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1991-12-30
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DXF3DS
Autodesk 3D Studio DXF Conversion Utility
Copyright 1991 Dan Silva
For distribution among 3D Studio users. NOT FOR SALE.
Produced Exclusively for Autodesk, Inc.
by
Yost Group, Inc.
12-31-91
Converts DXF files to 3DS, SHP, or LFT files, and converts FLM
files to 3DS files. This program addresses many of the
limitations of the built-in DXF translation that was included
with 3D Studio release 1.0. The major features of DXF3DS include
the conversion of AutoCAD Blocks and Extruded lines, automatic
welding/unifying/smoothing of the resulting objects, better
handling of face normals, and the ability to convert AutoCAD 3D
polylines to Lofter path (.LFT) files.
Usage:
dxf3ds froon.dxf ..Switches..
or
dxf3ds baz.flm ..Switches..
Switches
/T "to" file type: ( default to .3DS )
/TS output .SHP file containing Shape.
/TL output .LFT file containing Path.
/T3 output .3DS file containing Objects.
Note: The resulting file will get written to
the same directory as the source DXF
file. After conversion, you will want
to put this file in the appropriate 3D
Studio directory: MESHES, SHAPES, or
LOFTS. CAUTION -- this utility will
overwrite an existing file with the same
name.
The following switches only have meaning when creating
a .3DS file:
/O object definition: ( default to "by layer" )
Note: This only works with .dxf files...
It's invalid for .flm files (filmrolls
only convert by color).
/OE by entity
/OC by color
/OL by layer
/Wnnn auto-weld Automatically welds coincident
vertices.
nnn = optional weld-threshold
in multiples of .00001 units.
Defaults to 1.
Note: Welding (and subsequent
Unifying) can only take place
within a given 3DS "Object"
group. Welding can not happen
between objects. Remember
this when you create your
objects in AutoCAD, and
subsequently when you convert
the .dxf files into .3ds files
(by layer, color, or entity),
if you want them to be welded
and unified.
/U auto-unify Note: Only welded objects may
have their surface normals
unified. And only 3D entities
can be unified (ie, a 2D plane
floating in space cannot be
unified). This is important
to note when you convert .dxf
files into .3ds files and make
the decision to bring them in
either by layer, by color, or
by entity. Plus, although the
current unification code is
better than the 3DS 1.0 code,
it still requires you to
follow the golden rule: the
object's topology must have
integrity. This means that
every edge must be shared by
two faces, except for edges at
the object's perimeter.
/Snn auto-smooth Automatically sets smoothing
groups for the objects based
on the angle between non-
coplanar edges.
nn = optional edge angle
threshold.
Defaults to 30 degrees.
Note: Only welded objects can
have smoothing groups
assigned.
/Ann arc-smoothness Arc step size for polyline
conversion.
nn = step angle in degrees.
Defaults to 10 degrees.
(Note that this only needs to
be lowered if you want
smoother arcs as they're
converted from Acad polylines
into 3DS objects. It'll most
likely never need to be raised
above 10-degrees, since that
will make arcs coarser.)
--------
Examples:
To convert from FROON.DXF to FROON.3DS, defining objects by
Entity, welding with a threshold of .001, auto-unifying surface
normals, smoothing with an angle threshold of 40 degrees, and
arc-smoothing with an angle threshold of 3 degrees:
dxf3ds froon.dxf /OE /W100 /U /S40 /A3
To convert from DWEEB.FLM to DWEEB.3DS, welding with a
default threshold of .00001, auto-unifying surface normals,
smoothing with a default angle threshold of 30 degrees, and arc-
smoothing with the default threshold of 10 degrees (arc smoothing
is done automatically, so no switch is needed to accept the
default):
dxf3ds dweeb.flm /w /u /s
To convert from DWEEB.DXF to DWEEB.SHP: (note: will only
convert 2D polylines)
dxf3ds dweeb.dxf /ts
To convert from DWEEB.DXF to DWEEB.LFT: (note: will only
convert the last found 3D polyline)
dxf3ds dweeb.dxf /tl
A sample batch file "DXF3DSL.BAT" is included to show you
how you might automate your conversion with preferred switches.
To convert DWEEB.DXF to DWEEB.3DS defining objects by layer,
with an auto-smoothing angle threshold of 35 degrees, autoweld
on, and auto-unification of surface normals, type:
dxf3dsl dweeb
dxf3dsl.bat contains:
dxf3ds %1.dxf /Ol /W /U /S35
You may want to modify this to customize it for your
particular needs.
_____________
Installation:
Two versions of this utility are included:
DXF3DS.EXE - INTEL version
DXF3DSW.EXE - WEITEK version for PC's that are
configured with only a WEITEK math
coprocessor.
______________
Helpful Notes:
1) Some of the techniques as outlined in Appendix B of the 3D
Studio reference manual for working with DXF files no longer
apply.
- You no longer have to explode AutoCAD AME meshes prior
to making the DXF file.
- Welding and smoothing is now done automatically.
- You no longer have to use Filmrolls if your AutoCAD
drawing contains Blocks and Extruded lines.
2) DXF files produced by GENERIC CADD's 3DD are accepted by
this utility.
3) Recommended procedure for Using 3D Studio to create
walkthroughs of architectural models produced in AutoCAD.
- While in AutoCAD, create a 3D Polyline that defines a
camera path through your building. If you have more
than one 3D Polyline in your model, turn off or freeze
the layers that contain the other polylines.
- Create a DXF file.
- Convert the DXF file to a 3DS file using DXF3DS.
- Convert the DXF file to a .LFT file using DXF3DS /TL.
- In the 3D Editor, assign materials and add lights.
- In the Keyframer, use Get Path and select the .LFT file
that contains the converted 3D Polyline. You may want
to assign a dummy to this path and link your camera and
target to the dummy. (Note, if you want the camera to
track the target, you'll have to slide the camera keys
back in time so the camera is following the dummy.)
4) After converting a DXF file to a 3DS file, you may want to
break down the resulting 3D Studio objects into smaller
objects. A technique for doing this is:
- Use Select Face to select faces that you want to
convert into separate objects.
- Use Create/Face/Detach with the "SELECTED" button on.
This will prompt you for the name of the selected
objects.
5) The following AutoCAD Entities in DXF files get converted to
3D Studio Objects:
- 3D faces and polygon meshes
- Circles, solids, traces, doughnuts, polylines with
width, closed arcs, closed 2D polylines, and extruded
polylines
- Any extruded entities
- Polyface meshes from AutoCAD Release 11
- AutoCAD blocks containing any of these entities
- Entities on frozen or turned-off layers are ignored
6) AutoCAD Advanced Modeling Extension (AME) note: Remember
while still in AutoCAD to use SOLMESH on AME models prior to
exporting a DXF file for conversion to 3D Studio.
7) As noted above, the successful unification of face normals
depends on the welding of coincident vertices. Sometimes,
depending upon the precision of the model as it was created
in AutoCAD, the vertices may not be "coincident enough" for
proper face normal unification. In this case, you may have
to increase the weld-threshold to account for any floating-
point round-off errors that occur when the converter looks
for coincident vertices. This is especially true when
converting models produced in AutoCAD release 11 with the
AME (Advanced Modeling Extension) version 1.0. This is
because AME 1.0, like 3D Studio, uses single precision
floating point calculations.
Example: A DXF file was produced from an AutoCAD AME model
of a skateboard. This DXF file was converted to a
3DS file. The first time the default weld-
threshold was used, which resulted in some
incomplete surface-normal unification. This DXF
file was converted again, but this time /W100 was
used -- which resulted in correct surface-normal
unification.
8) Converting DXF files using the "By Layer" Object Definition
method can result in objects consisting of many elements.
In certain cases, some of these elements may have all of
their face normals flipped the wrong way. This is
detectable in 3D Studio by selecting Backface in the
Display/Geometry command menu. Use Surface/Normals/Element
Flip to correct this. Note: If you would rather not pay
attention to face normals when using 3D Studio to Render
AutoCAD-produced models, use 2-Sided Materials.
9) If you are loading a large scene containing thousands of
entities (such as 3D faces) and have chosen to bring objects
in "by entity," it can take a tremendous amount of time to
create the file. It will also create huge numbers of
objects which you'll have to wade through in 3D Studio. We
recommend that you organize your DXF file in AutoCAD so that
these kinds of entities are grouped by layer, and that you
make the conversion into 3D Studio "by layer."
10) If you have created a DXF file that doesn't successfully
load into 3D Studio after being converted by this utility,
please send us the file on a floppy disk with a document
describing how you made the file, (both the technique and
with what version of AutoCAD or other program), and what
exactly the nature of the problem is. Send it to:
Autodesk 3D Studio DXF3DS tech support
Autodesk, Inc.
2320 Marinship Way
Sausalito, CA 94965
[end]