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Subject: 
Re: LDraw File Format Spec 1.0 DRAFT - Call for Public Comments
Newsgroups: 
lugnet.cad
Date: 
Tue, 28 Aug 2007 20:43:52 GMT
Viewed: 
4418 times
  
In lugnet.cad, Kevin L. Clague wrote:
In lugnet.cad, Rob Ross wrote:

I think it would be helpful to mention the used matrix in line type 1 is
row orientated (more clearly then 'standard matrix').

Just my thoughts,

Roland

Is this really what the LDRAW spec is stating? Because that would be contrary to
the OpenGL spec, in which the standard ordering of matrices is column-major.

So if you have a row like

a b c d e f g h

That would be interpreted in OpenGL as

a e
b f
c g
d h

and NOT

a b c d
e f g h


Rob

Hi Rob,
  Not to be indelicate, but LDraw was around *before* OpenGL.  That said, I
  think the document *must* explicitly show something like this:

Let me restate the above.....because I think I'm wrong about the timeline.

LDraw is a stand alone specification, so what OpenGL expects is not relevent.
The LDraw specification must specify what its coordinate and matricies formats
mean, especially when derived from a string of numbers all on one line.


a b c
d e f
g h i

Furthermore I think the document must explain x, y and z.  If I remember
correctly above the origin, y is negative.

Kevin



Message has 1 Reply:
  Re: LDraw File Format Spec 1.0 DRAFT - Call for Public Comments
 
(...) I agree, and believe that both my proposed "sample matrices" as well as Tim's "transformation equation" will go into the final spec. --Travis (17 years ago, 28-Aug-07, to lugnet.cad)

Message is in Reply To:
  Re: LDraw File Format Spec 1.0 DRAFT - Call for Public Comments
 
(...) Hi Rob, Not to be indelicate, but LDraw was around *before* OpenGL. That said, I think the document *must* explicitly show something like this: a b c d e f g h i Furthermore I think the document must explain x, y and z. If I remember correctly (...) (17 years ago, 28-Aug-07, to lugnet.cad)

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