SDXF – Python Library for DXF

Stani’s DXF library for python is an excellent tool for writing lines, circles, and polygons in DXF format. DXF (Document Exchange Format) is an ASCII file format published by AutoCad which can be read by a variety of programs, including Blender, Maya, CorelDraw, and a host of others.

I’ll attempt to document the library here as I figure it out, and also release updates to it as I slowly add more element types. I’m learning python and the DXF format as I go along so I can’t guarantee that any of this is correct.

Download SDXF 1.1.1

Changes in 1.1.1

• Added support for LWPOLYLINE, so you can now make a continuous polyline instead of several separate lines

Example Code

This will draw a line from (0,0) to (1,1) and “Hello World” at (3,0)

import sdxf

d=sdxf.Drawing()

#set the color of the text layer to green
d.layers.append(sdxf.Layer(name="textlayer",color=3))

#add drawing elements
d.append(sdxf.Text('Hello World!',point=(3,0),layer="textlayer"))
d.append(sdxf.Line(points=[(0,0),(1,1)], layer="drawinglayer"))

d.saveas('hello_world.dxf')

Overview

Entities

An Entity is an individual drawing object, like a line or circle. These are appended to the Drawing and rendered in the order they’re added.

Layers

Layers are used to organize entities. Layers can be assigned colors to make drawings easier to read. An entity can be assigned to a new layer on the fly, without explicitly defining the layer first.

Layer(name="mynewlayer",color=8)

Blocks

Blocks are reusable symbols. A block is defined once and can then be appended to the drawing using the Insert entity. A block can be inserted multiple times into a drawing, at different points.

#define the block, a Solid and an Arc
b=Block('test')
b.append(Solid(points=[(0,0,0),(1,0,0),(1,1,0),(0,1,0)],color=1))
b.append(Arc(center=(1,0,0),color=2))

#create a new drawing
d=Drawing()

#add the block to the Blocks table, so it can be referenced later
d.blocks.append(b)

#add entities to the drawing, including the block using the Insert entity
d.append(Circle(center=(1,1,0),color=3))
d.append(Face(points=[(0,0,0),(1,0,0),(1,1,0),(0,1,0)],color=4))
d.append(Insert('test',point=(3,3,3),cols=5,colspacing=2))
d.append(Line(points=[(0,0,0),(1,1,1)]))

Supported Entities

These entities are currently in the library. In addition to passing the arguments for the individual entity type, you can pass common arguments (group codes) which are available for all entities.

Common Group Codes

• color – the color of the entity. Represented by a number. See the Color List below.
• extrusion – ?
• layer – which layer to place the element on. You do not need to explicitly declare a layer before assigning entities to it
• lineType – ?
• lineTypeScale – ?
• thickness – thickness of the entity lines
• parent – ?

Arc

Draws an arc (part of a circle).

• center (x, y, z) – The center of the circle from which the arc is to be taken. Z is optional.
• radius – The radius from the center to the arc
• startAngle – The angle, in degrees, for the start of the arc.
• endAngle – The angle, in degrees, for the end of the arc

Arc(center=(3,0),radius=2,startAngle=0,endAngle=90)

Circle

Draws a circle.

• center (x,y,z) – the center of the circle. Z is optional.
• radius – the radius of the circle

Arc(center=(3,0),radius=2)

Face

Creates a 3d face. A 3d face takes 4 points, which may or may not all be on the same plane.

Insert

Blocks are added to a file using the Insert entity. The block must be added to the Blocks table before it can be used.

• name – Block name (defined when the block was added to the Blocks table)
• point – Insertion point (x,y,z) to add the block
• xscale – x scale factor; optional, defaults to 1
• yscale – y scale factor; optional, defaults to 1
• zscale – z scale factor; optional, defaults to 1
• cols – column count; optional, defaults to 1
• colspacing – column spacing; optional, defaults to 0
• rows – row count; optional, defaults to 1
• rowspacing – row spacing; optional, defaults to 0
• rotation – rotation angle; optional, defaults to 0

Insert('test',point=(3,3,3),cols=5,colspacing=2)

Line

Makes a line! Takes a list containing two points. Points can be (x,y) or (x,y,z)

Line(points=[(0,0),(1,1)])

LwPolyLine

Makes a line with vertexes. Takes a list of points.

linePoints = [(0,0),(1,1),(1,0)]
LwPolyLine(points=linePoints,flag=1)

Polyline

In the current implementation, actually just makes a bunch of Lines rather than a polyline.

Point

A point in space. Takes a point (duh).

Solid

From what I can tell, this creates a 3D solid by taking either 3 or 4 points and then extruding the face in various directions.

Text

Renders a string as text at the given point.

Text('Hello World!',point=(3,0))

Mtext

I think this is like Text but supports line breaks. In this version of SDXF it just creates multiple Text entities.

Extras

These are not actual DXF entities, but are classes that make building other shapes easier.

Rectangle

Creates a rectangle using 4 lines. Could probably be modified to use LwPolyLine instead.

• point – lower left (?) corner point
• width – rectangle width
• height – rectangle height
• solid – ?
• line – ?

Line List

Creates a bunch of lines from a set of points. Currently used instead of PolyLine.

• points – list of verticies
• closed – whether to close the shape; defaults to 0

Color List

The colors may vary depending on the rendering software used.
1 – Red
2 – Yellow
3 – Green
4 – Cyan
5 – Blue
6 – Magenta
7 – White
8 – Black