[Plugin] FreeDXF Importer

toxicvoxel

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

@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

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

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

@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

@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

@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

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

New Version 0.51

Improved ELLIPSE method
Added import of TEXT entities.

See first post for download.

1859.dxf

1859.skp

driven

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

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

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

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

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

TIG

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

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

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...

Jim

@thomthom said:

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

Currently TEXT and MTEXT are imported as 3D text (but with zero thickness.) The Font defaults to low-quality Arial. Texts respect newlines, position, height, font (if installed?), bold, and italic styles. Roation is not yet complete. Tects color is always black for now.

I had planned an option to import text as SketchUp screen text. In fact that's the easiest way to import it and the most economical as far as geometry.

@thomthom said:

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.

Good idea - will implement.

@thomthom said:

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

FreeDXF does not consider units at the moment, so every import would be considered as being in Inches.

driven

hi Jim, here's a mac screenshot,

I've got an archive of these simple reduction gear dxf's and it opens them a threat...

it's particularly useful being able to specify circle and arc segment counts, the v7 SU importer bought these in a such low quality, I couldn't use them.

it splits out into layers, but doesn't group those items, I haven't read the script yet but is that addable?

i.e. each layers geometry is also a group so it doesn't stick on first opening with all layers on.

also does it do faces?, I'm not sure if this test file has any... a lot of them don't.

cheers

john

enough to build a 3d cycloidal drive...

Jim

@driven said:

it splits out into layers, but doesn't group those items, I haven't read the script yet but is that addable? i.e. each layer's geometry is also a group so it doesn't stick on first opening with all layers on.

Yes, I think it's addable. I was using SketchUp Pro's dxf importer as my example; which does not group geometry by layer. But it seems like a better way to import geometry seeing as cad layers are more like SketchUp Groups than SketchUp Layers. So would all entities in the group be on the cad layer, or just the group on the cad layer with the raw geom on Layer0?

@driven said:

also does it do faces?, I'm not sure if this test file has any... a lot of them don't.

Not really yet. It does import 3DFACE entities, but I think they are not common in dxf's.

I appreciate the feedback. (send test files.)