(2022-07-06, 12:31)Cam's Bricks Wrote: I am pretty sure the answer is "no, no, not ever, no thanks, that is a terrible idea" BUT I wanted to ask if there is support for variables in the LDraw file format? 

It would probably take support of all the editors and renders which is probably causing someone's eyebrows to make odd shapes as even type this out  

I am someone who enjoys the "make it once and for all use cases", so the pragmatic nature of making a lot of similar parts that have one or two changes for each iteration feels quite bothersome.

(2022-07-06, 15:20)Max Murtazin Wrote: I'm not sure how this can be useful, any examples?

(2022-07-06, 15:20)Max Murtazin Wrote: I'm not sure how this can be useful, any examples?

(2022-07-06, 16:57)Orion Pobursky Wrote: While this is a good idea, it would break backwards compatibility in a huge way.

In my (long neglected) LPov project, I created a POV-Ray macro to programmatically create plates and bricks in much the same way as you describe above.

(2022-07-06, 16:43)Cam's Bricks Wrote: At a basic level something as simple as bricks and plates could be "automated" in this fashion. 

You would have a line type that is used to define a variable. That variable can be used in the part where repetitive dimensions are used or sub-parts are called or any number of other useful calculation points. 

If we look at 3005.dat Brick 1 x 1 we see that the number 24 all over the file:

Code:

1 16 0 24 0 6 0 0 0 -20 0 0 0 6 box5.dat

4 16 10 24 10 6 24 6 -6 24 6 -10 24 10
4 16 -10 24 10 -6 24 6 -6 24 -6 -10 24 -10
4 16 -10 24 -10 -6 24 -6 6 24 -6 10 24 -10
4 16 10 24 -10 6 24 -6 6 24 6 10 24 10

1 16 0 24 0 10 0 0 0 -24 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

Now if we look at 3024.dat Plate 1 x 1 we see it is the same exact file but with every instance of 24 replaced with 8:

Code:

1 16 0 8 0 6 0 0 0 -4 0 0 0 6 box5.dat

4 16 10 8 10 6 8 6 -6 8 6 -10 8 10
4 16 -10 8 10 -6 8 6 -6 8 -6 -10 8 -10
4 16 -10 8 -10 -6 8 -6 6 8 -6 10 8 -10
4 16 10 8 -10 6 8 -6 6 8 6 10 8 10

1 16 0 8 0 10 0 0 0 -8 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

If variables could be used then making both parts would be as simple as adding a line like this and changing the line to equal 8 or 24 or 48 or whatever we want without changing anything else in the file:

Code:

0 !VAR "height" = 24

1 16 0 "height" 0 6 0 0 0 -20 0 0 0 6 box5.dat

4 16 10 "height" 10 6 "height" 6 -6 "height" 6 -10 "height" 10
4 16 -10 "height" 10 -6 "height" 6 -6 "height" -6 -10 "height" -10
4 16 -10 "height" -10 -6 "height" -6 6 "height" -6 10 "height" -10
4 16 10 "Height" -10 6 "height" -6 6 "height" 6 10 "height" 10

1 16 0 "height" 0 10 0 0 0 -"height" 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

This is a simple use case and I would not expect to be able to do math in these lines except for adding "-" to make it negative as needed to meet the BFC rules. Doing math would be bad for rounding errors unless the standard defined a calculation method to be used by all editors and renders.

My more advanced use case is that I want to make train wheels of various sizes and combinations but I would like to write the file once then just change a few variables (radius, subfile call(s), etc) in each of the files without having to type it all again or copy/paste and have errors.

(2022-07-06, 16:43)Cam's Bricks Wrote: At a basic level something as simple as bricks and plates could be "automated" in this fashion. 

You would have a line type that is used to define a variable. That variable can be used in the part where repetitive dimensions are used or sub-parts are called or any number of other useful calculation points. 

If we look at 3005.dat Brick 1 x 1 we see that the number 24 all over the file:

Code:

1 16 0 24 0 6 0 0 0 -20 0 0 0 6 box5.dat

4 16 10 24 10 6 24 6 -6 24 6 -10 24 10
4 16 -10 24 10 -6 24 6 -6 24 -6 -10 24 -10
4 16 -10 24 -10 -6 24 -6 6 24 -6 10 24 -10
4 16 10 24 -10 6 24 -6 6 24 6 10 24 10

1 16 0 24 0 10 0 0 0 -24 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

Now if we look at 3024.dat Plate 1 x 1 we see it is the same exact file but with every instance of 24 replaced with 8:

Code:

1 16 0 8 0 6 0 0 0 -4 0 0 0 6 box5.dat

4 16 10 8 10 6 8 6 -6 8 6 -10 8 10
4 16 -10 8 10 -6 8 6 -6 8 -6 -10 8 -10
4 16 -10 8 -10 -6 8 -6 6 8 -6 10 8 -10
4 16 10 8 -10 6 8 -6 6 8 6 10 8 10

1 16 0 8 0 10 0 0 0 -8 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

If variables could be used then making both parts would be as simple as adding a line like this and changing the line to equal 8 or 24 or 48 or whatever we want without changing anything else in the file:

Code:

0 !VAR "height" = 24

1 16 0 "height" 0 6 0 0 0 -20 0 0 0 6 box5.dat

4 16 10 "height" 10 6 "height" 6 -6 "height" 6 -10 "height" 10
4 16 -10 "height" 10 -6 "height" 6 -6 "height" -6 -10 "height" -10
4 16 -10 "height" -10 -6 "height" -6 6 "height" -6 10 "height" -10
4 16 10 "Height" -10 6 "height" -6 6 "height" 6 10 "height" 10

1 16 0 "height" 0 10 0 0 0 -"height" 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

This is a simple use case and I would not expect to be able to do math in these lines except for adding "-" to make it negative as needed to meet the BFC rules. Doing math would be bad for rounding errors unless the standard defined a calculation method to be used by all editors and renders.

My more advanced use case is that I want to make train wheels of various sizes and combinations but I would like to write the file once then just change a few variables (radius, subfile call(s), etc) in each of the files without having to type it all again or copy/paste and have errors.

(2022-07-06, 17:03)Cam's Bricks Wrote: I am not asking to change anything. I am glad I am not the only one to have thought of this. 

I was more or less doing a check to make sure there wasnt some hidden feature to do this kind of programing in the files before I do it outside the ldraw format and then export to dat.

(2022-07-06, 16:43)Cam's Bricks Wrote:

Code:

0 !VAR "height" = 24
1 16 0 "height" 0 6 0 0 0 -20 0 0 0 6 box5.dat

4 16 10 "height" 10 6 "height" 6 -6 "height" 6 -10 "height" 10
4 16 -10 "height" 10 -6 "height" 6 -6 "height" -6 -10 "height" -10
4 16 -10 "height" -10 -6 "height" -6 6 "height" -6 10 "height" -10
4 16 10 "Height" -10 6 "height" -6 6 "height" 6 10 "height" 10

1 16 0 "height" 0 10 0 0 0 -"height" 0 0 0 10 box5.dat

1 16 0 0 0 1 0 0 0 1 0 0 0 1 stud.dat

(2022-07-06, 21:10)Roland Melkert Wrote: You could (should?) do this using a new meta, especially since you would need to extend existing software in order to use it anyway.

Something like:

Code:

!VAR "height" = 24
!VAR 1 16 0 "height" 0 6 0 0 0 -20 0 0 0 6 box5.dat

You Could also loose the quotes (I always hate those) by defining grammar for the variable name, for example ([a-zA-z]+[a-zA-Z0-9]*)  (case insensitive if needed)

(2022-07-06, 17:17)Philippe Hurbain Wrote: You may want to try to track this...
https://news.lugnet.com/cad/?n=13657

(2022-07-06, 17:14)Orion Pobursky Wrote: Here's the link to my POV-Ray macros for bricks, plates, tiles, and Technic bricks.
https://github.com/billthefish/LDrawPOV/blob/master/LPov/macros.inc

(2022-07-06, 12:31)Cam's Bricks Wrote: I am pretty sure the answer is "no, no, not ever, no thanks, that is a terrible idea" BUT I wanted to ask if there is support for variables in the LDraw file format? 

It would probably take support of all the editors and renders which is probably causing someone's eyebrows to make odd shapes as even type this out  

I am someone who enjoys the "make it once and for all use cases", so the pragmatic nature of making a lot of similar parts that have one or two changes for each iteration feels quite bothersome.

(2022-07-06, 12:31)Cam's Bricks Wrote: I am pretty sure the answer is "no, no, not ever, no thanks, that is a terrible idea" BUT I wanted to ask if there is support for variables in the LDraw file format?
I am someone who enjoys the "make it once and for all use cases", so the pragmatic nature of making a lot of similar parts that have one or two changes for each iteration feels quite bothersome.

(2022-07-08, 16:07)Max Murtazin Wrote: I would like to see this being adopted as an optional feature, maybe even one day this growing into smth like an internal ldraw scripting language, since stuff like this would probably be really neat for use in custom parts and stuff. 

For example, what I could see being a thig are also matrix variables, that could probably be applied to the line after them with a meta command. All such QOL stuff

Also, with those ideas, I could also imagine something like a "compiler" of LDraw files using those features into a proper LDraw file