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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Fri, 1 Oct 1999 17:12:22 GMT
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Viewed:
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973 times
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John VanZwieten wrote:
>
> > > I agree with John Van in that we need three keywords: CCW, CW, UNKNOWN.
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>
> I'm not so sure about this anymore. I think the ideal would be a program that
> could change the part files so that they are completely CCW. Using the
> raytracing method and enough computer time, he should be able to identify
> whether each quad complies with CCW. If a quad doesn't comply, then the
> program should rearrange the vertices. If a quad is out of compliance but is
> part of a primitive, then the program should mirror and rotate the primitive
> so that it complies. The part would then be given the 0 CCW Compliant tag
> which would let the rendering program know it could perform backface culling
> on that part. Even if the most basic parts, like baseplates, plates, and
> rectangular bricks could be brought into compliance, the time savings could be
> considerable.
If we know that a face is CW, why not change it to CCW ? The most
difficult task is to discover the orientation of a face, but once we
have that information anyone can change the order of the points and fix
the face.
> In some cases, like stud2.dat, the primitive file should be altered first so
> that it is internally CCW compliant.
This can be done easily, I already have correct stud primitives but I
inlined them.
> If such a utility program could be created, it would take the burden off part
> authors to worry about ordering their vertices correctly.
I had a program that could show the CCW faces in green and the CW
faces red, and the user could move through the faces and press space to
change the order of the points, with a little more work this could be
turned into a better program and part authors could use it to check
their parts before submiting for voting. Of course, having a program
that does all the work automatically would be much better :)
Leonardo
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Message has 1 Reply:
 | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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| (...) why can't you simply mod your proggy to handle the conversion automatically?? i mean.. if your proggy is smart enough to detect uninified normals and then allows the user to press a key to mod the CW/CCW property of the face, why can't you (...) (25 years ago, 1-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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| Jacob Sparre Andersen <sparre@sys-323.risoe.dk> wrote in message news:FIxHC0.E2v@lugnet.com... (...) I'm not so sure about this anymore. I think the ideal would be a program that could change the part files so that they are completely CCW. Using (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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