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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683 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:
 | | 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 (...) (23 years ago, 10-Feb-02, to lugnet.cad.dev)
| | | 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 (...) (23 years ago, 11-Feb-02, to lugnet.cad.dev)
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Message is in Reply To:
| | 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' (...) (23 years ago, 10-Feb-02, to lugnet.cad.dev)
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