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 CAD / MLCad / 2096
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Subject: 
Re: What about a LEGO TECHNIC tutorial
Newsgroups: 
lugnet.cad.mlcad
Date: 
Thu, 9 Jun 2005 12:42:05 GMT
Viewed: 
13035 times
  
In lugnet.cad.mlcad, Ross Crawford wrote:
In lugnet.cad.mlcad, Kevin L. Clague wrote:

  I'd love to be wrong about this, so if you know how to rotate part(s) about an
aribtrary axis in MLCad with simple button clicking, I'd like to be taught.

Not just a mouse, but Edit / Rotate / Keyboard Entry allows you to enter a full
rotation matrix (among other things). Of course you need to know what matrix
values to enter to get your desired result, but it's there in the GUI.

  What I'd like is to be able to click on an axle or pin, and have that define
the rotation axle (axis).  From there you would select other stuff that would
rotate one of the two possible direction.

Yes, that WOULD be nice, but it would also require axles[1] to have extra info
indicating where the axis is. This info is not currently available in LDraw
parts. You could hard-code it for axles[1], but that doesn't seem like a good
solution to me - you'd have to update the program every time someone requested a
new part. And that's not even looking at parts which can rotate around multiple
axes.

If you wanna go down this path, I'd much rather see a new LDraw "AXIS"
meta-command defined.

The new unpublished LSynth deals with this without any extra information.  I use
and LDraw file to desribe how to translate/rotate parts to the assumed default
position/orientation.

LSynth limits pulleys and gears to be planar.  It also assumes the first
synthesis constraint defines the plane of synthesis.  It cannot assume all
constraints have the same defined LDraw orientation with respect to LSynth's
synthesis plane.

This LDraw file that is external to the program, takes all constraints and
translates/orients them so that their axis of symmetry is the Z axis.  I thought
it was a clever solution to the problem you outlined above. It meets the need
without any new LDraw file format changes.  Also it is easy to change the LDraw
file with no changes to the original program.

Kevin


1 - and any other part you want to use this for, eg pins, turntables

Exactly! Turntables are the worst.  Their orientation is different than the
other "gears", and the gear plane is not on any of the X, Y, or Z planes.


ROSCO

Kevin



Message is in Reply To:
  Re: What about a LEGO TECHNIC tutorial
 
(...) Not just a mouse, but Edit / Rotate / Keyboard Entry allows you to enter a full rotation matrix (among other things). Of course you need to know what matrix values to enter to get your desired result, but it's there in the GUI. (...) Yes, that (...) (19 years ago, 8-Jun-05, to lugnet.cad.mlcad)

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