 | | Rect primitive with one edge missing?
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Is there a primitive for a rectangle with one edge missing? I can't seem to find one, and I think it would be useful. It certainly would for a part that I am currently working on -- reducing three lines of code to one, 48 times. If there isn't one, (...) (22 years ago, 26-Jan-03, to lugnet.cad.dat.parts.primitives, lugnet.cad.dev)
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| | Re: Wierd shading in LDView
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(...) The 1-4con0 primitive should arguably have a different name, because it is a different shape than all the other cone primitives. Specifically, it comes to a point, while all the other cone primitives are missing the point (they're open at both (...) (22 years ago, 24-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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<snip> (...) Yes. lsynth only deals with 1 peice of stretched rubber band at a time, which is why I was keeping those other three pulleys a secret from Don. Kevin (...) (22 years ago, 24-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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"Kevin Clague" <kevin_clague@yahoo.com> skrev i meddelandet news:H94xC1.11z@lugnet.com... (...) calculate (...) If the condition above (Dist(...) etc.) holds, then it's just a matter of projecting the circle centers onto the line, ie. solve for a (...) (22 years ago, 23-Jan-03, to lugnet.cad.dev)
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| | Wierd shading in LDView
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I was updating part 3847 to use the 1-4con0 primitve and I notice some wierd shading at the tip. I then open the 1-4con0 primitive directly and there were no shading problems I could see. Download 3847 at the Parts Tracker to see what I mean. (URL) (...) (22 years ago, 24-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) What you really need is to find a way to find just one side of the "rubber band". Say, pulley A to pulley B, "Side one". Then you could use the same function to determine pulley B to C, side one or two, and so on... Right? Paul (22 years ago, 24-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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Kevin, I have been watching this thread with great interest and it is really fun to watch the community pitch in and assist you. Would you do me a favor. When you finally have the solution, could you summarize in a post? I plan on using this as a (...) (22 years ago, 23-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) I couldn't find it anywhere in this thread, so the project page is here: (URL) on the Browse CVS link near the bottom to view the source code. The homepage is here: (URL) just to test things out a bit, I logged into the sourceforge compile (...) (22 years ago, 23-Jan-03, to lugnet.cad.dev, lugnet.cad.dev.mac)
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| | Re: Tangent between two circles in 3D space?
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(...) This looks great! This is what I was trying say the other day during my ah,hah! moment, but not so tersely. Now I just need to know how to calculate the intersection of the line and each circle and I'll be all set I think. I'll do some (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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"Kevin Clague" <kevin_clague@yahoo.com> skrev i meddelandet news:H92o0p.CGB@lugnet.com... (...) a (...) Line = Intersect(C1.Plane, C2.Plane) if (Dist(C1.Center, Line) = C1.Radius) and (Dist(C2.Center, Line) = C2.Radius) ... (Or have I (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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Agreed! -- Steven B. Combs, Publisher Bricks in my Pocket (BimP) (URL) Submission Information: (URL) member #414 "Kevin Clague" <kevin_clague@yahoo.com> wrote in message news:H92o80.D83@lugnet.com... (...) question! (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) More or less... there are 4 tangents to the 2 cylinders that happen to be on the circles. (...) Some thoughts that could perhaps (with [lots of] work) lead to an iterative solution: - Select one of the circles, then choose one radius of this (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) Yes. This *is* the ultimate (and probably universal) solution, although we probably need to be able to find one of four cylinders between any two circles in 3D space. You are thinking in terms of pulleys always on the outside of the band. With (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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Hi Kevin, I think common tangent to circles is too restrictive, since rubber belts tolerate quite a lot of misalignment. ((URL) the problem should be reformulated as: Two circles in 3D space define two cylinders orthogonnally extruded from them. (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Seam width
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(...) Please see (URL) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Seam width
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(...) In LDView, I do a few things. First, I check to see if the file I just loaded is a part. In order to be a part, it has to satisfy two criteria. First, it can't be the child of a part. Second, it has to either be in the LDraw Parts directory, (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: LDraw Infotip Shell Extension DLL
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(...) parts directories, researching parts stuff... :) (...) This version is very nice, just as it is. :) But if you were to figure out to make LDraw files display rendered images in Explorer's "thumbnail" view, that would be awesome... Steve (22 years ago, 22-Jan-03, to lugnet.cad, lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) Well, I'll start 8?) Step 6 - thats radius Step 7 - should be sin T = L / R ROSCO (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) OK. Here's my rather convoluted analysis: 1. Find the plane of pulley A 2. Find the plane of pulley B 3. If they dont intersect, no tangent so stop here 4. Find the angle between them, call it T 5. Find the normal to plane A that passes (...) (22 years ago, 22-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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I have a child in fourth grade, and like many his age, he is a natural born lawyer looking for loopholes, so 'm well versed in the tactic because it is hard to resist.... If you notice my original post, I didn't even mention pulleys, I just asked (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) Ah Ha! Apparently there were TWO other pulleys you weren't telling us about. (URL) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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Agreed! -- Steven B. Combs, Publisher Bricks in my Pocket (BimP) (URL) Submission Information: (URL) member #414 "Kevin Clague" <kevin_clague@yahoo.com> wrote in message news:H92o80.D83@lugnet.com... (...) question! (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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Don, I'm assuming four pulleys in this case. Two are parallel to each other where the rubber band bends to be non-planar, and two others that pull the band around the two parallel pulleys. Kevin (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) Don, this is what I do for planar rubber bands and it works great if the two pulleys are in the same plane. But I can imagine a four pulley configuration where the first pulley is parallel to the YZ plane, the second pulley is parallel to the (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) It sounds like you want the intersection point of the 2nd circle with the plane of the first circle. I guess that should be exactly one point unless they're in the same plane. However, I don't see how the rubber band gets back to the first (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) I'm sure you're probably looking for a solution with x,y,z coords, but just in case, the 2D solution is on page 7 of Graphics Gems, and also here: (URL) think you should be able to transform your circles into the x,y plane with one center at (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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Steven, I debated with myself about adding L3PAO, because it certainly has had a positive effect for people who don't like command lines (and even for some of those that do). LPub has all the capabilities of L3PAO plus a *lot* more, so I felt like (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) With two circles in the same plane you can have four possible tangent lines. LSynthcp uses this to calculate straight line segments of rubber bands around pulleys. In 3D space you can have circles that are tangent along one line. Imagine a (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) What have you tried so far? And which tangent? Think about it, there's an infinite number of solutions. Even on a plane there are multiple solutions. Recommendation: start with the book _Computational Geometry in C_ by Joseph O'Rourke. -Erik (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: Tangent between two circles in 3D space?
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(...) Wouldn't they have to be on the same plane in order to find the tangency? Or did you mean the tangency of two spheres? Steven (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) I just completed Chapter 9 of your book and I think I answered my own question! Steven (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Tangent between two circles in 3D space?
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Anyone know how to find out the tangent between two cicles in 3D space? Kevin (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) ;^) Relax, we are talking about both on the command line that starts the program, as well as on the LDraw meta-commands that start synthesis of a specific part. Notice he said getopt() style parameters, not getopt() to get the parameters. (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) Whoah, wait a minute! I like getopt() as much as anyone, but I thought we were talking about something to go *inside* the file on the SYNTH BEGIN line(s), not necessarily on the command line. Units may be universal for all synthesized parts in (...) (22 years ago, 21-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) Much better! I've been programming on Windows too much lately (isn't any amount too much? ;^) Kevin (...) (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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| | Seam width
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Hi. Just wondering: How do you calculate the seam width in programs like L3P and LDView? Do you just scale the part by x% ? Or ? Trond Hasse Lie Norway (o\_/o) (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) What about getopt() style parameters, eg: -f foo.dat -l 20 -u cm --filename foo.dat --length 20 --units cm ROSCO (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) Yeah, I thought so. Other options are copying the line before the strupper(), or using strnicmp() or strncasecmp() for the keyword test. The copy method is easier to do in a portable way. (...) I like the named parameters. That makes it easy (...) (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) I'd like to discuss changes before they are made, so I can keep track of new capabilities of the program. (...) Yes. I was trying to make lsynth not case sensitive when it came to recognizing keywords, but I don't like the fact that it changes (...) (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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| | Re: lsynthcp community development project setup on sourceforge
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(...) I don't know about the math, but I do have a few thoughts after a quick peek at the sources. So how should we go about making changes? Discuss them here first, or just put them in CVS with an appropriate comment if we think they won't break (...) (22 years ago, 20-Jan-03, to lugnet.cad.dev)
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