Subject:
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Re: Non-colanar quads question
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Newsgroups:
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lugnet.cad.dat.parts
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Date:
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Tue, 13 Jul 2004 20:09:57 GMT
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Viewed:
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3187 times
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In lugnet.cad.dat.parts, William Howard wrote:
> I'm fixing the Perl code that generates the curved surface of the Half [1] Onion
> Dome (part 44511) from its control data.
>
> At the moment the surface comprises counter-clockwise wound quads
> (ABCD) [3] and conditional lines (AB, BC, CD and DA). However, all
> the quads are non-coplanar.
> If I've worked it out correctly [4], I can replace all the quads with
> triangles (ABC and ACD).
Be careful with that. You could also replace it with triangles
(ABD and DBC) using the other diagonal. I think one way will give
you a nice convex exterior and the other way will create all sorts
of nasty concavities. You can do some origami to see what I mean.
> The questions I have are
> a) do I also need a conditional line AC?
Yes.
> b) and if so, what are the associated control points? (at a guess B and D)
For diagonal AC, yes.
Don
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Message is in Reply To:
 | | Non-colanar quads question
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| I'm fixing the Perl code that generates the curved surface of the Half [1] Onion Dome (part 44511) from its control data. At the moment the surface comprises counter-clockwise wound quads (ABCD) [3] and conditional lines (AB, BC, CD and DA). (...) (20 years ago, 13-Jul-04, to lugnet.cad.dat.parts)
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