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From: olasov@heathcliff (Benjamin Olasov)
Newsgroups: comp.graphics
Subject: True 3D IGES interface output from AutoCAD
Keywords: DXF IGES Copious Data Entities
Message-ID: <6197@columbia.edu>
Date: 5 Mar 89 21:34:19 GMT
References: <1939UD140469@NDSUVM1>
Sender: news@columbia.edu
Reply-To: olasov@heathcliff.UUCP (Benjamin Olasov)
Organization: Columbia University
Lines: 21

AutoCAD's IGES preprocessor typically creates a form 1 (coordinate pair) format
for entity type 106 (a copious data entity [a 3DFACE in AutoCad nomenclature]).
Entity 106 is handled by the tranformation matrix (entity 114) if the
coordinate pair format is used.

It doesn't seem to be possible to coerce AutoCad to produce a form 2
(coordinate triplet) format instead in its IGES output file (IGESOUT).
This makes reading the IGES file produced by AutoCad's IGES preprocessor
by a post-processor like Neo-Visuals or other 3D and animation software
virtually impossible.  It also makes it very difficult to produce a LISP
based object file that could be read by the S-Geometry package on a Symbolics
LISP machine.

Has anyone come up with, or discovered, a package that can produce an
IGES file specifying copious data entities as coordinate triplets (i.e.
a 2 flag on the 106 entity)?  I'd also be interested to hear whether anyone
has already written some code for translating an AutoCad database of any format
into a (LISP Machine) S-Geometry readable object file.

Cheers,
Ben