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  #1  
Old 09-14-2021, 07:34 AM
Laurence Finston Laurence Finston is offline
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Polyhedron models: Small Rhombicosidodecahedron

Hello,

I have just finished plans for a paper or cardboard model of a Small Rhombicosidodecahedron: https://www.gnu.org/software/3dldf/g...all_rhombi.pdf

The webpage is here: The GNU 3DLDF Polyhedron Models Page
There are other, older models on this page as well. i believe the last time I worked on them was 2011.

General instructions are here: https://www.gnu.org/software/3dldf/g...s/plmdinst.pdf

The net is from the book Mathematical Models by H.M. Cundy and A.P. Rollett, 2nd edition, Oxford University Press, 1961, p. 111. I'm not sure whether it's in print or not; I think probably not.

It's been one of my favorite books ever since I discovered it by chance at the library as a child. After having checked it out many times over the years, I finally found it for sale at a used book store.

Since there is no text on this model, generating the plans in different sizes is no problem. There is a single parameter that governs the size of the model of the polyhedron itself, namely the radius of the surrounding circle of the pentagon. For the tabs, there are a couple of parameters governing the size, shape and placement, but it would easy to adjust them for different sizes of the model.

There are some extra tabs which will need to be cut off. This shouldn't be a problem. In a couple of places, I wasn't quite sure which were needed and which weren't. It's better to have too many than too few. However, if any are missing, a piece of paper can be used as a substitute; strictly speaking, they're just a convenience.

I chose approximately the largest size for which the plans for the entire model can be printed on a single DIN A3 piece of paper.

There are interesting ways of coloring the faces of polyhedra in order to bring out the various kinds of symmetry present, depending on the polyhedron. Unfortunately, I've never gone further into this than finding some references which I no longer remember. In addition, it's been a long time since I've worked on this material and I need to brush up my geometry.

I have one book in German which goes into this topic: Farbige Parkette by K. Bongartz, D. Mertens, W. Borho and A. Steins. "Farbige" or "farbig" means "colored" and "Parkette" are tessellations or tilings of the plane and polyhedra are closely related to tessellations. However, I doubt very much if this book is in print and it's probably not as widely available as Cundy and Rollett.

If I learn a good way of coloring the present model I will update the plans on the website, as I will do for any other additions or corrections.

Any feedback would be much appreciated.

Laurence Finston
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  #2  
Old 09-21-2021, 10:39 AM
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asettico asettico is offline
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Really interesting, Laurence.
Thank you for this contribute, I also installed the 3dldf-doc package!
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  #3  
Old 09-21-2021, 12:31 PM
Laurence Finston Laurence Finston is offline
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Quote:
Originally Posted by asettico View Post
Really interesting, Laurence.
Thank you for this contribute, I also installed the 3dldf-doc package!
Thank you, asettico. I wouldn't bother with the 3dldf-doc package. It's quite out of date. The most recent edition of the manual is 1.1.5.1, which is probably the one in that package. I have seen that that package exists, e.g., on my Ubuntu system, but I had nothing to do with putting it together. Nobody told me that they'd done it and I don't know who did. I've never looked to see what's in it.

The manual documents an older version of the GNU 3DLDF program/package, before it was interactive. For a number of years, it has implemented a sort of "scripting language", based on the METAFONT and MetaPost languages, but not sharing any code with those programs. The manual documents a state where GNU 3DLDF was more like a C++ library where the user had to write C++ code to make drawings. Now, he or she just needs to write code in the GNU 3DLDF language, run 3dldf, then MetaPost, TeX and then dvips to make a PostScript file or dvipdfmx to make a PDF file.

I need to rewrite the manual completely and I've made a start on this. I figure it will take about a year to finish it, though. However, there are lots of example files on the website:
The GNU 3DLDF Website

The old manual is still potentially interesting if one wants to know how the program is implemented. However, I've added a lot since it was written.

If you want to try using it, I recommend downloading the entire package from Savannah, which is a platform run by the GNU Project of the Free Software Foundation. It's sort of like GitHub, where I incidentally have some other programs which are also Free Software but not part of the GNU Project.

The main page on Savannah is here: 3DLDF - Summary [Savannah]

You can "clone" the package like this:
git clone https:XXX XXX//git.savannah.gnu.org/git/3dldf.git (Remove "XXX XXX" to get the command --- I had to put them in to keep the forum software from making a link)
The page with info about the git repository is here: 3DLDF - Git Repositories [Savannah]

If you feel like trying it out and need any help getting it up and running, you could subscribe to the mailing list at

help-3dldf Info Page
or just send me an email. My email address is listed here:

The GNU 3DLDF Website

Thank you for your interest and please let me know if I can help in any way.

Laurence
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Old 09-22-2021, 12:54 AM
Algebraist Algebraist is offline
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Very nice models Laurence and kind of you to release.
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Old 09-22-2021, 01:27 AM
Laurence Finston Laurence Finston is offline
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Thank you, Algebraist.
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  #6  
Old 09-24-2021, 10:22 AM
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asettico asettico is offline
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Quote:
Originally Posted by Laurence Finston View Post
Thank you, asettico. I wouldn't bother with the 3dldf-doc package. It's quite out of date. The most recent edition of the manual is 1.1.5.1, which is probably the one in that package. I have seen that that package exists, e.g., on my Ubuntu system, but I had nothing to do with putting it together. Nobody told me that they'd done it and I don't know who did. I've never looked to see what's in it.
I currently use Linux Mint, based on Ubuntu, the package version is 2.0.3+ndfsg-4, containing the document version 2.0, as of 2013, in PDF and HTML format.
But it's still interesting. Unfortunately I have no time to entertain me with it, but it's a good source of information.

Quote:
Originally Posted by Laurence Finston View Post
The manual documents an older version of the GNU 3DLDF program/package, before it was interactive. For a number of years, it has implemented a sort of "scripting language", based on the METAFONT and MetaPost languages, but not sharing any code with those programs. The manual documents a state where GNU 3DLDF was more like a C++ library where the user had to write C++ code to make drawings. Now, he or she just needs to write code in the GNU 3DLDF language, run 3dldf, then MetaPost, TeX and then dvips to make a PostScript file or dvipdfmx to make a PDF file.

I need to rewrite the manual completely and I've made a start on this. I figure it will take about a year to finish it, though. However, there are lots of example files on the website:
The GNU 3DLDF Website

The old manual is still potentially interesting if one wants to know how the program is implemented. However, I've added a lot since it was written.

If you want to try using it, I recommend downloading the entire package from Savannah, which is a platform run by the GNU Project of the Free Software Foundation. It's sort of like GitHub, where I incidentally have some other programs which are also Free Software but not part of the GNU Project.

The main page on Savannah is here: 3DLDF - Summary [Savannah]

You can "clone" the package like this:
git clone https:XXX XXX//git.savannah.gnu.org/git/3dldf.git (Remove "XXX XXX" to get the command --- I had to put them in to keep the forum software from making a link)
The page with info about the git repository is here: 3DLDF - Git Repositories [Savannah]

If you feel like trying it out and need any help getting it up and running, you could subscribe to the mailing list at

help-3dldf Info Page
or just send me an email. My email address is listed here:

The GNU 3DLDF Website
I know Savannah, I will try to take a look at it. I would like to play with the library, time permitting...

Quote:
Originally Posted by Laurence Finston View Post
Thank you for your interest and please let me know if I can help in any way.

Laurence
It's always a pleasure to put the hands in GNU projects. In the past I had the privilege to meet mr. Stallman, an eclectic genius and a sensible person, despite the appearences.
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  #7  
Old 09-24-2021, 11:35 AM
Laurence Finston Laurence Finston is offline
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I've never met Richard Stallman but I've had occasional friendly contact with him about my (2) GNU packages.

I would only recommend GNU 3DLDF to people who are either already using TeX and/or MetaPost or METAFONT or are interested in doing so. Also, only for people who want to program drawings rather than using a mouse and a graphical user interface.

When I learned to use AutoCAD a long time ago, I quickly started to use AutoLISP for this purpose. At the time, AutoCAD was very expensive. I don't know what it costs now. GNU 3DLDF was and is meant to be a program for making technical drawings which is free, i.e., free as in speech AND free as in beer.

Otherwise, there are a lot of other 3D graphics programs out there and possibly a better choice, depending on what one wants to do.

Obviously, as one person alone I can't compete with the makers of AutoCAD. For example, I have no intention of ever programming anything for calculating stress on various materials or things like that.

However, the basic things one needs to make technical drawings can be programmed with a reasonable amount of effort.

I did my first polyhedron models, which I actually built, using AutoCAD. Unfortunately, they're packed away in a box far at the back of my basement. Otherwise I'd post photos of them. I must have the AutoCAD files too, somewhere.
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  #8  
Old 09-24-2021, 11:43 AM
Laurence Finston Laurence Finston is offline
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Quote:
Originally Posted by asettico View Post
I know Savannah, I will try to take a look at it. I would like to play with the library, time permitting...
It used to only be a library. Now, it's first and foremost an interactive program that can be called from the command line. It will either read commands in the 3DLDF language from a file, from standard input, or both.

However, it's possible to build it in such a way that it creates a shared library. 3DLDF itself (i.e., the 'main' function of the program) uses this library, but it's also possible for other programs to link to it. The library contains definitions of classes like 'Point', 'Path', 'Circle', 'Sphere', etc., and functions for operating on them.

It's also possible to build the package without creating a shared library. This is faster.
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