Automate AutoCAD with Python & pyautocad

Overview

• pyautocad is
  • open source so you can use it for free
  • it uses ActiveX Automation to control AutoCAD, so it’s basically a wrapper for AutoCAD VBA API
  • it’s not in active development, last commit was in 2016
  • Bad Documentation
• Requirements
  • pyautocad required Full version of AutoCAD installed on your system
  • AutoCAD LT won’t work with pyautocad

Setup

• use Pip install pyautocad to install xlwings package

Connect with AutoCAD

• use from pyautocad import Autocad to import Autocad class
• This sample code just print “Hello, World” to your AutoCAD prompt
• Create New AutoCAD file

cadApp = Autocad(create_if_not_exists=True)
cadApp.prompt("Hello,World\n")

• Use Existing AutoCAD file

cadApp = Autocad()
cadApp.prompt("Hello,World\n")

Create New Entity

• Since pyautocad uses AutoCAD VBA behind the scenes, you can create any AutoCAD entity using AutoCAD VBA API
• Only Difference is how we access our Document and modelspace
• I’ve added sample code to create new circle in modelspace, you can follow this same process to create another object

Circle

• This code will create new circle in your active autocad document
• as you can see it’s similar to AutoCAD VBA
• AutoCAD have lot of objects so i am not going to write sample code for all object only main ones
• you can visit Getting Started with AutoCAD VBA to get access to VBA API
• Just use same method to generate autocad objects

from pyautocad import Autocad, APoint

cadApp = Autocad()
cadDoc = cadApp.ActiveDocument
cadModel = cadDoc.ModelSpace

# APoint is custom class for AutoCAD Point
# It's part of pyautocad library
centerPoint = APoint(0, 0)
radius = 10.0
cadCircle = cadModel.AddCircle(centerPoint, radius)

Line

startPoint = APoint(10, 20)
endPoint = APoint(20, 30)
cadLine = cadModel.AddLine(startPoint, endPoint)

Polyline

• since polyline require multiple point, we can’t use APoint class here
• we have to use array library to pass multiple points
• import array to use array library

# Create 2D point array
points_2d = [0, 0, 10, 0, 10, 10, 0, 10]
points_double = array.array("d", points_2d)
cadModel.AddLightWeightPolyline(points_double)

• if you want to add one point at a time

# Create 2D point array
points_2d = []

points_2d.append(0)
points_2d.append(0)

points_2d.append(10)
points_2d.append(0)

points_2d.append(10)
points_2d.append(10)

points_2d.append(0)
points_2d.append(10)

points_double = array.array("d", points_2d)
cadModel.AddLightWeightPolyline(points_double)

Text

textString = "Hello World"
insertionPoint = APoint(0, 0)
textHeight = 2
cadText = cadModel.AddText(textString, insertionPoint, textHeight)

Read Data from existing drawing

loop through specific objects in active drawing

• Loop through all text objects
• once you have access to the object, you can access its properties similar to AutoCAD VBA

point = APoint(0, 0)
for text in cadApp.iter_objects('Text'):
    print('text: %s at: %s' % (text.TextString, text.InsertionPoint))
    text.InsertionPoint = APoint(text.InsertionPoint) + point

for circle in cadApp.iter_objects('Circle'):
    print(circle.Center)

for line in cadApp.iter_objects('Line'):
    print(line.StartPoint, line.EndPoint)

Conclusion

• pyautocad is good option if you want to automate AutoCAD using python
• If you’re newbie then i would advise you to skip this package and use something else due to lack of documentation

If you have any questions or want to discuss something : Join our comment section