Subject:
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Re: A comprehensive LDraw object model
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sun, 10 Feb 2002 06:55:21 GMT
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Viewed:
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586 times
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In lugnet.cad.dev, Kyle McDonald writes:
> Actually this brings up a different issue. I haven't put alot of thought
> into it yet, but I think it would be useful to add information in the
> part files that would allow a program to differentiate between geometry
> that represents 'outside' walls and features, and 'inside' walls and
> features.
IIRC (and I wish I could find the reference) the LDraw spec does support this.
It depends on the order of the points in the polygon; e.g. clockwise points
out, counterclockwise points in. Or something like that.
But last I heard of this, there were a lot of LDraw parts that had
improperly-coded lines, so I dunno what the state of the whole thing is.
Backface culling or BFC? Is that what I was remembering? Arg. Something
the parts authors were talking about, anyway...
Cheers,
- jsproat
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Message has 2 Replies: ![](/news/x.gif) | | Re: A comprehensive LDraw object model
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| (...) Backface culling (BFC) is what you are describing, but it isn't what Kyle was asking for :-). In traditional realtime 3D rendering, polygons only have one side. The back side is literally non-existent. It doesn't get drawn at all. This is (...) (22 years ago, 10-Feb-02, to lugnet.cad.dev)
| ![](/news/x.gif) | | Re: A comprehensive LDraw object model
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| (...) Yes, What you're describing does sound like BFC to me. As someone else (travis I think?) said, BFC is a useful optimiziation for reducing the number of surfaces that need to be drawn. But it's not the same thing I was talking about. BFC (...) (22 years ago, 11-Feb-02, to lugnet.cad.dev)
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Message is in Reply To:
![](/news/x.gif) | | Re: A comprehensive LDraw object model
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| (...) Actually this brings up a different issue. I haven't put alot of thought into it yet, but I think it would be useful to add information in the part files that would allow a program to differentiate between geometry that represents 'outside' (...) (22 years ago, 10-Feb-02, to lugnet.cad.dev)
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30 Messages in This Thread: ![A comprehensive LDraw object model -Jeremy H. Sproat (9-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/246.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (9-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/246.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/246.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Bernd Broich (12-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Bernd Broich (16-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -James Reynolds (12-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (12-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (7-May-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/268.gif) ![Re: A comprehensive LDraw object model -James Reynolds (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/268.gif) ![Re: A comprehensive LDraw object model -Larry Pieniazek (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -Bernd Broich (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/246.gif) ![Re: A comprehensive LDraw object model -Travis Cobbs (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -Bernd Broich (11-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/268.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Jeremy H. Sproat (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/268.gif) ![Re: A comprehensive LDraw object model -Michael Horvath (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (10-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/246.gif) ![You are here](/news/here.gif) ![](/news/246.gif) ![Re: A comprehensive LDraw object model -Travis Cobbs (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (11-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Anders Isaksson (11-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Kyle McDonald (11-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/28.gif) ![](/news/x.gif) ![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -Steve Bliss (11-Feb-02 to lugnet.cad.dev)](/news/x.gif) ![](/news/46.gif) ![Re: A comprehensive LDraw object model -Michael Horvath (11-Feb-02 to lugnet.cad.dev)](/news/x.gif)
![](/news/x.gif) ![](/news/68.gif) ![Re: A comprehensive LDraw object model -Jacob Sparre Andersen (10-Feb-02 to lugnet.cad.dev)](/news/x.gif)
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