Hi Colin, I guess that option in Rhino makes wiggly curve objects to be exported as a bunch of separate line entities.

Currently MoI does not have any equivalent option for that exact option, the current options that MoI has for writing out arbitrary curves (curves that are not in the shape of a simple line, arc, or circle) are:

Write curves as: Splines = write the curve as a SPLINE entity in the DXF file. This is an exact conversion (meaning it does not involve approximating the curve with other shapes like lines).

Write curves as: Cubic splines = write the curve as a SPLINE entity but refit any curves that use weights or high degree so that only the most basic kind of spline curve is used. This can help with programs that can read in SPLINE entities but don't support them 100% like they don't read in weight values.

Write curves as: Polylines = break the curve into a series of line segments and write them out as a POLYLINE entity in the DXF file with the vertices of the polyline forming the lines.


From what I can see, most likely that Rhino option will break curves into a series of line segments and then write out a separate LINE entity in the DXF file for each one. I wouldn't think you would want that since it basically kind of loses the built in sort of grouping of lines that a POLYLINE has.

The closest thing in MoI currently would be "Write curves as: Polylines" - it may be worth sending them a test file written with that just to see if they actually cannot handle polylines, that would be kind of weird if everything had to be only individual line entities and not polylines. Please let me know if that is indeed the case and I can add in a new option for that into MoI's export.

One thing you could do to get individual line entities out from MoI would be to export with "Write curves as: Polylines", then read that DXF file back into MoI and run Edit > Separate on it to break the polylines down into a bunch of individual line objects, then when you exported the result of that back to DXF, each of those individual lines will get written as a LINE entity.


But also an additional factor - I took another look right now at that particular Rhino export mode and it looks like it will break down arcs and circles down into lines as well, rather than exporting ARC or CIRCLE entities for them. By default MoI will write lines, arcs, and circles as a LINE, CIRCLE, or ARC entity inside the DXF file and not break them down into polylines. That could be a problem if your receiving software does not support CIRCLE or ARC entities, although those are really basic DXF entities that have been around forever so it's again pretty weird for them to not be supported at all by a program that reads in DXF files.

You can turn off exporting of these special entities from MoI in moi.ini, go to Options > General and push the "Edit .ini file" button and find the [DXF Export] section, then inside there is a setting for:

[DXF Export]
UseSimpleEntities=y


If you change that to UseSimpleEntities=n then lines, circles, and arcs will not be treated differently from any other curves and will get exported as either a SPLINE or a POLYLINE entity depending on the curve export setting.

- Michael