Subject:
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Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sun, 3 Oct 1999 02:57:45 GMT
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Viewed:
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797 times
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Gary and I wrote:
> > > I think there could be problems if some of those non-closed primitives are
> > > asymmetrical.
> >
> > Why?
>
> I'm having a difficult time picturing in my mind how an asymmetrical part
> can have its orientation matrix in the parent dat file mirrored and rotated
> (to flip the CW-ness of each polygon) and still have the same shape.
>
> Maybe I'm thinking of something totally different from what you're thinking.
> :/
OIC now. I think.
If an asymmetrical part is mirrored, it keeps the same shape, but is turned
inside out. To get it right-side-out again, it must be re-mirrored. In
other words, there's no way to produce left- and right-handed pairs of
asymmetrical primitives from a single primitive file, and maintain
C(C)W-ness. Is that what you mean?
In this case, a 0 INVERT meta-statement would be good. It would be a
signal to C(C)W-sensitive programs to invert their expectations.
Would it be better to make 0 INVERT affect just the next line, or to be
persistent? I'd prefer the second, but that's just my opinion.
Steve
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Message has 1 Reply:
 | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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| Steve Bliss wrote in message <37f4edd7.8510607@lu...et.com>... (...) are (...) rotated (...) thinking. (...) Possibly. I'm not to great when it comes to expressing myself. I think if an even number of mirror operations are performed on a part, its (...) (25 years ago, 3-Oct-99, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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| Steve Bliss wrote in message <37f4ab7d.64002272@l...et.com>... (...) Doh'! You're right. (...) I'm having a difficult time picturing in my mind how an asymmetrical part can have its orientation matrix in the parent dat file mirrored and rotated (to (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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