The main data structure used in the Part module is the BRep data type from OpenCascade. Almost all contents and object types of the Part module are available by Python scripting. This includes geometric primitives, such as Line and Circle (or Arc), and the whole range of TopoShapes, like Vertexes, Edges, Wires, Faces, Solids and Compounds. For each of those objects, several creation methods exist, and for some of them, especially the TopoShapes, advanced operations like boolean union/difference/intersection are also available. Explore the contents of the Part module, as described in the FreeCAD Scripting Basics page, to know more.
The most basic object that can be created is a Part Feature, which has a simple DataPlacement property, and basic properties to define its color and appearance.
import parttests.part_test_objects as pto pto.create_test_file("example_file")
This script is located in the installation directory of the program, and can be examined to see how the basic primitives are built.
To create a line element switch to the Python console and type in:
import Part,PartGui doc=App.newDocument() l=Part.LineSegment() l.StartPoint=(0.0,0.0,0.0) l.EndPoint=(1.0,1.0,1.0) doc.addObject("Part::Feature","Line").Shape=l.toShape() doc.recompute()
Let's go through the above python example step by step:
import Part,PartGui doc=App.newDocument()
loads the Part module and creates a new document
l=Part.LineSegment() l.StartPoint=(0.0,0.0,0.0) l.EndPoint=(1.0,1.0,1.0)
Line is actually a line segment, hence the start and endpoint.
This adds a Part object type to the document and assigns the shape representation of the line segment to the 'Shape' property of the added object. It is important to understand here that we used a geometric primitive (the Part.LineSegment) to create a TopoShape out of it (the toShape() method). Only Shapes can be added to the document. In FreeCAD, geometry primitives are used as "building structures" for Shapes.
Updates the document. This also prepares the visual representation of the new part object.
Note that a Line Segment can be created by specifying its start and endpoint directly in the constructor, for example Part.LineSegment(point1,point2), or we can create a default line and set its properties afterwards, as we did here.
A Line can be created also using:
import FreeCAD import Part DOC = FreeCAD.newDocument() def mycreateLine(pt1, pt2, objName): obj = DOC.addObject("Part::Line", objName) obj.X1 = pt1 obj.Y1 = pt1 obj.Z1 = pt1 obj.X2 = pt2 obj.Y2 = pt2 obj.Z2 = pt2 DOC.recompute() return obj line = mycreateLine((0,0,0), (0,10,0), "LineName")
A circle can be created in a similar way:
import Part doc = App.activeDocument() c = Part.Circle() c.Radius=10.0 f = doc.addObject("Part::Feature", "Circle") f.Shape = c.toShape() doc.recompute()
import FreeCAD import Part DOC = FreeCAD.newDocument() def mycreateCircle(rad, objName): obj = DOC.addObject("Part::Circle", objName) obj.Radius = rad DOC.recompute() return obj circle = mycreateCircle(5.0, "CircleName")
or create a circle defined by it's center, axis and radius using:
import Part doc = App.activeDocument() center = App.Vector(1,2,3) axis = App.Vector(1,1,1) radius = 10 c=Part.Circle(center,axis,radius) f = doc.addObject("Part::Feature", "Circle") f.Shape = c.toShape() doc.recompute()
or create a circle defined by three points using:
import Part doc = App.activeDocument() p1 = App.Vector(10,0,0) p2 = App.Vector(0,10,0) p3 = App.Vector(0,0,10) c = Part.Circle(p1,p2,p3) f = doc.addObject("Part::Feature", "Circle") f.Shape = c.toShape() doc.recompute()
Note again, we used the circle (geometry primitive) to construct a shape out of it. We can of course still access our construction geometry afterwards, by doing:
s = f.Shape e = s.Edges c = e.Curve
Here we take the shape of our object f, then we take its list of edges. In this case there will be only one because we made the whole shape out of a single circle, so we take only the first item of the Edges list, and we takes its curve. Every Edge has a Curve, which is the geometry primitive it is based on.
Head to the Topological data scripting page if you would like to know more.