Special:
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[DAT] (requires LDraw-compatible viewer)
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Subject:
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LDraw FAQ
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Newsgroups:
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lugnet.cad, lugnet.cad.dev
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Date:
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Tue, 9 Feb 1999 11:04:09 GMT
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Viewed:
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720 times
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LDraw FAQ
0) About this FAQ
The questions and answers in this FAQ is mainly summaries of
communication in the discussion group lugnet.cad.dev.
0a) Table of contents
* 0) About this FAQ:
+ a) Table of contents
+ b) Locations of the FAQ
+ c) Useful addresses
* 1) What is this LDraw thing?
* 2) Where can I get a copy of LDraw?
* 3) Can I get the source code?
* 4) What platforms does the program work on?
* 5) Where can I find examples?
* 6) Who made it?
* 7) What does LEGO (the company) think of it?
* 8) Where can I ask questions about LDraw?
* 9) Mailing list?!? What mailing list?
* 10) Other LEGO CAD programs
* 11) How can I convert a LDraw .dat file to a .bmp file?
* 12) Can I use models as if they were pieces?
* 13) How can I insert comments in the .dat files?
* 14) How can I get the pieces to line up?
* 15) How can I turn a hinge from one step in the instructions to
the next?
* 16) What's the most recent edition of the LDraw package?
* 17) What does the numbers that follow the "-a" parameter mean?
* 18) Why don't the -MS and -MP options draw the last step of my
model?
* 19) What do I do when LEdit crashes?
+ a) - when you try to get the on-screen parts list
+ b) - with the message "Graphics error: Invalid device driver
file (EGAVGA.BGI)"
* 20) What is the .DAT file format?
* 21) How can I make ray-traced images of LDraw models?
* 22) How does one map a bitmap onto a LDraw object?
* 23) How can I get a clear brick in LDraw?
* 24) How can I create a part that is not yet in LDraw?
* 25) How can I find the numbers for a view in LDraw?
* 26) Where does LDraw look for files
* 27) What is the colour code for ... ?
* 28) Runtime Error 200 ???
* 29) Runtime Error 003 ???
* 30) Can I get LDraw to put the BMP files somewhere else?
* 31) What is the parts voting procedure?
0b) Locations of the FAQ
The LDraw FAQ will be posted to the discussion groups rec.toys.lego,
lugnet.cad, and lugnet.cad.dev.
The FAQ can be downloaded/read at these URL's:
* <URL:http://hugin.risoe.dk/JJ_Memorial/FAQ/> (hypertext)
* <URL:http://hugin.risoe.dk/JJ_Memorial/FAQ/text> (plain text)
0c) Useful addresses
FAQ editor:
Jacob Sparre Andersen (sparre@cats.nbi.dk)
Expert:
James Jessiman (July 25th, 1997, James passed away)
1) What is this LDraw thing?
LDraw is a DOS program that allows you to draw LEGO models, create
building instructions for them, etc. - A LEGO-style Computer Aided
Design system.
The current edition can generate a sequence of .bmp files (MS-Windows
bitmaps), one for each step in a building instruction, from a LDraw
.dat file.
You can edit LDraw files with the accompanying LEdit program or with
your favourite text editor (the latter is said to be very hard, but I
do it anyway. - Jacob).
It's free!
2) Where can I get a copy of LDraw?
You can download LDraw directly from James' Web site at
<URL:http://silo.riv.csu.edu.au/%7Ejjessiman/ldraw/index.html>, but I
suggest that you go through the James Jessiman Memorial
(<URL:http://hugin.risoe.dk/JJ_Memorial/official.html>) where you can
get new collections of parts as well. You can also download LDraw from
Bram Lambrecht's LDraw and LEdit tutorial.
3) Can I get the source code?
No!
But you can get the source code for LDLite (a Win32 replacement) at
<URL:http://www.gyugyi.com/l3g0/ldlite/>.
4) What platforms does the program work on?
MS-DOS. Including DOS in OS/2, Win-95 and Win-NT.
There's no Mac and Unix versions.
But there is one in progress (see section 3).
5) Where can I find examples?
These documents contains LDraw'n models. Either as data files for
LDraw or as processed images:
L3P Gallery (includes ray-traces):
<URL:http://www.netby.net/Nord/Mandelvej/Hassing/l3pgal.html>
Jacob's LEGO building instructions:
<URL:http://hugin.risoe.dk/LEGO/Byggevejledninger/>
Space ship Black 'n' White:
<URL:http://silo.riv.csu.edu.au/%7Ejjessiman/lego/models/jsa/BL
KWHT.HTML>
Train car and office building:
<URL:http://tortie.me.uiuc.edu/%7Edorneich/lego/Elego.html>
Mechanical joystick and the Blacksplorien shuttle:
<URL:http://www.uni-karlsruhe.de/Uni/RZ/Personen/rz71/Private/L
ego/lego.html>
Various models:
<URL:http://www.chuh.org/Students/Bram-Lambrecht/LEGO/Models.ht
ml>
RC Car and 4x4 with differentials:
<URL:http://www.nd.edu/%7Elego/grp2/www/4x4instr.htm>
Jaco van der Molen's USS Enterprise:
<URL:http://www.globalxs.nl/home/j/jmolen/stinlego/stinlego.htm
>
6) Who made it?
James Jessiman. James passed away July 25th, 1997.
We are trying to continue James' work in the discussion group
lugnet.cad.dev (see section 9). Many people are working on modelling
more parts, and Paul Guygyi has written a LDraw clone for MS-Windows.
7) What does LEGO (the company) think of it?
No idea!
8) Where can I ask questions about LDraw?
If you can't find the answer here, please ask on the discussion groups
lugnet.cad or lugnet.cad.dev, and write a section for the FAQ based on
the response.
9) Mailing list?!? What mailing list?
Until recently technical discussions regarding LDraw (and other LEGO
related CAD packages) were located on the "LEGO-style Computer Aided
Design" mailing list. This mailing list has been superceded by the
discussion group lugnet.cad.dev. You can access the discussion group
in three ways:
* Through the web page
<URL:http://www.lugnet.com/news/display.cgi?lugnet.cad.dev>
* Through e-mail (see the guidelines at
<URL:http://www.lugnet.com/news/mail/>)
* As newsgroups (see the guidelines at
<URL:http://www.lugnet.com/news/>)
10) Other LEGO CAD programs
Gryphon Bricks (see <URL:http://www.gryphonsw.com/bricks/index.html>)
For making building instructions.
Paul Gyugyi's L3G0 (see
<URL:http://www.gyugyi.com/legocad/legocad.html>)
For ray-tracing.
SimLego (see <URL:http://home2.swipnet.se/%7Ew-20413/simlego.htm>)
For making building instructions.
Development stopped 1997.06.23. The author, Tore Eriksson, said
that "SimLego will never come close to LDraw".
Visio
Huw Millington has a parts library for this.
LeoCAD (see <URL:http://www.geocities.com/Colosseum/3479/leocad.htm>)
LeoCAD is a LEGO CAD program for Windows (95 and NT). It can
import and export LDraw files.
Anton Raves' LEGO library for POV-Ray (see
<URL:http://ourworld.compuserve.com/homepages/Anton_Raves/How_T
o.html>)
POV-Ray is a free ray-tracing program.
Paulo Caparica Junior's LDraw to DXF Converter (see
<URL:http://www.geocities.com/Eureka/Gold/3269/>)
ld2vr (see <URL:http://perso.wanadoo.fr/paris.jean-pierre/LD2VR/>)
A LDraw to VRML compiler.
Matthew D. Bates' Track Designer (see
<URL:http://ourworld.compuserve.com/homepages/train_depot/td.ht
m>)
A track lay-out program for MS-Win.
11) How can I convert a LDraw .dat file to a .bmp file?
If you want to convert the LDraw .dat file MY_MODEL.DAT to a sequence
of .bmp files;
1. Go to the catalog where the LDRAW.EXE file resides.
2. Execute the command LDraw -MS MY_MODEL.DAT at the DOS command
line.
You will find a sequence of .bmp files named MY_MOD01.BMP,
MY_MOD02.BMP ... in the subdirectory BITMAP.
12) Can I use models as if they were pieces?
Yes. The .dat files just have to be stored in the MODELS subdirectory.
You refer to them by the file name (no path specification), just as
with the pieces (whose .dat files are found in the PARTS
subdirectory).
13) How can I insert comments in the .dat files?
In LEdit:
1. Insert a new piece.
2. Pick /Edit Line-Type Comment
3. Type in your comment.
4. The piece line will change to a comment line.
In a text editor: Start the line with a zero.
14) How can I get the pieces to line up?
I'll list various peoples suggestions.
Jacob
Jeremy H. Sproat suggests:
I start with the 3-D view, then go to two of the "normal" views to
line the puppy up. If I'm putting a piece in among a bunch of others
and my view is obstructed, it helps to turn on the "Stop at cursor"
option.
If I'm putting in a piece that needs to go at an odd angle, and there
is already another piece at the same angle, I load the .dat file into
a text editor and copy and paste the line of the first piece. I then
load it into LEdit and move it around.
Sproat
Bram Lambrecht suggests:
I check a couple of different views to check sometimes. I usually use
James' method: hit down, so that all but the studs are visible. If the
fit is correct, bring the piece up the correct number of moves.
Bram Lambrecht
15) How can I turn a hinge from one step in the instructions to the next?
1. Draw the model up to the step before where the piece changes.
2. Add the step commands to the .dat file, including the last one.
3. Add a '0 CLEAR' command at the end of the file.
4. Copy everything before the last step command to after the clear
command, so that you have the model repeated.
5. Remove the step commands from the latter half of the file.
6. Change the orientation of the hinge in the latter half of the
file.
If you use LEdit, you will have to exit it, to do step 3 to 4/5 in a
text editor.
16) What's the most recent edition of the LDraw package?
You can find links to the package itself, and to the L-CAD parts
collections at <URL:http://hugin.risoe.dk/JJ_Memorial/official.html>.
The last collection of new parts is from January 1999.
There is a tutorial for LDraw and LEdit at
<URL:http://library.advanced.org/20551/>.
External units:
Tore Eriksson's LDraw Launcher (see
<URL:http://home2.swipnet.se/%7Ew-20413/ldlaunch.htm>)
Patrick Sayre-Little's printable visual parts catalog (see
<URL:http://www.calpoly.edu/%7Ewsayreli/lego.html>)
For MS Word 95/7.0
Jacob Sparre Andersen's Fractal landscape generator for DOS, OS/2, and
AIX (see
<URL:http://hugin.risoe.dk/meyer/LEGO/V%E6rkt%F8j/#landskaber>)
:
May 9th 1997.
Steve Bliss' LDraw Add-On for Win-95 and Win-NT (see
<URL:http://home.att.net/%7Eblisses/ldaddon.html>):
May(?) 1998.
Jacob Sparre Andersen's file splitter for DOS, OS/2, and AIX (see
<URL:http://hugin.risoe.dk/meyer/LEGO/V%E6rkt%F8j/#Split.LDraw.
Files>):
June 20th 1997.
Huw Millington's parts list generator for Win-95 (see
<URL:http://www.pncl.co.uk/%7Ehuw/lego/ldraw/ldrawlist/ldrawlis
t.html>):
June 27th 1997.
Richard Goldfinder's program that creates Bezier curves for LDraw (see
<URL:http://www.eskimo.com/%7Egoldfndr/lego/>):
June 14th 1997.
Tore Eriksson's bitmap to LDraw converter (see
<URL:http://home2.swipnet.se/%7Ew-20413/bmp2dat.htm>):
June 14th 1997
Lutz Uhlmann's LDraw to POV-Ray converter (see
<URL:http://titan.informatik.uni-bonn.de/%7Euhlmann/files.html>
):
January 5th 1999
Lars C. Hassing's LDraw to POV-Ray converter (see
<URL:http://www.netby.net/Nord/Mandelvej/Hassing/l3p.html>):
January 3rd 1999
Tore Eriksson's LDraw vector drawing program (see
<URL:http://home2.swipnet.se/%7Ew-20413/ldd.htm>)
July 15th 1997.
You should always remember to have a look at the overview of LDraw
resources at the James Jessiman Memorial (see
<URL:http://hugin.risoe.dk/JJ_Memorial/ldraw.html>).
17) What does the numbers that follow the "-a" parameter mean?
The first three numbers determine the position along the screen X
axis. The first one is how much the model X axis affects the position.
The next one is how much the model Y axis affects the position and the
last one is how much the model Z axis affects the position.
So:
Screen X = Model X * First number +
Model Y * Second number +
Model Z * Third number
The next three numbers are for the screen Y axis and finally the last
three are for the screen Z axis. I.e.:
Screen Y = Model X * Fourth number +
Model Y * Fifth number +
Model Z * Sixth number
Screen Z = Model X * Seventh number +
Model Y * Eighth number +
Model Z * Ninth number
The screen Z axis is not really drawn. It is only used to determine
which piece is visible and which piece isn't.
The screen X axis goes to the right, the Y axis goes down, and the Z
axis goes away from you (into the screen).
18) Why don't the -MS and -MP options draw the last step of my model?
You have to insert a step command at the end of the .DAT file. [This
problem should have been solved in the present version of
LDraw/LEdit.]
19) What do I do when LEdit crashes?
Stop editing your .DAT files in Notepad! Or at least, stop making
mistakes when you do edit them. [Says Steve]
19a) - when you try to get the on-screen parts list
Run MAKELIST to regenerate the file PARTS.LST. [This problem should
have been solved in the present version of LDraw/LEdit.]
19b) - with the message "Graphics error: Invalid device driver file
(EGAVGA.BGI)"
There are two possible reasons for this. Either
1. you have copied another version of the file "EGAVGA.BGI" on top of
the one delivered in the LDraw package,
or
2. you run LEdit in/from a catalog where you keep another version of
"EGAVGA.BGI" than the one delivered in the LDraw package.
In the first case, you will have to reinstall all of LDraw (run the
installation programs with the option -y to speed up the process). In
the latter case, you should try to run LEdit from the catalog LDraw
and LEdit are installed in.
20) What is the .DAT file format?
.DAT files are text (yes, you can edit them in EDIT or Notepad or your
favourite text editor). Each line is a single command, and each line
is independent. The commands are (mostly) very simple, there are only
a few different commands. Specific commands are identified by the
first number on the line, which is called the line-type. The contents
and format of the rest of the line depend on the line-type. I do not
know of any length-limit on command lines.
Line types
Each line in the .DAT file is a single command. The first number on
each line is the line type, valid values are 0 through 5, with the
following meanings:
0:
comment or meta-command
1:
Part-file reference
2:
Line
3:
Triangle
4:
Quadrilateral
5:
Draw a line between the last two points, if both points are on
the same side of the line between the first two points.
If the line type for a line is not a valid value, the line is ignored.
Meta-commands require a keyword to follow the line-type. These
keywords must be in all-caps, and you should assume that if the
meta-command doesn't require more information, you shouldn't give it
any additional information.
Commands
Here is a complete (as far as I know) list of LDraw drawing- and
meta-commands:
* Model Title
* Step
* Write
* Clear
* Pause
* Save
* Comment
* Part
* Line
* Triangle
* Quadrilateral
* Optional-Line
And here are the details of each command. Meta-commands are listed
first, with the "real" commands after. The command-names are wholly
made up by me, I don't have any "official" names for these things.
Model Title.
The descriptive name of the model- or part-file.
Line format:
0 title-text
where title-text is whatever you want to name your model.
This is a meta-command, sort of. If the first line in a .DAT
file has line-type 0, the remainder of that line will be
considered the title for the file (at least for parts files).
This overrides any meta-commands on the line.
Step meta-command.
Marks the end of a building step.
Line format:
0 STEP
This command will cause LDraw to stop until you press <enter>,
and it will cause LDraw to save the current image into a bitmap
file in the ldraw\bitmap directory. These two effects are
controlled by the -M command line option (see ldraw.doc for
info on -M).
Write meta-command.
Displays a message at the top of the screen.
Line format:
0 WRITE message-text
or:
0 PRINT message-text
where message-text is whatever you want displayed on the
screen.
The displayed message is not saved in the image-bitmap files.
Clear meta-command.
Clears the screen.
Line format:
0 CLEAR
Useful for advanced model files. Don't forget to redraw all the
parts you just erased by using this command.
Pause meta-command.
Causes LDraw to stop until you press <enter>.
Line format:
0 PAUSE
This is like the Step command, but it does not save bitmaps,
and it is not affected by the -M command line option.
Save meta-command.
Causes LDraw to save the current image in a bitmap.
Line format:
0 SAVE
This is also like the Step command, but it does not cause LDraw
to pause, and it is not affected by the -M command line option.
Part command.
Inserts a part defined in another .DAT file.
Line format:
1 colour x y z a b c d e f g h i part.dat
where
+ colour is a colour code: 0-15, 16, 24, 32-47, 256-511
+ x, y, z is the position of the part
+ a - i are orientation & scaling parameters (see below for
more on this)
+ part.dat is the filename of the included file
Parts may located in the p\, parts\, or models\ subdirectories
(under the ldraw\ directory). They may also be located in the
current directory. James has arranged the directories so that
p\ contains elements that are intended to be used as part of
elements (such as stud.dat). The parts\ directory contains
finished parts, ready to be used in construction models. And
the models\ directory contains construction models.
Part files can also include Part commands. There don't seem to
be a specific limit to how deep these references can go.
Line command.
Draws a line between two points.
Line format:
2 colour x1 y1 z1 x2 y2 z2
where
+ colour is a colour code: 0-15, 16, 24, 32-47, 256-511
+ x1, y1, z1 is the position of the first point
+ x2, y2, z2 is the position of the second point
Triangle command.
Draws a filled triangle between three points.
Line format:
3 colour x1 y1 z1 x2 y2 z2 x3 y3 z3
where
+ colour is a colour code: 0-15, 16, 24, 32-47, 256-511
+ x1, y1, z1 is the position of the first point
+ x2, y2, z2 is the position of the second point
+ x3, y3, z3 is the position of the third point
Quadrilateral command.
Draws a four-sided, filled shape between four points.
Line format:
4 colour x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4
where
+ colour is a colour code: 0-15, 16, 24, 32-47, 256-511
+ x1, y1, z1 is the position of the first point
+ x2, y2, z2 is the position of the second point
+ x3, y3, z3 is the position of the third point
+ x4, y4, z4 is the position of the fourth point
Optional-Line command.
Draws a line between the first two points, if the projections
of both points onto the screen are on the same side of an
imaginary line between the projections of the last two points
onto the screen.
Line format:
5 colour x1 y1 z1 x2 y2 z2 x3 y3 z3 x4 y4 z4
where
+ colour is a colour code: 0-15, 16, 24, 32-47, 256-511
+ x1, y1, z1 is the position of the first point
+ x2, y2, z2 is the position of the second point
+ x3, y3, z3 is the position of the third point
+ x4, y4, z4 is the position of the fourth point
Here is an example using the optional line command. If we try
to approximate a (cylindrical) stud with a hexagonal prism we
have something like this:
1___________2
/ \
/ \
6/ \3
|\ /|
| \ / |
| \5___________4/ |
\ | | /
\ | | /
\|___________|/
+ The line below 1 should not be drawn because 6 and 2 are on
different sides.
+ The line below 2 should not be drawn because 1 and 3 are on
different sides.
+ The line below 3 should be drawn because 2 and 4 are on the
same side.
+ The line below 4 should not be drawn because 3 and 5 are on
different sides.
+ The line below 5 should not be drawn because 4 and 6 are on
different sides.
+ The line below 6 should be drawn because 5 and 1 are on the
same side.
resulting in the following drawing:
1___________2
/ \
/ \
6/ \3
|\ /|
| \ / |
| \5___________4/ |
\ /
\ /
\_____________/
Colours
Colours are outlined in LEDIT.DOC. Two special values are 16 and 24.
16 is the 'current colour', i.e., whatever colour was specified on the
type 1 line which caused the current line to be executed. Colour 24 is
a complementary colour to the current colour, usually the bright/dark
complementary shade. So if the current colour is dark blue, colour 24
would give bright blue.
Also, colours 256 through 511 are dithered. So if you want to combine
colours J and K, figure your colour value as
colour = (J * 16) + K + 256
The complementary colour of J is used as the complementary colour of
the dithered value. So you can control the edge colour (somewhat) by
switching J and K.
Line type 1's format is:
Line Format:
1 colour x y z a b c d e f g h i part.dat
Fields a through i are orientation & scaling parameters, which can be
used in 'standard' 3D transformation matrices. Fields x, y and z also
fit into this matrix:
| a d g 0 |
| b e h 0 |
| c f i 0 |
| x y z 1 |
so that every point (x, y ,z) gets transformed to (x', y', z') :
x' = a*x + b*y + c*z + x
y' = d*x + e*y + f*z + y
z' = g*x + h*y + i*z + z
or, in matrix-math style:
| a d g 0 |
| X' Y' Z' 1 | = | X Y Z 1 | x | b e h 0 |
| c f i 0 |
| x y z 1 |
21) How can I make ray-traced images of LDraw models?
There are two tools for converting LDraw models to the format of the
ray-tracer POV-Ray. L2p is based on Lutz Uhlmann's very detailed parts
library, LGEO. It is available for DOS and Linux. L3p is based on the
LDraw parts library. Only available for DOS.
Lutz Uhlmann's LGEO tutorial
Lutz Uhlmann's LGEO tutorial can be found at
<URL:http://titan.informatik.uni-bonn.de/%7Euhlmann/tutorial.html>.
Jacob's quick recipe for making ray-traced images of LDraw models
1. Convert your LDraw .DAT files to POV-Ray .INC files with L2P:
> l2p -i -v -t -l my_model.dat my_model
It is important that you process sub-models as well, because L2P
simply converts a reference to a .DAT sub-model to a reference to
a .INC sub-model.
2. Make a copy of the scene file Lutz has included in the package
(l2p_test.pov):
> copy l2p_test.pov my_model.pov
3. Edit the fourth line in your new scene file (the one that says:
#include "l2p_test.inc"). It should refer to the .INC file for
your model instead:
#include "lg_color.inc"
#include "lg_defs.inc"
#include "my_model.inc"
4. Run POV-Ray with the new scene file. This is how I do it in Linux.
There are probably some minor differences when you do it in DOS:
> povray +L/usr/lib/povray/include/ +Llgeo/ +Imy_model.pov
The first +L refers to the POV-Ray libraries, the second +L refers
to the LGEO library, and the +I refers to the scene file.
Bram's additions for Win95 users
In the windows version instead of writing a long command line, you
need to go to Edit Rendering Settings and add the command line options
(+L).
22) How does one map a bitmap onto a LDraw object?
Use BMP2LDRAW, BMP2DAT or Tore's LDraw vector drawing program (see the
answer to question 16) to create a .DAT file with just the image.
Copy the DAT file for the part you are going to add the bitmap to from
the Parts catalog to the Models catalog, and give it a new name.
Insert the bitmap as a part in the new DAT file. Translate and rotate
the bitmap part as appropriate. B
23) How can I get a clear brick in LDraw?
Colour 47 (clear white) works pretty good.
See section 27 for more information on colours.
24) How can I create a part that is not yet in LDraw?
First check if somebody else are working on the part. You can do that
on the parts tracker (see
<URL:http://www3.hmc.edu/%7Ezbenz/parttracker/partlist.shtml>). Steve
Bliss, Jaco van der Molen, and Tore Eriksson present different
approaches to creating parts, and Manfred Moolhuysen has some detailed
advice for using the predefined subparts (without studying math). But
first of all, you should check out which primitives are available (at
<URL:http://hugin.risoe.dk/JJ_Memorial/FAQ/Primitives_Reference>).
When you have finished the part, you should check it for technical
mistakes with l3p -check, and then send it to jjmemorial@geocities.com
so it can be included in the L-CAD parts distribution.
Steve Bliss writes:
Hmm. "Directions for making parts". Hmm. I can't think of directions,
so much as advice. I don't really see how there could be a 1-2-3
cookbook approach. But here are some thoughts:
When you model a part, you need to think in terms of vertices, edges
and surfaces. Your part-file has to provide one or more commands for
each edge and surface. You need to specify these edges and surfaces by
the XYZ position of their vertices. So you have to measure out where
the vertices are. The trick with lego parts is that they are
(typically) built around the familiar sizes of studs and plates (and
bricks). So you often measure parts by comparing them to other parts
(like simple bricks and plates).
The typical way to start drawing a part is to examine the .DAT file
for a similar part. At least, that's the way *I* do it. ;-) Doing an
LEDIT xxxx.DAT will let you step through each line in the part-file,
so you can see what the effects are. And how other people have built
their parts.
Here are some suggestions on what you should check out as you get
started:
1. Study the LDraw language section of the LDraw FAQ. Become very
familiar with the formats, and what they do.
2. Expertise with computer graphics methods is very helpful. You
should at least be comfortable with the concepts of rotating,
translating, and scaling, even if you aren't comfortable with the
theory behind them.
3. Forget about LEdit, except as a sometimes buggy way of stepping
through the part-files you create. Notepad will be your friend for
creating new parts. I also use Excel, LDraw Add-On's Inliner, and
the little Torus Generator I wrote. If you find another tool that
is helpful for parts-modelling, I'd like to know!
4. Learn what's in the ldraw\p\ directory. This directory contains a
number of subpart files that are useful in different parts.
STUD.DAT is used in almost every LDraw part in existence (and most
of the others use STUD2.DAT). The other files are useful
"synthetic primitives", such as rings, discs, cylinders, and
spheres. Some of them are LEGO-specific, such as PEGHOLE.DAT, and
some are very general, such as 1-4DISC.DAT (BTW, the '1-4' means
1/4).
What kind of instructions/information would you like to see? I'd be
happy to answer questions (and I'm sure others would as well), but I
don't have time to write up a big list of instructions right now. Tips
I can provide, but I hate throwing off a bunch on context-free
information which may or may not be relevant.
Tip #1: The LDraw standard for positioning is to center the piece on
X=0 and Z=0. Usually, the top of the part (excluding studs) is set to
Y=0.
Tip #2: Look for repeated elements in a part, which you can write up
as a sub-part file. I find long lists of LDraw commands to be very
confusing. Using subparts can shorten the file, and make things more
comprehensible. In writing my chain-saw blade, my final version used
10 custom files. I used the inliner utility to combine all these files
before publishing.
Tip #3: Use the 0 command-line to insert as many comments as you want.
You can always remove them before publishing, if you don't want
everyone to see your notes. This can really help to organise long
files, making it easier to go back and fix sections later.
Tip #4: Notepad is not very good. Wordpad is better. You may have
another editor you like even more.
I can't think of anything else right now. Ask lots of questions.
Steve
Jaco van der Molen writes:
1. I made a drawing on paper of the basic points and started mapping
these coordinates.
2. Next I used Excel (yes, MS Excel) to define the coordinates of all
other points and combined these into lines and faces.
3. To finish the job, I used Editpad to remove the tabs and replace
them by spaces and there I had it!
Sjaacko
Tore Eriksson writes:
While making a part, I often use different colours so that I can
easily see what areas are still to be covered, if a polygon came out
right, and which one didn't.
You can find an example at
<URL:http://hugin.risoe.dk/JJ_Memorial/FAQ/25a.gif>.
When everything is done, it's easy to set all to colour 16 or 24.
Tore
Manfred Moolhuysen writes:
Examining the existing part file of a basic lego brick also helps you
to understand how part files are made.
Most of them use subparts, handy primitive shapes like cylinders,
circles, disks, and the studs that are on top of or inside the bricks.
You find all the available subparts in the subdirectory P.
The line:
1 16 0 8 0 -6 0 0 0 -12 0 0 0 6 4-4cyli.dat
means you are including a full cylinder wall, a tube with both ends
open. The other #-#cyli.dat subparts are useful if you want just a
part of a cylinder wall, say 3-4cyli.dat for a 270 degrees cylinder
part.
The numbers 0 8 0 tells LDraw to place the cylinder base centred at
the point (X = 0, Y = 8, Z = 0), just like the placing of normal
parts.
The 9 numbers following represent combined information about the
dimensions of the cylinder and its orientation in space. In
mathematics it is called a transformation matrix, but luckily for us
we can tackle this in a "you don't have to know math" way.
To put it simply:
* The pure value of the numbers represent the dimensions.
* The distribution of the numbers over the 9 available positions and
the fact if they are positive or negative represent the
orientation.
In this example the cylinder radius is 6 units (= diameter 12). the
two numbers 6 are responsible for that. If those two numbers were not
equal the result would have been a "squeezed" pipe with an oval
cross-section. The 12 says the cylinder is 12 units high or long.
I have worked out a simple way to deal with the orientation of
subparts, without getting my mind in a numerical twist:
* I make a one line dat file whit the subparts proper dimension, but
no orientation information. Example:
1 16 0 0 0 6 0 0 0 12 0 0 0 6 4-4CYLI.DAT
This is a cylinder with radius 6 hanging down 12 units from the
zero plane.
* I load the one line file in LEdit and give it the right
orientation with the TURN option. Then i save it, and paste the
result into my part file. In this last stage i also give it the
correct insertion point.
You see, no math at all. It also works for all the other subpart
types.
Some examples and detailed instructions:
Create this file, in the LDRAW\MODELS directory:
0
1 16 0 0 0 6 0 0 0 12 0 0 0 6 4-4CYLI.DAT
0
and name it TEST.DAT. View it in LDRAW and see the result.
now change the file in:
0
1 16 0 0 0 6 0 0 0 24 0 0 0 6 4-4CYLI.DAT
0
View the result in LDRAW again. You will see the cylinder is twice as long
now.
now change the file in:
0
1 16 0 0 0 12 0 0 0 24 0 0 0 12 4-4CYLI.DAT
0
View the result in LDRAW again. You will see the cylinder is twice as wide
now.
now change the file in:
0
1 16 50 24 20 12 0 0 0 24 0 0 0 12 4-4CYLI.DAT
0
View the result in LDRAW again. You will see the cylinder has been moved to
a different spot.
Now you have an idea what the numbers do if you change them:
position 3,4 and 5 were 50 24 20 and control the insertion point of the
subpart.
position 6 to 14 were 12 0 0 0 24 0 0 0 12 and control the size of the
subpart.
Changing the order and the signs of the last 9 numbers turns your cylinder,
so it is pointing in another direction. This is what you do in LEDIT.
first change file TEST.DAT back in:
0
1 16 0 0 0 12 0 0 0 24 0 0 0 12 4-4CYLI.DAT
0
We set the numbers on positions 3,4 and 5 to 0 0 0, so the cylinder will
turn around its insertion point.
Start LEDIT, press the ESCAPE-key, press F (stands for file) and L
(for load) Type the file name: TEST.DAT.
line:
1 16 0 0 0 12 0 0 0 24 0 0 0 12 4-4CYLI.DAT
is in the middle of the three lines displayed at the top of the screen. the
line above reads START and the line under reads END.
Press ESCAPE again, Press T (for turn) and X (for x-axis).
Type the angle: 90
On the screen it seems the cylinder has disappeared, but if you press
PAGE-UP followed by PAGE-DOWN the cylinder is redrawn in its new
position. As you can see the cylinder is laying on its belly now.
First save the file: press the ESCAPE-key, press F (for file) and S
(for save). Then open it in your text editor or in windows and cut and
paste the line in the file where you need it.
If you turn the subpart around Z instead of X it is turned into
another direction. Turning around Y is just like spinning the cylinder
around its center, you see no difference at all.
If your file has more than one subpart in it, you can select the one
you are going to turn with the PAGE-DOWN and PAGE-UP keys. It must be
the middle one of the 3 lines displayed at the top of the screen.
Now try to do something similar with RECT.DAT, make the file
0
1 16 0 0 0 40 0 0 0 1 0 0 0 20 RECT.DAT
0
Just start to play and fiddle a little bit with the numbers on
positions 6, 10 and 14, and see what results you get.
M. Moolhuysen
25) How can I find the numbers for a view in LDraw?
1. Fire up LEdit.
2. Choose the front view (/VF).
3. Rotate the default piece until it's sitting the way you want to
view.
4. Look at the part-line in the top of screen (between the START and
END lines).
5. Write down the 6th through 14th numbers (everything after the 1 0
0.0 0.0 0.0).
6. Exit LEdit.
7. Run LDraw with the command LDRAW -a6th,7th,8th,...,14th file.dat
(using the numbers you wrote down after the -a option).
26) Where does LDraw look for files
LDraw looks for .DAT files in the following catalogs, in the order
they are listed.
1. The current catalog.
2. The P catalog.
3. The PARTS catalog.
4. The MODELS catalog.
27) What is the colour code for ... ?
The following list is based on the documentation for LDraw, on
discussions on the L-CAD mailing list, and on a compilation of RGB
colour values by Todd Lehman (LDraw is not using the RGB values listed
here). I have added some <red, green, blue, alpha> codes for rendering
transparent parts in POV-Ray and other ray-tracing packages. Most of
them are copied from Lutz Uhlmann's LGEO package.
Black
LDraw: 0
RGB: 51 51 51
Blue
LDraw: 1
RGB: 0 51 178
Brown
LDraw: 6
RGB: 102 51 0
Chrome
LDraw: 383
RGB: 204 204 204
Cyan
LDraw: 11
Dark cyan
LDraw: 3
Dark grey
LDraw: 8
RGB: 102 102 88
Dark pink
RGB: 255 51 153
Electrical contacts
LDraw: 494 (yellow)
RGB: 204 204 204 (chrome)
Glow in the dark
RGB: 224 255 176
Gold
LDraw: 334
RGB: 240 176 51
Green
LDraw: 2
RGB: 0 127 51
Grey
LDraw: 7
RGB: 153 153 153
Light blue
LDraw: 9
RGB: 0 128 255
Light green
LDraw: 10
RGB: 51 255 102
Light purple
RGB: 224 204 240
Light red
LDraw: 12
Light yellow (Belville)
LDraw: 495
RGB: 255 255 128
Lime green (Blacktron II)
RGB: 173 221 80
Magenta
LDraw: 5
Mint green (Belville)
LDraw: 431
Orange
LDraw: 462
Pastel green
RGB: 102 240 153
Pink
LDraw: 13
RGB: 255 176 204
Purple
RGB: 153 51 153
Purple blue
RGB: 76 0 204
Red
LDraw: 4
RGB: 204 0 0
Silver
LDraw: 383
RGB: 204 204 204
Tan
LDraw: 382
RGB: 204 170 102
Transparent (white)
LDraw: 47
POV: <1.0, 1.0, 1.0, 0.9>
Transparent dark blue
LDraw: 33
RGB: 0 0 153
POV: <0.00, 0.00, 0.94, 0.90>
Transparent green
RGB: 0 80 24
POV: <0.00, 0.83, 0.00, 0.90>
Transparent green-yellow (?)
RGB: 204 255 0
POV: <0.80, 1.00, 0.00, 0.90> or <0.85, 1.00, 0.00, 0.85>
Transparent light blue
LDraw: 41
RGB: 153 192 240
POV: <0.75, 0.90, 1.00, 0.95>
Transparent orange
RGB: 255 102 0
POV: <1.00, 0.68, 0.00, 0.80>
Transparent red
LDraw: 36
RGB: 204 0 0
POV: <1.00, 0.20, 0.00, 0.90>
Transparent yellow
RGB: 240 196 0
POV: <0.99, 0.96, 0.00, 0.90>
White
LDraw: 15
RGB: 255 255 255
Yellow
LDraw: 14
RGB: 255 229 0
28) Runtime Error 200 ???
LEdit crashes with runtime error 200 on some fast machines. Some delay
routines which use a fixed value to count down just resolve to fast on
these machines. There is a solution to this problem at
<URL:http://hugin.risoe.dk/JJ_Memorial/rte200fx.html>.
If you can read German, you can also go to
<URL:http://www.heise.de/ct/ftp/pcconfig.shtml> and download
bppatch.zip, which will do this job for you.
29) Runtime Error 003 ???
The hidden message in this code is "path not found". It occurs if the
path to LDraw contains "long" (more than eight letters) catalog names.
The problem can be solved by moving LDraw to a directory named
C:\LDraw.
30) Can I get LDraw to put the BMP files somewhere else?
No, but you can move the files with a command like this:
C:\LDRAW> move BITMAPS\MODEL-01.BMP D:\Where\I\Want\My\Pictures
31) What is the parts voting procedure?
Part voting is democratic and is handled by Terry Keller, there is
usually a vote after the 15th of every month. Terry is very respected
by the group, so sometimes he makes decisions on ideas that don't
warrant a vote (or basically gives us the final word). Primitives are
handled by a committee.
_________________________________________________________________
Even though I try to, I can't know everything, so please write me, if
you have corrections or additions to the FAQ.
Jacob
Latest update: February 9th 1999.
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