[Plugin] FreeDXF Importer

Gruff · 19 Oct 2009, 08:14

Nice list of specs you found there Jim. Are you writing against the 2010 version?

I'd recommend writing it to the earliest version of DXF that is still supported under 2010.
One heck of a lot of users are still using 2006 and earlier.

~Gruff

toxicvoxel · 19 Oct 2009, 08:21

Jim,
Which DXF entity types do you aim to support eventually?

thomthom · 19 Oct 2009, 08:23

@gruff said:

@thomthom said:

Nice list of specs you found there Jim. Are you writing against the 2010 version?

I'd recommend writing it to the earliest version of DXF that is still supported under 2010.
One heck of a lot of users are still using 2006 and earlier.

~Gruff

hm... I could see the logic of that if you where writing DXF format. But we're talking about reading DXF format. I'd think that you'd want to be able to read recent formats.
Is the DXF format constructed in such a way that parsing a DXF file with the newest spec will allow it to read older versions?

toxicvoxel · 19 Oct 2009, 08:35

I haven't used a new version of AutoCAD for some time but historically solid objects where defined as encoded strings within the DXF export file, rendering it only partially 'open'. Not sure if this situation has changed but it may be a challenge to support all current AutoCAD entity types.

Has anybody explored the cost of using the libraries from the Open Design Alliance?
(http://www.opendesign.com/)

Jim · 19 Oct 2009, 13:16

@toxicvoxel said:

Jim,
Which DXF entity types do you aim to support eventually?

Right now, it has calls to handle: LINE ARC CIRCLE VERTEX SEQEND ELLIPSE BLOCK ENDBLK INSERT POLYLINE 3DFACE

Although some do not work properly. You may have noticed it creates an output file named freedxf_types.txt in your plugins folder. It is a breakdown of found and supported command blocks for the imported file for inspection, one per line.

@unknownuser said:

Nice list of specs you found there Jim. Are you writing against the 2010 version?

I didn't look at all the version - I don't know what the difference is between them. I arbitrarily opened the 2000 version because it had online html and started coding. I don't think the format will have changed - i.e. the parser should be forward compatible. What may change is how each entity type is handled, or new types introduced. I'm probably wrong.

I'm not sure how useful it will be in the end. I hosted in on bitbucket to encourage hacking on it. If mercurial/bitbucket isn't your thing, I can do a git/github repo also.

TIG · 19 Oct 2009, 13:40

In passing... I am working on a parallel DXF TEXT importer that imports any text/mtext/attributes in the DXF - as flat 3D text using the size, font, formating etc...

toxicvoxel · 19 Oct 2009, 14:53

Jim,
I think it would be imperative to support polyface meshes as minimal functionality for this plugin as so many formats export faces using this structure.
This would also potentially provide a logical optional construct to map against sketchup groups, which maps to blocks in the current importer/exporter.

Your efforts are appreciated.

Gruff · 22 Oct 2009, 21:00

@thomthom said:

hm... I could see the logic of that if you where writing DXF format. But we're talking about reading DXF format. I'd think that you'd want to be able to read recent formats.
Is the DXF format constructed in such a way that parsing a DXF file with the newest spec will allow it to read older versions?

No. Quite the reverse.

If we are only talking 2D/3D wireframe standard elements then I do not think it would be a problem. Getting into 3D Surfaces and Solids could very well be a version issue.

AutoCad typically allows you to save a DXF (or DWG) to 3 or 4 earlier versions of the file format.

If Jim's importer can only read 2010 DXF and I only have ACAD version 2004 then Jim's importer may be expecting data structures that simply do not exist in the 2004 version. I would not be able to use his utility.

If Jim writes his importer to read 2004 DXF files then someone with version 2010 of ACAD can always save his file to the older version for Jim's program.

Of course the smartest move would be to have his program read the version and use the appropriate version translator. But that is a tall order I think.

thomthom · 22 Oct 2009, 21:10

@gruff said:

If Jim's importer can only read 2010 DXF and I only have ACAD version 2004 then Jim's importer may be expecting data structures that simply do not exist in the 2004 version. I would not be able to use his utility.

You say "may"... Have you studied the format? Or is it a guess?

I was thinking that it'd build upon the previous versions. That a 2010 reader would be able to read previous versions. Why would you extend a format such that it changes an existing implementation? That just seem to create more problems.

Gruff · 25 Oct 2009, 17:48

@thomthom said:

@gruff said:

Have you studied the format? Or is it a guess?

I have written translators for several CAD file formats and a few simple converters for DXF. Most recently a DXF exporter for Solidworks to SigmaNest. (Creating additional geometry not in SW on export)

It is the nature of file formats to evolve to support more features and to crop structures that are no longer necessary for the latest version. If I recall correctly AutoCAD version 1.0 came out in 1982.
DXF was defined sometime thereafter... 1984 or so. Quarter of a century would be a long time to remain backward compatible for a privately held file format.

As I said earlier though. If all Jim is going to support is wireframe then it shouldn't be an issue.

honoluludesktop · 27 Oct 2009, 20:07

Hi Jim, Am watching this topic for your progress. Btw, I see that you bookmarked the html for Dxf definitions. I did the same thing until I realized "Dah!", that I could bookmark the pdf on line as well. Sigh, old habits die hard:-(

Jim · 3 Jul 2011, 02:49

New Version 0.51

Improved ELLIPSE method
Added import of TEXT entities.

See first post for download.

1859.dxf

1859.skp

driven · 3 Jul 2011, 12:13

hi Jim,

should it work on mac?

trying to load your .dxf gives

Error; #<TypeError; reference to deleted Group>
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;466;in `transform!'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;466;in `draw_text'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;133;in `draw'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;92;in `main'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;91;in `each'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;91;in `main'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;503
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;466;in `call'
/Library/Application Support/Google SketchUp 8/SketchUp/Plugins/freedxf/freedxf.rb;466

haven't time to look further at the moment, so thought I'd ask first.
john

Jim · 3 Jul 2011, 18:19

Thanks, John. I started seeing that error too, although not everytime. It's really baffling because it appears to have started when I made some changes in what should be an unrelated method. I will trap the error, but I am still not sure what exactly is happening. There will be an update (or 2) today.

thomthom · 7 Jul 2011, 13:38

Does bitbucket reflect the latest changes?

I went looking at it to work out what it imported DXF TEXT entities as. Text entity in SketchUp?

thomthom · 7 Jul 2011, 13:47

Ok - tried it out. I see the text comes in as simple geometry. Would be useful with an option to get the text as native Text elements. And/or when the text is imported as geometry, add the text value to an attribute so it can be read by other Ruby scripts.

thomthom · 7 Jul 2011, 13:56

Does it handle units at all? Or does it assume inches?

TIG · 7 Jul 2011, 14:20

My importDXFtext.rb ideas could be cannibalized into this tool to add the DXF's text in 2d 3dText groups, using available fonts or defaulting [mine uses Arial.ttf if the font is not in one that's listed] - my tool also replicates the [M/D]text/attribute's coded-symbols, colors, size etc wherever possible - also you could easily add an attribute for the text's 'string'...

thomthom · 7 Jul 2011, 15:01

I managed to hack this plugin for my need. Placed Text objects. Then I could use them to extract their insertion points and move them to the height given in the text - resulting in a point cloud, which I used TIG's Triangualte Points (modification of Didier) to generate a terrain mesh.

phew

At least now I got an accurate terrain. Thanks for all your scripts.

TIG · 7 Jul 2011, 15:09

Ages ago I wrote an AutoLisp tool to run in your CAD DWG and read 'flat' spot-height pieces of D/Mtext and move them in the Z to suit their given 'elevation' taken from the text's string into a float, and also add a 'point' at the text's origin - you can then export those as a point-cloud DXF for use in your SKP... to meshify it...
If the lisp would be of any help let me know and I can PM it...