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Subject: 
Re: Object Orientation & DAT files & CLIPPING/WINDING
Newsgroups: 
lugnet.cad.dev
Date: 
Tue, 19 Oct 1999 21:38:21 GMT
Viewed: 
1776 times
  
On Tue, 19 Oct 1999 13:25:53 GMT, "Lars C. Hassing" <lch@ccieurope.com>
wrote:

> 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".

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 meta-commands.

Now, if you want to talk about having a special version of the parts
library just for clipping-ready renderers, let's go!  But in a separate
thread, please.

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

Seems like there was an echo in here, eh? ;)  My earlier reply looked a lot
like yours.

Steve



Message has 1 Reply:
  Re: Object Orientation & DAT files & CLIPPING/WINDING  [DAT]
 
Steve Bliss wrote... (...) "Hey, (...) But it *is* compatible with LDraw! You left out my example (which BTW had the INVERT placed incorrectly :-), so I'll repeat it. stud2.dat is the hollow stud used on technic bricks. It uses two cylinders: 1 16 0 (...) (27 years ago, 20-Oct-99, to lugnet.cad.dev)

Message is in Reply To:
  Re: Object Orientation & DAT files & CLIPPING/WINDING  [DAT]
 
Steve Bliss wrote in message <380b3366.9260126@lu...et.com>... (...) 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 (...) (27 years ago, 19-Oct-99, to lugnet.cad.dev)

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