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 CAD / LDraw Files / Parts / 5341
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Subject: 
Non-colanar quads question
Newsgroups: 
lugnet.cad.dat.parts
Date: 
Tue, 13 Jul 2004 19:38:02 GMT
Viewed: 
2819 times
  
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).

The questions I have are
a) do I also need a conditional line AC?
b) and if so, what are the associated control points? (at a guess B and D)

thanks

William

[1] Or other fractional adjective of your choice [2]
[2] Footnotes especially for Larry ;-)
[3] It does now I've removed the bug that generated bow-tie quads
[4] And I got some weird looks on the train this morning as I was twisting and
folding used railway tickets to prove it to myself!



Message has 2 Replies:
  Re: Non-coplanar quads question
 
DOH! Who stole the P? (20 years ago, 13-Jul-04, to lugnet.cad.dat.parts)
  Re: Non-colanar quads question
 
(...) 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 (...) (20 years ago, 13-Jul-04, to lugnet.cad.dat.parts)

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