Draft DXF

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Revision as of 10:56, 1 September 2021 by Roy 043 (talk | contribs) (Legacy exporter...)
This documentation is a work in progress. Please don't mark it as translatable since it will change in the next hours and days.

Description

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

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 objects inside a DXF file are stored under a binary ACIS/SAT blob, which at the moment cannot be read by FreeCAD. Simpler entities like 3DFACEs, though, are supported.

The following DXF objects can be imported:

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

Exporting

There are also two exporters. The legacy exporter exports in the R12 DXF format, the C++ exporter in 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, BSplines 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

For more information see: Import Export Preferences.

Scripting

See also: Draft API and FreeCAD Scripting Basics.

You can export elements to DXF by using the following function:

importDXF.export(objectslist, filename, nospline=False, lwPoly=False)

Example:

import Draft, importDXF

Polygon1 = Draft.makePolygon(3, radius=500)
Polygon2 = Draft.makePolygon(5, radius=1500)

objects = [Polygon1, Polygon2]

importDXF.export(objects, "/home/user/Pictures/myfile.dxf")