Subject:
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Re: DAT to DXF again
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Newsgroups:
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lugnet.cad.dev
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Date:
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Mon, 7 Oct 2002 22:50:41 GMT
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Viewed:
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679 times
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In lugnet.cad.dev, Manfred Moolhuysen writes:
> In lugnet.cad.dev, Don Heyse writes:
> > Personally, I wish someone would follow the directions on this page to
> > create a 2x2 brick in autocad and then make it into an AutoCAD block.
> >
> > http://homepage.dtn.ntl.com/terry.rawkins/acad/solids/lego.htm
> >
> > Then export the block as a DXF and post it to lugnet so we can see
> > what the DXF file contains. Finally build a little wall with 2 or 3
> > bricks and export that as a DXF file so we can see how DXF uses the
> > blocks in a file to build something. It's one thing to read some DXF
> > specs, but a real world example is so much easier to take apart and
> > understand.
>
> I would like to discuss this because I'm not sure that would be the best
> path to follow. Translating (AutoCad) volume models into (Ldraw) face models
> could proove to be difficult. Maybe you're better off to build the Autocad
> model with faces also, and make a set of AutoCad Blocks that have a 1 on 1
> relationship with Ldraw Primitives, preferably with identical names. Just
> like Primitives, AutoCad Blocks can be scaled along all three axels
> indepenently and rotated in any direction. In Autocad the orientation of a
> block in space is described with a origin point and a normal vector, so I
> guess you could calculate a complete Ldraw matix from those two components.
Can you make an AutoCAD block out of more primitive AutoCAD blocks?
I don't know. That's why I'd like see some simple examples exported
to DXF from AutoCAD. I don't really care whether an AutoCAD version
of the parts uses volumes or faces, whatever is easier to *build* with
in AutoCAD. As you said, as long as the names match 1 to 1 with the
ldraw part filenames, import and export should be smooth. If you can
create parts in Autocad without copying the ldraw primitives, that's
probably OK.
> Also, when you are coverting the other way round (from Ldraw to AutoCad) it
> would store all repeating elements as AutoCad blocks, in a more efficient
> way than in a volume model generation tree. A volume model generation tree
> has a limited depth (I still have to look up how much branches).
From the only examples I've seen of this: DAT2DXF.EXE and the accompanying
Brick Generator program, using faces seems to generate way too much data
to really be useful. The only reason I can think of to import data into
AutoCAD would be if you're more comfortable *building* models in AutoCAD.
Maybe I'm missing something though...
On the other hand, I can see reasons for using AutoCAD to create part
files using faces, or using it to build model files with simple blocks
which can be exported to DAT files and then on to POV renderings.
That's two vastly different ways to use AutoCAD and probably requires
two different approaches to modeling the bricks. Once again, I could
be totally wrong here.
Don
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Message has 1 Reply:
 | | Re: DAT to DXF again
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| (...) Yes, just like Ldraw Prinitives, Autocad Blocks are nestable. And to my knowledge without limits. (...) I can make a simple AutoCad model representing an instance of the box5.dat primitive to see what you can make of that (plus some (...) (22 years ago, 8-Oct-02, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: DAT to DXF again
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| (...) I would like to discuss this because I'm not sure that would be the best path to follow. Translating (AutoCad) volume models into (Ldraw) face models could proove to be difficult. Maybe you're better off to build the Autocad model with faces (...) (22 years ago, 7-Oct-02, to lugnet.cad.dev)
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