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Subject: 
Re: Voting Open for LCAD Parts Update 2000-01
Newsgroups: 
lugnet.cad.dev
Date: 
Wed, 12 Apr 2000 11:32:04 GMT
Viewed: 
1626 times
  
Steve Bliss <blisses@worldnet.att.net> writes:

True, but when bending the axle, the end parts (with the notches) also
bends, so one would need to chop this one up as well.  Of course, the
end parts are slightly thicker, and don't bend that much, which suggests
that your method might work, but they do bend significantly, IMO.

Good point.  I don't know if that level of detail is possible/practical
in LDraw.

I think I disagree with you.  I've found the Bezier curves to be a
good model for how the flexible axles bend in real life.  But it is
important to have a correct model for the flexible part in the first
place.  While the notched end parts are more rigid and bend less, the
thin conenctors at the ends bend even more, more or less evening out
the effect.  So a model where the axle bends evenly over the whole
length works quite good in my experience.  I've used a "mock up"
version of the flexible axles in this model:

    http://www.brickshelf.com/cgi-bin/gallery.cgi?f=192


But, it's always possible to inline the part, and modify the
code as much as desired.

Yes, but I'm not expecting people to do this manually.  Well not a
lot, anyway!  :-)

In my mock up, I divided the notched end parts of the flexible axles
into five parts, each with a 4 LDU length.  That worked quite well.  A
similar dividing of the official part would be great for my needs.

Of course, I can always continue using my mock ups.  But I feel that
for a part which is _meant_ to be bent, we should provide the users of
the LDraw library with means to model them as bent as well.  I can't
see many people using the bendable technic axles in a straight
fashion?


How about if I write a program that inlines a part, and shapes it to fit
along a specified spline curve?

A program?  Do you mean an MSDOS program?  Windows?  Perl?  I really
think that we should aim beyond software compatibility with the LDraw
parts library.  It should be an entity providing enough information
for it to be used on any kind of system, current and future, in my
opinion.  I realize that not all agree with me, though.

This is, BTW, why I wanted the information about the geometry of the
minifig parts to be shared.  I hear that a Windows program exists
which will compose a posed minifig according to some spicifications,
but I would still like to have the information needed to do this
manually (or automatically).  (So call me demanding!)  But noone
appears to have or to be willing to share this information, so the
minifig parts appear to be quite useless to me... :-(


That would be a really cool program to have. :)

Well, yes, it would!  :-)

Fredrik



Message has 3 Replies:
  Re: Voting Open for LCAD Parts Update 2000-01
 
(...) I haven't tried any of this but wouldn't Hermite curves work better ? Bezier curves don't need to go through the control points (except for the endpoints) and Hermite curves also have the advantage of letting you specify the tangent vector for (...) (24 years ago, 12-Apr-00, to lugnet.cad.dev)
  Re: Voting Open for LCAD Parts Update 2000-01
 
(...) Hmm. That sounds workable. (...) Portable Java would be best... (...) I agree, I just don't see how flexible parts can be coded in LDraw. If you've got some ideas in this direction, I'd love to see them. The lack of flex in LDraw parts is a (...) (24 years ago, 12-Apr-00, to lugnet.cad.dev)
  Re: Voting Open for LCAD Parts Update 2000-01
 
(...) [snip] Hey. why not add a new linetype or two to the ldraw format? this would solve both problems simultaneously: platform, and detail. (e.g. now it's the renderer's problem, not ours!) can't you just add: 6 c x y z a b c d e f g h i x' y' z' (...) (24 years ago, 13-Apr-00, to lugnet.cad.dev)

Message is in Reply To:
  Re: Voting Open for LCAD Parts Update 2000-01
 
(...) Yep. I'd change the rename of the 'Technic Connector Locking' to 'Technic Connector Toggle Locking'. (...) I know what you mean about the angled connectors. I suppose they should be "Technic Connector Angled". I'll think on that some more (...) (24 years ago, 11-Apr-00, to lugnet.cad.dev)

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