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Special: 
[DAT] (requires LDraw-compatible viewer)
Subject: 
Re: Object Orientation & DAT files & CLIPPING/WINDING
Newsgroups: 
lugnet.cad.dev
Date: 
Tue, 19 Oct 1999 13:25:53 GMT
Viewed: 
1669 times
  
Steve Bliss wrote in message <380b3366.9260126@lugnet.com>...
> >  Now the INVERT problem: • [snip]
> >  NOTE:
> >  if you had a non simetrical object, you will probably need an invert
> >  matrix (with a negative determinant), besides the INVERT meta command.
> 
> You'll always need to specify the inversion in the matrix, whether the
> subfile is asymmetrical or not.  The matrix specifies the exact inversion
> to perform.  The 0 INVERT is just a flag to the renderer, which says "Hey,
> rendering program! The next statement intentionally turns the subfile
> inside-out, so don't correct it."


No, you don't need to bother with the matrix. Use the 0 INVERT to tell
the renderer: "Hey, please turn the following subfiles inside-out".
Remember the example from stud2.dat:
  1 16 0 -4 0 4 0 0 0 4 0 0 0 4 4-4cyli.dat
  0 INVERT ON
  1 16 0 -4 0 6 0 0 0 4 0 0 0 6 4-4cyli.dat
  0 INVERT OFF
See also http://www.lugnet.com/news/display.cgi?lugnet.cad.dev:2956

Apart from that I fully agree with Steve's comments to Rui.
/Lars



Message has 1 Reply:
  Re: Object Orientation & DAT files & CLIPPING/WINDING
 
(...) Yes the coded inversion is needed, for one big reason: The clipping-ready parts library must be compatible with non-clipping rendering programs, such as LDraw. So the inversions need to occur in the real commands, not in the clipping-extension (...) (27 years ago, 19-Oct-99, to lugnet.cad.dev)

Message is in Reply To:
  Re: Object Orientation & DAT files & CLIPPING/WINDING
 
(...) These are all assumptions/specifications which *should* be agreed upon by the L-CAD community, especially parts-authors and rendering program-writers. Agreement is only needed if we want to re-wire the parts library, to encourage (...) (27 years ago, 18-Oct-99, to lugnet.cad.dev)

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