Draft DXF

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Description

Draft DXF is a software module used by the Std Open.svg Std Open, Std Import.svg Std Import and Std Export.svg Std Export commands to handle the DXF file format.

Screenshot qcad.jpg

Qcad drawing exported to DXF, which is subsequently opened in FreeCAD

Importing

Two importers are available, which one is used can be specified under Edit → Preferences... → Import-Export → DXF. One is built-in, C++-based and fast, the other is legacy, coded in Python, slower, and requires the installation of an add-on, but can handle some entities better and can create more refined FreeCAD objects. Both support all DXF versions starting from R12.

3D solids inside a DXF file are stored under a binary ACIS/SAT blob, which at the moment cannot be read by FreeCAD.

C++ importer

This importer can import the following DXF objects:

  • lines
  • polylines (and lwpolylines)
  • arcs
  • circles
  • ellipses
  • splines
  • points
  • texts and mtexts
  • dimensions
  • leaders
  • blocks (only geometry, texts, dimensions and attributes inside blocks are skipped)
  • layers
  • paper space objects

Legacy importer

This importer can import the following DXF objects:

  • lines
  • polylines (and lwpolylines)
  • arcs
  • circles
  • ellipses
  • splines
  • 3D faces
  • texts and mtexts
  • leaders
  • layers

Exporting

There are also two exporters. The legacy exporter exports to the R12 DXF format, the C++ exporter to the R14 DXF format. Both formats can be handled by many applications.

C++ exporter

Some of the features and limitations of this exporter are:

  • All FreeCAD 2D geometry is exported, except Draft CubicBezCurves, Draft BezCurves and Draft Points.
  • Straight edges from faces of 3D objects are exported, but curved edges only if they are on a plane parallel to the XY plane of the global coordinate system. Note that a DXF created from 3D objects will contain duplicate lines.
  • Texts and dimensions are not exported.
  • Colors are ignored.
  • Layers are mapped from object names.

Legacy exporter

Some of the features and limitations of this exporter are:

  • All FreeCAD 2D geometry is exported, except Draft Points. But ellipses, B-splines and Bézier curves are not exported properly.
  • 3D objects are exported as flattened 2D views.
  • Compound objects are exported as blocks.
  • Texts and dimensions are exported.
  • The colors in the DXF are based on the line color of objects. Black is mapped to "ByBlock", other colors are mapped using AutoCAD Color Index (ACI) colors.
  • Layers are mapped from layer and group names. When groups are nested, the deepest group gives the layer name.

Installing

For licensing reasons, the required DXF import/export libraries needed by the legacy version of the importer are not part of the FreeCAD source code. For more information see: FreeCAD and DXF Import.

Preferences

See Import Export Preferences.

DWG

Because the DWG format is a proprietary, closed and undocumented format it is hard for open-source projects like FreeCAD to support it. That is why FreeCAD relies on external converters to read and write DWG files. To import a DWG file a converter is used to create a DXF first, which can then be processed by the FreeCAD DXF importer. When exporting to DWG the opposite conversion happens: the DXF created by the FreeCAD DXF exporter is turned into a DWG.

Note that the DXF format allows a 1:1 conversion of the DWG format. All applications that can read and write DWG files can do the same with DXF files, with no data loss. So asking for DXF files instead of DWG files, and supplying DXF files in turn, should not cause any problems.

There is built-in support for the following DWG converters:

See Import Export Preferences and FreeCAD and DWG Import for more information.

Scripting

See also: Autogenerated API documentation and FreeCAD Scripting Basics.

To export objects to DXF use the export method of the importDXF module.

importDXF.export(objectslist, filename, nospline=False, lwPoly=False)
  • For the Windows OS: use a / (forward slash) as the path separator in filename.

Example:

import FreeCAD as App
import Draft
import importDXF

doc = App.newDocument()

polygon1 = Draft.make_polygon(3, radius=500)
polygon2 = Draft.make_polygon(5, radius=1500)

doc.recompute()

objects = [polygon1, polygon2]
importDXF.export(objects, "/home/user/Pictures/myfile.dxf")