DXF文件格式详解：AutoCAD的交互与应用

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AutoCAD can be used by itself as a complete drawing editor. In some 
applications, however, other programs must examine drawings created 
by AutoCAD or generate drawings to be viewed, modified, or plotted 
with AutoCAD.

For example, if you've made an architectural drawing with AutoCAD, 
using inserted parts to represent windows, doors, and so on, you can 
process the drawing file and produce a bill of materials of all 
items used in the drawing, or even make energy-use calculations 
based on the area and the number and type of windows used. Another 
possible application is to use AutoCAD to describe structures and 
then send the descriptions to a more powerful computer for finite-
element structural analysis. You can compute stresses and 
displacements and send back information to display the deformed 
structure as an AutoCAD drawing.

Since the AutoCAD drawing database (.dwg file) is written in a 
compact format that changes significantly as new features are added 
to AutoCAD, we do not document its format and do not recommend that 
you attempt to write programs to read it directly. To assist in 

interchanging drawings between AutoCAD and other programs, a Drawing 
Interchange file format (DXF) has been defined. All implementations 
of AutoCAD accept this format and are able to convert it to and from 
their internal drawing file representation.

AutoCAD also supports the Initial Graphics Exchange Specification 
(IGES) file format. The information comprising an AutoCAD drawing 
can be written out in IGES format, and IGES files can be read and 
converted to the AutoCAD internal format.


ASCII Drawing Interchange (DXF) Files
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This section describes the AutoCAD DXF (drawing interchange file) 
format and the commands provided to read and write these files. DXF 
files are standard ASCII text files. They can easily be translated 
to the formats of other CAD systems or submitted to other programs 
for specialized analysis. AutoCAD can also produce or read a binary 
form of the full DXF file. This feature is described in detail later 
in this chapter.


DXFOUT Command - Writing a DXF File
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You can generate a drawing interchange file from an existing drawing 
by means of the DXFOUT command:

   Command: dxfout