a big issue with proposals for a new extension when we could make things much simpler. If you know that a part is wrong, instead of adding a "0 INVERSE" (...) (24 years ago, 4-Apr-00, to lugnet.cad.dev)  

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