 | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Leonardo Zide
| | | | (...) When you draw a part with a pattern transparently, I guess it's not a good idea to remove the backfaces or you might not see the pattern from some angles. (...) About that discussion, IMO it would be better to have *everything* CCW instead of (...) (25 years ago, 30-Sep-99, to lugnet.cad.dev)
| | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Lars C. Hassing
| | | | | 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)
| | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Jacob Sparre Andersen
| | | | | | 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)
| | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —John VanZwieten
| | | | | | | | 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)
| | | | | | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Leonardo Zide
| | | | | | | | | (...) 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)
| | | | | | | | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Jeff Boen
| | | | | | | | | (...) 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)
| | | | | | | | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Leonardo Zide
| | | | | | | | | (...) Because the program doesn't work that way, it just turns backface culling on and draws everything in green, then switch to "frontface culling" (does it exist ?) and draws everything red. I've been busy finishing my first game project (not Lego (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Steve Bliss
| | | | | | | (...) That would be nice, but it's unrealistic. (...) No, they shouldn't. Just because the part XYZ is CW, a program can't assume that the primitive ABC is also CW. (...) I like this. I don't like it for use on primitives, but DOUBLE-SIDED could (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Jacob Sparre Andersen
| | | | | | | [ I got a bit too much good French red wine, so maybe I shouldn't try to answer now, but ... ] Steve: (...) Right. (...) Shouldn't all elements of transparent parts be drawn? (...) Yes. (I start to suspect that wine has a good influence on my (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Gary Williams
| | | | | | 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)
| | | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Steve Bliss
| | | | | (...) Why not simply: (...) Assuming the primitives are all defined so their faces are turned outward. I would see allowing both CW and CCW as a convenience for parts authors. There's no real difference between one way and the other. CW has a slight (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Jacob Sparre Andersen
| | | | | Steve: (...) Because our clever rendering programs will notice that the first transformation matrix has negative determinant, and therefore will swap the CW and CCW checks. Play well, Jacob ---...--- -- E-mail: sparre@cats.nbi.dk -- -- Web...: (...) (25 years ago, 1-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Steve Bliss
| | | | | (...) Jacob: (...) Why? Having a negative determinate *should* turn subfiles inside-out. IMO. That's a useful function. Having programs checking determinates is not useful, and wastes rendering time. Steve (25 years ago, 3-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Jacob Sparre Andersen
| | | | | Steve: (...) Hmm??? Yes you're right (again :-). Play well, Jacob ---...--- -- E-mail: sparre@cats.nbi.dk -- -- Web...: <URL:(URL) -- ---...--- (25 years ago, 3-Oct-99, to lugnet.cad.dev)
| | | | | | | | | | | | Re: CW/CCW, vertex sequence, co-planar, convex, (115kB) —Steve Bliss
| | | | | Jacob: (...) Steve: (...) Jacob: (...) It happens every once in awhile. Actually, which approach *would* be better? Examining the transformation matrix to determine the state of inversion, and adjusting the CW/CCW setting to correct for it, would (...) (25 years ago, 4-Oct-99, to lugnet.cad.dev)
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