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DXF Documentation

Feb 4, 2013 at 4:05 PM
This looks like a really great project. I've also done some DXF creation coding, but I was frustrated by the lack of documentation (that I could find). I was wondering if you all could recommend any documentation.

(Sorry if this is off-topic.)
Feb 4, 2013 at 8:05 PM
Edited Feb 4, 2013 at 9:34 PM
Documentation? The only real documentation you can find is the one you can download from the official Autodesk web site, and when you start to dig it it becomes more and more obscure. Most of the time an internet search will not take you very far and usually it is realated with AutoLISP.

My knowledge of dxf comes from my long time expirience with AutoCAD, from the old MS-DOS days, and that makes almost twenty years. I done programming with AutoLISP, vba, and .net ARX; and the knowledge of the AutoCAD drawing in and outs is what makes you understand how the dxf works.

A dxf file is assumed to be a representation of the internal drawing database and here is where most of the problems and the inconsistencies come from. The AutoCAD is an old program, many versions have been appearing through the years and in the old days the 3d capabilities where called 2d and a half. I am sure, nowadays, there are parts of the AutoCAD code that nobody understands anymore.

Probably you will not find much help besides trying to clarify specific questions on your problems.

Feb 4, 2013 at 9:37 PM
That's what I was afraid of. I'm assuming that the older versions are easier to learn, for example R14? Do you have any suggestions of where to start for someone that wants to learn?
Feb 5, 2013 at 10:42 PM
Where to start depends a lot on how much do you know. First a good knowledge of AutoCAD is not only recommended but essential, then at you can find a couple articles on how to read and write dxf files. They are very, very basic but they will show you the beginning. But probably if you have ended here, you have already done your search. From here you are pretty much alone, but nothing beats the good old hacking habits, save a file, load it with your favorite text editor to try to understand its structure, modify a value, and finally load it again to see what happens.

Although older dxf versions are easier to learn, for example you do not need to keep track of handles, if you develop a program to write dxf files for older versions it will need lots of changes to be able to comply with newer versions. This is one of the main reasons why I decided to drop support for R12 dxf versions and concentrate my efforts with AutoCAD2000 and later.