       Re: DXF & imp3D

• To: mathgroup at yoda.physics.unc.edu
• Subject: Re: DXF & imp3D
• From: Roberto Sierra <73557.2101 at compuserve.com>
• Date: 24 Jun 93 03:31:22 EDT

```Regarding Mitja Lakner's problems with WriteDXF:

>   I have problems with WriteDXF (only with ImplicitPlot3D).
>
>   g = ImplicitPlot3D[E^z Cos[x] == Cos[y],
>                {x,-6,6}, {y,-6,6}, {z,-6,6},
>                PlotPoints->{16,16,12},
>                Passes->4]
>   g = Graphics3D[g];
>   WriteDXF["g.dxf",g,PolygonsOnly->True]
>
>   I get file, but there are (at least) mistakes:
>   empty polygons and unevaluated fractions.

You can fix DXF.m by making the following changes:

(1) EMPTY POLYGONS
In the definition of WriteDXF, change

parts = Cases[pic,(Polygon[_?(Length[#] <= 4 &)] |
_Line | _Point),

to

parts = Cases[pic,(Polygon[_?(0 < Length[#] <= 4 &)] |
_Line | _Point),

(2) UNEVALUATED FRACTIONS
In the definition of writegroup, change

WriteString[stream,rightjustifynum[code],cr,
ToString[CForm[it]],cr]

to

WriteString[stream,rightjustifynum[code],cr,
ToString[CForm[N[it]]],cr]

This seems to fix the specific problems you encountered, though
I don't have AutoCAD to fully test the DXF output.  Hope this
helps.

P.S.
In your original message, the line
g = Graphics3D[g];
will cause problems, since the output from ImplicitPlot3D is
already a Graphics3D object.  There is no need to coerce it.

\\|//
- -
o o
J   roberto sierra
O   tempered microdesigns
\_/  73557.2101 at compuserve.com

```

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