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some thoughts about train track part origin choices
avatarDecember 04, 2013 01:03AM
At part
http://www.ldraw.org/cgi-bin/ptdetail.cgi?f=parts/85977.dat
some questions arose about where to put the origin of train track parts.

The X and Z choice usually is not a problem, both for curved or straight parts:
we there can simply follow the principles of our usual practice, i.e. "part center".
This is also what existing parts do, e.g. 3229a.dat, 3229ac01.dat, 3229ac04.dat.

Regarding the Y origin, there is the question
"Should the origin be (A) at the top of the studded sleepers or (B) at the top of the rails?"
The current status in the library needs to be explained historically:
The rail parts e.g. 3229a.dat existed in the library long time already.
As usual for parts, they had their origin at the top.
This origin was kept when 3229ac01.dat was created, an assembly of two curved rails.
This origin was kept when 3228ac02.dat was created, an assembly of two straight rails.
This origin was kept when 3228bc02.dat was created, an assembly of two straight rails plus sleeper.
This origin was kept when 948ac02.dat was created, a point.
This is the 4.5V blue and grey rails story.
The same origin was applied to the analogous 12V blue and grey rails, e.g. 73696c04.dat.

So to make a long story short: carrying over the origin choice of the single rail part to the rails assemblies
led to the effect that the vertical origin of all 4.5V and 12V train track parts and assemblies is at the top of the rails.

The origin question now again arises for the 9V train track.
http://www.ldraw.org/cgi-bin/ptreviewsummary.cgi?f=traintrack9v
(with or without metal top), and for other train tracks where the rails are firmly attached to the sleepers.
There the question is if the vertical origin should be
(A) at the top of the sleepers or
(B) at the top of the rails.
Both solutions have advantages and disadvantages:
Solution (A) would make the new train track parts better match plates.
Solution (A) would be the intuitive one if one did not know about existing train track parts.
Solution (B) would make the new train track parts better match existing train track parts.
Both solutions are no problem for train track layout software like BlueBrick.

So what to do now? Current situation:
- Official train track parts out in the wild have "origin at rail top".
- *SOME* of newer train track parts with "origin at sleeper top" already "sneaked" out, e.g. 32087.dat
- all newer train track parts currently on the PT like 74746.dat or 53401.dat or 85976.dat follow the "origin at sleeper top" strategy

I have no real strong opinion here. We could opt for one of these solutions:
(i) make all train track parts have origin at rail top
(ii) make all train track parts have origin at sleeper top
(iii) let some have it this way, others the other way

Solution (i) would require to re-position official file 32087.dat.
Solution (ii) would require to re-position many official 4.5V and 12V files
Solution (iii) would create inconsistency but would minimize current trouble

After having written this, I slightly tend to solution (iii)...

Edited 2 time(s). Last edit at 2013-12-04 01:11AM by Steffen.
SubjectAuthorViewsPosted
some thoughts about train track part origin choices Steffen228December 04, 2013 01:03AM
Re: some thoughts about train track part origin choices Philippe Hurbain109December 04, 2013 01:32AM
Re: some thoughts about train track part origin choices Michael Heidemann110December 04, 2013 08:56AM
Re: some thoughts about train track part origin choices Steffen99December 04, 2013 09:11AM
Re: some thoughts about train track part origin choices Ronald Vallenduuk107December 05, 2013 03:24PM
Re: some thoughts about train track part origin choices Steffen118December 05, 2013 03:27PM



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