 | | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) I guess we could at least decide to use CCW to determine the normal of a face, unless there's someone who prefers to use CW ? Leonardo (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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(...) 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. (...) This can be done (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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Lars C. Hassing wrote in message <938787015.279086@ns.cci.dk>... (...) of (...) we will (...) Hold on. Why not just have a button in the CAD program to turn the part inside-out by automatically manipulating the orientation matrix in the parent dat (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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Steve Bliss wrote in message <37f4ab7d.64002272@l...et.com>... (...) Doh'! You're right. (...) I'm having a difficult time picturing in my mind how an asymmetrical part can have its orientation matrix in the parent dat file mirrored and rotated (to (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | 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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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) [DAT]
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Lars: (...) [...] (...) This would demand a lot of work before people could start using programs that use this fact. (...) Right. (...) Just check the determinant of the rotation matrix (but you know that I suppose). (...) I would rather use some (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) [DAT]
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Leonardo Zide wrote in message <37F383E1.CA6B8962@c...com.br>... (...) I agree with John Van in that we need three keywords: CCW, CW, UNKNOWN. As the rendering program is going to keep track of the number of mirrorings of the transformations (or (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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(...) It wouldn't matter if they were closed-volume or not--they could still be turned inside out accidently. And an inside-out closed-volume primitive wouldn't do anybody any good. (...) Why? Steve (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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(...) I'm willing to change my parts, if the standard changes. Assuming parts which are *not* C(C)W need to be flagged at all. (...) I agree completely. Steve (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | New Group Idea
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We should have a lugnet.cad.dat.clones group, now that someone over on RTL is doing megablocks parts. bThe group would be expressly for posting clone lego parts, official sets and MOC's. -- Jonathan Wilson wilsonj@xoommail.com (URL) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Michael Lachmann: (...) I think we agreed to use 0 CW and 0 CCW lines in the beginning of the files to indicate (C)CW compliancy, but you should have a look at what Steve actually has written in his parts. (...) It would be very nice if you (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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You mentioned that some parts have a "0 CW-Compliant" tag. Could we do something to make this a standard? Because than I could read this tag in MLCad and make the drawing faster!!!!! Tell me what you think! Mike (...) John VanZwieten wrote in (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB)
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(...) MAX2DAT isn't really meant to be a comprehensive part authoring tool... it's easy to build simple objects (like a 2x2 tile or 1x1 round plate) directly in LEdit with primatives... but objects like complex technic pieces, wheels, etc often have (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Gary Williams wrote in message ... (...) Okay, I made a bad assumption there, since a group of polygons may terminate flush against another polygon, without touching its edges. But still I think a performance improvement could be realized by using (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Jean-Pierre PARIS wrote in message <37F3B871.74AE196F@w...doo.fr>... (...) My algorithm doesn't require the vertices to exactly match; I was intending to pass one ray per polygon through the dat object, not an arbitrarily large number. And only if (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: *** PANEL 2409 ***
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(...) Ok, but I'm 95% sure that's where I grabbed the copy for ldraw.org originally.. :) Downloading now... -Tim Courtney ldraw.org Project Coordinator (URL) timcourtne ICQ: 23951114 (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: *** PANEL 2409 ***
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(...) I'm almost positive that the ldraw.exe at: (URL) include those updates, so Tim, please grab a copy. --Bram Bram Lambrecht / o o \ BramL@juno.com ---...---oooo-----(_...o---...--- WWW: (URL) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: Hidden surface removal, and vertex order in part/primitive DAT files
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Hello, Ok guys, I already announced that I coded such a tool in Java. At present, only one Ldrawer has asked for the code. In fact, it's an alpha release. Thus, I should find beta testers first. Anyway it has already translated some pieces! Here is (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | Re: To Tore Eriksson
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(...) They could also be differentiated simply by appending Type 1 and Type 2 to the name. Steve (25 years ago, 30-Sep-99, to lugnet.cad.dev)
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| | 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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