DXF Export -- Arc Direction

When I export a 3dm file to dxf, I see results I don’t understand.

j-outline.3dm (47.9 KB)
j-outline.dxf (11.1 KB)

File j-outline.3dm is a planar outline–a curve containing 1 closed polycurve of 31 arcs. The arcs have a consistent direction (clockwise per command “Analyze Direction”.

File j-outline.dxf is an “Export (R12 Lines and Arcs)” of j-outline.3dm. When I open it with Rhino I see 31 curves, each an arc. So far so good. But the directions of the arcs vary (again per command “Analyze Direction”).

I don’t see a pattern to the direction changes. They confuse my cheap-o CAM program (LazyCAM).

Any pointers (besides “get a better CAM program”)?


MacBook Pro, Retina, Mid 2012
OS X 10.8.5 (12F45)
5.0 Wenatchee 2014-05-20 (514)

Hi bch- so far I do not see why this is happening, I’ll check with the developer.

@lowell, any ideas?



I suspect it is because AutoCAD arcs are always counter-clockwise. Rhino’s can go either way.
Windows Rhino has a control for arc direction in the DWG/DXF names scheme export.
I don’t know if that U/I has been implemented in Mac Rhino yet.

Thanks for looking at this. I think you’re right about the UI; I don’t see an option in the MacOS export scheme dialog for direction. I guess I’ll just be patient. Out of curiosity, what is the option called in the Windows dialog?

It looks like this in the Windows Rhino U/I: