Expert: Bill DeShawn - 5/12/2003

Question
I have an application that can import 2D shapes via DXF and the software recommends using AutoCAD to create them.  In AutoCAD I need to create a single 2D shape that looks like a circle with a polygon cut out of the center.  I've created two shapes, converted them to regions, used subtract to remove the inner polygon region from the larger circle region, but when I export this final product as DXF and import into the other application it says there are no objects in the file that it understands.  I am assuming I need to convert the resulting boolean region back to a polyline, spline, faces, or something else before exporting to DXF.  I've tried explode but I only get a collection of line segments instead of one large positive object with negative space in the center.  Could you suggest a procedure or format I could convert to that would be basic (not 3D or complex) yet retain the pos/neg/inner/outer regions in a single object?  Thanks!

Answer
First off, DXF files come in many flavors (versions).  You need to coordinate the version of program with which you are working with the version of DXF you need.  That is usually the most difficult step in the process.  Will it work without changing the objects to regions?  Also, subtract is a command used for 3D solids.  You say you want 2D shapes.  If you really want a shape object that is also another animal, but I think you really want an object or group of objects of a particular geometry.  Lines and polylines to a great job and are easily translated to DXF.  Perhaps you should define a block.  A block is a single object that is explodable and remains as one object if resides in a DXF file.

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