Parts Primitives : 357


CAD / LDraw Files / Parts / Primitives / 357	356 \| 358

Subject:	Re: Stud5 and type 5 lines at edge of cylinders.
Newsgroups:	lugnet.cad.dat.parts.primitives
Date:	Thu, 2 Oct 2003 04:09:45 GMT
Viewed:	3723 times

In lugnet.cad.dat.parts.primitives, Travis Cobbs wrote:

In lugnet.cad.dat.parts.primitives, Paul Easter wrote:

... “mess” ... deleted :-)

Ok... I’m a bit lost is all this mess. I need to know where we stand on this issue. I have a Primitive Generator program written with Visual Basic available for people to download and use. If I have handled this incorrecly, I need to know so I can try to fix the program.

I brought this up again, since I was reviewing my previous votes on the Parts Tracker; http://www.ldraw.org/cgi-bin/ptdetail.cgi?f=p/1-16cyli.dat

Paul

If you would like to try out the Primitive Generator, it can be downloaded from this page; http://www.geocities.com/pneaster/prim-gen.htm

I believe the consensus was that the line between the last edge and the control point hanging out in space should be tangent to the cylinder, that this will help cases where the cylinder meets a box at right angles, and that it will help (but not fix) the S-curve problem.

So, on a quarter cylinder, the line (which of course wouldn’t be drawn) between the edge of the cylinder and the control point in space is represented by the red lines in this diagram:

With the above style type 5 lines, you have to have a type 5 line at both ends, or it won’t work right (hence the two red lines). I’m not sure if I’m describing this well.

I’m not sure we got a consensus about doing things like the above, but on the other hand, I don’t think anyone objected.

--Travis Cobbs

That’s what I was afraid of... That is not how I handled it in the program. So, now this should apply for any segment files, right? 1-16,1-8,3-16,1-4,7-48, etc? If so, I will have to rethink how to calculate those points.

now... this brings us to the next area.... this also applies to cones, right? IIRC, I use the same procedure for conditional lines for both cylinders and cones, with minor changes.

Paul.

Message has 1 Reply:

		Re: Stud5 and type 5 lines at edge of cylinders.
(...) I think ideally this would be used on all segmented primitives that are circular and not flat (obviously it doesn't apply to primitives like disks and rings). So think that the same logic would apply to cones. Incidentally, I think the 1/8 (...) (21 years ago, 3-Oct-03, to lugnet.cad.dat.parts.primitives, FTX)

Message is in Reply To:

		Re: Stud5 and type 5 lines at edge of cylinders.
In lugnet.cad.dat.parts...rimitives, Paul Easter wrote: ... "mess" ... deleted :-) (...) have handled this incorrecly, I need to know so I can try to fix the (...) this page; (...) point hanging out in space should be tangent to the cylinder, that (...) (21 years ago, 2-Oct-03, to lugnet.cad.dat.parts.primitives, FTX)

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