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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Thu, 30 Sep 1999 15:52:15 GMT
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Viewed:
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858 times
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Gary Williams <graywolf@pcpros.net> wrote in message
news:FIvo77.F2B@lugnet.com...
> John VanZwieten wrote in message ...
> > What I was concerned about are situations where a single quad is used as • the
> > outside of a section of a part and the inside of a section of a part. A
> > theoritical example would be a minifig head. You could use a single 4-
> > 4cyli.dat to model the outside of the top stud and the inside of the hole • in
> > the bottom, since they are the same diameter. Of course that would be bad
> > form.
>
>
> What if the part that referenced such a primitive had a '0 invert' comment
> on the line before the primitive reference, if that instance of the
> primitive was intended to appear inside-out?
In the case I'm talking about, 1 primitive is used in 1 instance to be both an
outer face and an inner face. In this case, you'd have to fix it manually by
using two primitives, one outer, and one inner.
As another example, consider a stair-step-like part, where a single quad could
be used as the top of one step and the bottom of the next step up.
Your idea for handling two instances of the same primitive would work.
Another, probably better, way would be to use mirroring to change the
CW/CCW-ness of the primitive to match the desired direction. For a primitive
like 2-4cyli.dat, you'd have to mirror and rotate the primitive to change the
CW-ness and still have the primitive function the same.
The key as I see it would be to automate this process, probably with your ray
tracing idea. Doing it by hand would be a real drag.
-John Van
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Message has 1 Reply:
 | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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| John VanZwieten wrote in message ... (...) primitive (...) the (...) ray (...) A hypothetical batch dat fixer program could examine the primitives first and flag the ones that were not closed volumes, since those would be the only ones that would (...) (25 years ago, 30-Sep-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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| John VanZwieten wrote in message ... (...) the (...) in (...) What if the part that referenced such a primitive had a '0 invert' comment on the line before the primitive reference, if that instance of the primitive was intended to appear inside-out? (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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