 | | Checking for bowtie quads? —Fredrik Glöckner
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| | | Do anybody know of a simple algorithm for checking if a quad is of the "bowtype" kind? I.e. a quad where two of the edges cross each other. I understand that Lars C Hassing's L3P does this check, so perhaps he can help me? Thanks in advance! Fredrik (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | Re: Checking for bowtie quads? —Don Heyse
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| | | | (...) Lar's L3Input.cpp is in the latest ldglite source (which is available at the usual place). It contains the bowtie checking code and is quite nice. Don (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | | Re: Checking for bowtie quads? —Fredrik Glöckner
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| | | | (...) Thanks, I've got it! I didn't know the check was that involved, though... Fredrik (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | | Re: Checking for bowtie quads? —Don Heyse
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| | | | (...) Yeah, I tried to think of a simpler way to do it myself. But all my ideas required converting the quad from 3D coords to 2D coords first so my feeble brain could handle it. :^) Don (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | | Re: Checking for bowtie quads? —Damien Duquennoy
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| | | | | Just a question... Does the quad should be plane, is there any problem to get 4 non-coplanar points ? Damien. (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | | | Re: Checking for bowtie quads? —Leonardo Zide
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| | | | | | (...) Quads should be plane and follow a correct order, the points must be in a correct order. Search the old messages and you'll find several discussions about it. Leonardo (25 years ago, 29-Mar-00, to lugnet.cad.dev)
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| | | | | | Re: Checking for bowtie quads? —Don Heyse
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| | | | (...) Wow, I'm glad I revisited this since I think I can save some rendering time by saving the vertex normals from the bowtie checks for the OpenGl lighting phase in LdGLite. Here is the algorithm I came up with before I decided to use the L3 code (...) (25 years ago, 30-Mar-00, to lugnet.cad.dev)
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| | | | | | Re: Checking for bowtie quads? —Rui Manuel Silva Martins
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| | | | It's funny but two weeks ago, I developed exactly this method, the one with the cross products, and all the findings you got, too. (...) Isn't 3D math a wonderfull thing P.S. Maybe if I would have look at someone elses code or book, my life could (...) (25 years ago, 30-Mar-00, to lugnet.cad.dev)
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