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Subject: 
Re: Modelling !
Newsgroups: 
lugnet.cad.dev
Date: 
Fri, 9 Jun 2000 19:59:19 GMT
Reply-To: 
rui.martins@/NoMoreSpam/link.pt
Viewed: 
768 times
  
On Fri, 9 Jun 2000, Steve Bliss wrote:

In lugnet.cad.dev, Rui Martins wrote:

Has some of you may remember, I have modelled the super car (8880) wheels and
tires, but when I modeled it I used Metric measurements (millimeters).

I would Like to know if there is an approved standard for a convertion ratio,
between millimeters and Ldraw units ?
So that I can scale the modelled parts and have them corrected!

I believe the conversion is 0.4mm = 1 LDU.  At least, that's what I always
use.

Thanks !

So, 1.00 mm = 2.5 LDU

I would also like to know when are we going to define orientation standards /
guidelines for when a part is created ?

Standards are already there.  They just aren't strictly enforced.  As I see
it, there are two basic "orientation rules":

1. Do the same thing as other, similar parts which were previously modeled.
2. If there is inconsistency in the existing parts library, go with the
majority or the senior parts.

I call this common sence, which I think everyone should use !

If a part truly breaks new ground, and there aren't any sufficiently
similar parts, then go with the following guidelines:

Are these your opinions only, or is assumed buy other people too ?
I agree with most of it !

1. If the part is symmetric along both horizontal dimensions, the wider
dimension should go along the X-axis.
Check!

2. If the part is asymmetric along one horizontal dimension, that dimension
should go along the Z-axis, with the front/tip of the part pointed toward
Z-.
Check!

3. Center the part on X-Z.

Shouldn't we always center on the center of a stud or connection (like wheels)?
Not on Total X/Z size.

4. Generally, put the top of part (not including studs) at Y=0.
Check!

5. Rotating parts *may* be centered on the point of rotation.
Check !

Maybe this should be placed in http://www.ldraw.org somewhere, maybe open anew
section for modellers, like a getting started page, with rules and guidelines.

Since I have seen technic Axels(non-threaded/threaded), wheels, Wind Screens,
Windows, doors, etc...  with non matching orientations.
(example: Two wheels which have different rotation axis)
suppose you had diferent orientations for different bricks, that would be a
mess, so Why did this happen for the parts I mentioned before ?

Because we're all volunteers.

I know that !

what I meant was:
How did those parts get by us, without this beeing noticed ?

P.S. I know it is a huge task if we ever need to make all these parts have the
same orientation. We would probably have to make a program to correct our dat
files, when the parts were reoriented. Sigh..

Interesting thought.  If the program was programmed with all the version
information of the parts (using the 0 Official L-CAD Update XXXXXXX line),
it could be done.

I meant something along the lines of a program that would rotate/translate all
parts (which would be defined in a .CFG file or something) according to a
specific transformation matrix for each, and applied this to one of our personal
model files, correcting the parts, their references/placement.

See ya

Rui Martins



Message has 1 Reply:
  Re: Modelling !
 
(...) Some of this has come up in various discussions. I'm not sure if all of it has or not. (...) No, centering on a stud isn't necessary. Look at 3001.dat, the 2x4 brick. It is centered on X-Z, not on a stud. The same applies for all other (...) (24 years ago, 9-Jun-00, to lugnet.cad.dev)

Message is in Reply To:
  Re: Modelling !
 
(...) I believe the conversion is 0.4mm = 1 LDU. At least, that's what I always use. (...) Standards are already there. They just aren't strictly enforced. As I see it, there are two basic "orientation rules": 1. Do the same thing as other, similar (...) (24 years ago, 9-Jun-00, to lugnet.cad.dev)

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